Atomic Structure

ATOMIC STRUCTURE
1. Relate the number of protons, neutrons and electrons in an atom (including
isotopes) or a monatomic ion, to the atomic number, mass number and charge.
2. State the electron arrangement of atoms and/or ions of the first 20 elements in
the Periodic Table.
3. Relate the charge on monatomic ions to the position of the element on the Periodic
Table.
4. State the electron arrangement of atoms and/or ions of the first 20 elements in
the Periodic Table.
5. Relate the charge on monatomic ions to the position of the element in the Periodic
Table
6. Draw Lewis diagrams of :
• atoms selected from the first 20 elements
• molecules including those with single bonds, e.g. H2O, CH4, H2, Cl2 & PCl3 and
those with multiple bonds

Thursday, 22 April 2010

Term Definition GLOSSARY 1
crystal
lattice
melting
boiling


atom
element
proton
electron
neutron
neutral
atomic number
mass number
group
row
valence
relative
isotope
octet rule
duet rule
valence
molecule


Term Definition GLOSSARY 1 - MATCH UP
A. geology 1. natural substances with a definite composition and structure
B. rock 2. formation of crystals from molten rock or solution
C. minerals 3. describes solids which do not have a crystalline structure
D. elements 4. solid substances showing definite geometrical shapes
5. mass of an object compared to the mass of the same volume
E. compounds
of water
F. crystals 6. substances made of identical atoms
G. solidify 7. the degree of shine on the surface of a solid
H. crystallise 8. light does not pass through
I. amorphous 9. changing from a molten to as solid state
J. lustre 10. study of the Earth’s structure and its rocks
K. relative 11. used to describe an object which will affect a nearby
density compass needle
L. magnetic 12. made out of crystals
M. crystalline 13. light passes through but not clearly
N. transparent 14. substances made of non-identical atoms bonded together
O. translucent 15. light passes through clearly
P. opaque 16. solid, non-living material that forms the earth’s crust

Lewis structure
lone pair
single bond
double bond
triple bond
anion
cation

group
period
reactivity
solubility
electric current


REVISION


BASICS


Elements THE BASICS Complete:

Elements are like the letters of the alphabet. There are 26
letters and these can be joined together in different ways to make up to 750 000
different words. Letters cannot be split into anything simpler.

• Elements are substances that contain particles called .
• An element consists of only one type of atom only.
• Atoms cannot be easily into anything .
• There are 90 different elements and these can be .
to make all the other in the world

Atoms
Part of Where Electrical
atom found Charge
Proton
+
+ Neutron
Proton Electron

Word list: substances, atoms,
simpler, split, joined, proton,
electron, empty space, negative,
positive, neutral, neutron, in the
“History of the atom” nucleus, outside the nucleus.

Element names

H Na

He Mg

Li Al

Be Si

B P

C S

N Cl

O Ar

F K

Ne Ca

An easy way to remember the first 20 elements Flashcards
(in exercises)
Harry He Likes Beer By Cupfuls Not Over Flowing
Never Natter Magic Although Science Possesses Some Clues
Arthur Kicks Cats “Element
Bingo” (in starters)

ELECTRON
ARRANGEMENTS


THE PERIODIC TABLE

Hydrogen - not a metal
but here because of its
electron arrangement

1 2 3 4 5 6 7 8

Non-metals

Less reactive
More reactive metals Inert gases
metals


ORGANISATION OF THE PERIODIC TABLE

Atomic number
Atomic numbers are the smaller of the two numbers associated with
each element. Atomic numbers increase by one from left to right of
the table

Rows
The atoms get larger in size from left to right across a row as their
mass increases

Columns
The atoms get larger in size and increase in mass from top to bottom
of a column. Elements in a column have similar properties. Columns
are often called groups.
Groups start at 1 (at the left) and finish with group 8 (at the right of
the table)


MASS NUMBERS & ATOMIC NUMBERS

An element in the periodic table is described like this:
The mass number is 19.
19 The number of protons plus neutrons =19
9 F
Fluorine The atomic number is 9.
There are 9 protons in the nucleus and 9 electrons around it

In this example:
The 19 particles in the nucleus are protons or neutrons I’m lost!
9 of these particles are protons
therefore there are 10 neutrons in the nucleus

Summary

For an atom:
• The atomic number gives the number of protons
• The atomic number is also gives the number of electrons
• The mass number is the number of protons plus neutrons
• neutron number = mass number - atomic number

An exercise done as a class:

4
He This shows how Helium appears in the periodic table
2
Helium

This means: The atomic number is ___.

so there are: 2 protons in the nucleus
and 2 electrons surrounding it

The mass number is ____.

so the number of protons plus neutrons =4
Therefore the number of neutrons must be ___ ( = __ - __)

number of
Symbol of element number of protons number of neutrons
electrons
11 B
5

16 O
8

28 Si 14
35 Cl 20
31 P 15

Individual Exercise TRY THIS!

number of
Symbol of element number of protons number of neutrons
electrons
9 Be
4

21 Ne
10

27 Al 13
39 K 20
15P 16
42 Ca
20

12 C 6
7 Li
3

23 Na
11

24 Mg 12
14 N
7

16S 16

ELECTRON ARRANGEMENTS

Electrons in the electron cloud are not arranged randomly around the nucleus.

• Those close to the nucleus have low energy
• Those far away from the nucleus have high
energy

Electrons are arranged in energy levels

For the 1st 20 elements there are 4 energy levels:

Level 1 can hold a maximum of 2 electrons
Level 2 “ “ “ “ “ 8 electrons

Example 1

20 protons in the nucleus
20
(the atomic number)
Ca => 20 electrons around the
40
nucleus
2.8.8.2

Electron arrangement: “ 2 in the 1st shell, 8 in the 2nd shell, .......

CONFIGURE THIS!

Use your knowledge of electron
arrangement to complete the
table below. The electron 1
arrangements are shown below H
1
the element names Hydrogen
1
4
2 He
Helium
2
7 9 11 12 14 16 19 20
3 Li 4 Be 5 B 6 C 7 N 8 O 9 F 10 Ne
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
2.1 2.2 2.3 2.4
23 24 27 28 31 32 37 40
11 Na 12 Mg 13 Al 14 Si P S Cl Ar
Sodium Magnesium Aluminium Silicon Phosphorus Sulphur Chlorine Argon
2.8.1
39 40
K Ca
Potassium Calcium


SHELL DIAGRAMS

Electrons fill up an atoms shell in order, first they fill up the
inner shell (first electron shell) then the next shell and so on

An exercise done as a class:
Process:

40 x 1. Use your periodic table to find the atomic
Ca x x
x x
x

x
number.
x x
Calcium x
x x 2. The atomic number will tell you how
x x
x many electrons there are
x x
x x
x Ca 3. Fill the electrons according to the rule:
Example 2 - Silicon Level 2 “ “ “ “ “ 8 electrons

14
28
Si
28 4. Start filling the levels from level 1.
2.8.4
5. When level 1 is full start filling level 2. When
Si
level 2 is full start filling level 3 and so on.

6. Stop filling the levels when you have used all
the electrons that the atom has.

Individual Exercise A DIFFERENT WAY OF SHOWING IT! Key: p = proton
n = neutron
Example: Fluorine, 9
19F has 9p, 10n, 9e e = electron
e
e For each of the following atoms draw the
electron shell diagram. Show the nucleus as
a solid circle.
n p e e
e n p p
n p n n p A second example
n p p p n
n n
e n p 1. 13
27Al x 2. 11
23Na
x
e x x x

x x x x
e
x x x
e x

3. 14
28Si 4. 15
31P 5. 16
32S

Homework (in science books):
(i) Be (ii) F (iii) Ne (iv) Ar

ATOMS
TO IONS

ATOMS TO IONS
An ion is an atom that has lost or gained electrons
“Ions are more stable than atoms. IONS HAVE AN OUTER SHELL THAT IS FULL...
Using this knowledge it is possible to work out the arrangement of electrons in
ions.”

Sodium atom --> Sodium ion
1 electron
E x x
x x x
lost
x

X
x
x x x
x
x x x

A x x x x
x
x x 1+ charge

M Na Na+

P Chlorine atom --> Chloride ion
1 electron
L
x x
x
x x x x x
x gained
x x x x x

E
x
x x
x x x x
x x x x

S x
x

x
x
x x
x

x
x
x

Cl Cl- 1- charge


IRONING OUT THE IONS
“Metal atoms lose electrons. Non-metal atoms gain electrons.
No more than 3 electrons can be lost or gained”

Copy & complete the following table showing the electron arrangements of the atoms
and their ions:

Metal atom Metal ion Non-metal atom Non-metal ion

C: 2, 4 no ion formed Cl: 2, 8, 7 Cl-: 2, 8, 8

Mg: 2, 8, 2 Mg2+: 2, 8 N: 2, 5 N3-: 2, 8

Li: 2, 1 Li+: 2 Ar: 2, 8, 8 No ion formed

Be O

Ca S

Al F

Na P

Draw small Beryllium Sulphide Aluminium
shell diagrams
for the
following ions

FORMULAE FOR SIMPLE IONS
Background
A chemical formula shows how atoms or ions are joined to make compounds. (A
compound consists of two or more different atoms that are joined chemically).
An ionic compound is formed when positive and negative ions are attracted to each
other. Some ions comprise groups of atoms that have gained or lost electrons. These
groups are the “-ides” or “-ates”.
A table of common ions is shown below:

+1 +2 +3 _,,
-1
H* Mg2* Al3+ c1- gz-
hydrogen magnesium aluminium chloride oxide

Li* Ca2* Fe3* oH- COr'-
lithium calcium iron(III) hydroxide carbonate

Na+ Fe2* No,* Soo'-
sodium iron(II) nitrate sulfate

K+ Cu2* HCO3- PO43-
potasslum copper(II) hydrogen carbonate Phosphate

Zn2*
zinc

Pb2+
lead


GETTING TO KNOW THE “-IDES” AND “-ATES”

“-ates” end in O4 and O3
An exercise done as a class: the rest are “-ides”

+ ion - ion Formula + ion - ron Formula
Znzr N3- ZneNz Ca2* NOs- Ca(NOs)z

Pb2* Br PbBrz Fe3* SO+2- Fe2(S04)3

I Ag* s2- Li* COs2- LizCOs

) Fe3* cl- 6 Ag* PO+3-

3 Na* 02- 7 NH+* SO+2-

K+ t- KI 8 Pbz* COs2-

Cu2* SO+2- CuSOa 9 Al3* oH-
4 Mgz+ COs2- 10 Cu2* s2-

5 Zn2* 02- 11 (+ HCOg-

On the table (above):
1. Circle the “-ates” using a red pen
2. Circle the “-ides” using a blue pen
3. and name them Exercises: “-ide or -ate”

ION FORMATION AND THE PERIODIC TABLE

1 2 Groups of the periodic table 3 4 5 6 7 8

1+ 2+ Charge on ions formed by atoms in each group 3+ 3- 2- 1-

Do not form ions


INTRODUCTION


HISTORY of the atom

See “Nigel’s” ppt on the shared drive


MATTER Nature & State


PROPERTIES OF SOLIDS, LIQUIDS AND GASES BOB: Unscramble

Appearance & Particles Energy Compressibility Melting &
behaviour in a arrangement boiling
container points
A D. Particles are G. The very high J. high M. Moderate
disordered energy of the
and widely particles
SOLID
spaced causes random
& rapid

E. Particles H. The low K. very little N. High
closely energy of the
spaced & particles
arranged in causes them
LIQUID B a lattice. to vibrate
This explains about fixed
the positions
crystalline
appearance
F. Particles are I. The moderate L. virtually O. Low
disordered energy of the none
and closely particles
GAS C
spaced causes them
to move
randomly
Answers: SOLID __ __ __ __ __ LIQUID __ __ __ __ __ GAS __ __ __ __ __

http://
PROPERTIES OF SOLIDS, LIQUIDS AND GASES www.harcourtschool.com/
activity/states_of_matter/

Appearance & Particles Energy Compressibility Melting &
behaviour in a arrangement boiling
container points
Particles are The low energy virtually none High
closely of the particles
spaced and causes them to
arranged in a vibrate about
SOLID fixed positions
lattice. This
explains the
crystalline
appearance
Particles are The moderate very little Moderate
LIQUID and closely particles causes
spaced them to move
randomly
Particles are The very high high Low
GAS and widely particles causes
spaced random & rapid
movement


CHANGES OF STATE


ATOMS, ELEMENTS, COMPOUNDS & MIXTURES

P
U
R
E

Element Element Compound

N
O
T

P
U
R
E
Mixture Mixture
of elements of element with compound


Interactive Complete the mind map

All substances
X
.............. Not pure

...................
Elements ...................

Element
................ with Different
elements compound .................

Questions
1. Explain the difference between Co and CO
__________________________________________________________________
__________________________________________________________________

2. Explain the difference between O2 and 2O
__________________________________________________________________
__________________________________________________________________

Copy ATOMS, ELEMENTS, COMPOUNDS & MIXTURES

• An atom is a particle that cannot be made smaller by simple chemical methods.
• An element is a substance that contains only one type of atom.
• A compound is a substance that contains two or more types of atom chemically
joined together in a constant ration by mass.
• A mixture contains two or more different types of particle.
• A solution is a special mixture where the solid particles are spread evenly
throughout a liquid medium

All substances

Pure Not pure

Mixture
Elements Compounds

Element
Different with Different
elements compound compounds

Ex 3A: 1 to 4 - Answers only

SEPARATING
MIXTURES


SOLUTIONS PRE - TEST (out of 8)

Use the diagram, word list and prior knowledge to complete the cloze
exercise:

1. Salt added to water will form a ______________.

2. Salt is an example of an _________ solid
3. The ions present in salt are ___________ and _____________ .
4. Theses ions arrange themselves into a _____________.

5. Solids with __________ structures have a _____________ appearance. This
means the visible particles have __________ edges and __________ faces.

Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
lattice sodium ionic flat chloride sharp solution crystalline



exercise:
solution



Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
lattice sodium ionic flat chloride sharp crystalline



exercise:
solution
ionic


Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
lattice sodium flat chloride sharp crystalline



exercise:
solution
ionic
sodium


Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
lattice flat chloride sharp crystalline



exercise:
solution
ionic
sodium chloride


Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
lattice flat sharp crystalline



exercise:
solution
ionic
sodium chloride
lattice


Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
flat sharp crystalline



exercise:
solution
ionic
sodium chloride
lattice

Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
flat sharp crystalline



exercise:
solution
ionic
sodium chloride
lattice crystalline

Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
flat sharp



exercise:
solution
ionic
sodium chloride
lattice crystalline
sharp

Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list
flat



exercise:
solution
ionic
sodium chloride
lattice crystalline
sharp flat

Cl- Na+ Cl-

Na+ Cl- Na+

Cl- Na+ Cl-

Word list


SEPARATING MIXTURES
SOLUTIONS VIDEO


Solutions SEPARATING MIXTURES
http://phet.colorado.edu/new/simulations/sims.php?sim=Salts_and_Solubility
An animation showing how substances dissolve:

Solvent

Solute

Solution

Reading with exercises ->

SEPARATING MIXTURES

• Separation techniques based on the differences in the physical properties of the
substances making up the mixture.

Separation Why it can be separated using this
Type of mixture
technique technique
Decanting The particles in the mixture are different
Suspension (Liquid & sizes. Small liquid and solid particles
insoluble solid) pass through whilst larger solid particles
Filtration
do not

The solvent has a lower boiling point and
evaporates away. In the case of two
Solution (containing a Evaporation liquids that are mixed, the liquid with the
solvent & a solute or lower boiling point will evaporate away
two liquids that are
mixed) Based on evaporation but allows the
Distillation solvent or high boiling point liquid to be
kept

Different solvents have different
Solutions that contain solubility in the solvent used so they
Chromatography travel at different speeds alont the
many solutes
chromatography paper


ISOTOPES &
ATOMIC MASS


ATOMIC THEORY
History
1803 - Dalton’s model: “Atoms are indestructible spheres”
1911 - Rutherford: An atom is mainly empty space. It has a central dense,
positively charged nucleus. The nucleus is tiny compared
to the overall size of the atom.
1932 - Chadwick shows that neutrons exist

Atoms
Electron

+ Neutron
+

Proton

Part of Where Relative Electrical
atom found mass Charge
Proton nucleus 1 positive
Neutron nucleus 1 neutral
outside
Electron 0.0005 negative
nucleus

p31 & 32 - ESA -> Ex. 4A: Q.1 to 4 - answers only

ISOTOPES

16 17 18

O O O
8 8 8


ISOTOPES

Atoms with the same atomic number but different mass numbers.
Example
Below are the symbols of the common isotopes of Oxygen.

Notice that the mass numbers are different

16 17 18

O O O
8 8 8

Each isotope has 8 protons
8 neutrons 9 neutrons 10 neutrons
Each different isotope has
different numbers of neutrons


ATOMIC MASS
An isotope has a mass number.
An element that consists of different isotopes will have an atomic mass.

Ex 4B Q.1 to 3 - answers only

ATOMIC MASS

The atomic mass of an element is the weighted average of the mass numbers of all
the isotopes in that element.


ATOMIC MASS


Example
A naturally occurring sample of Copper has 3 atoms of 63
Cu to each one atom of
65
Cu:

63
Cu 63
Cu 63
Cu 65
Cu


ATOMIC MASS


Example
65
Cu:

Atomic mass = 63 + 63 + 63 + 65
63
Cu 63
Cu 63
Cu 65
Cu 4
= 63.5
(or “3 x 63 + 65”)


ATOMIC MASS


Example
65
Cu:

Atomic mass = 63 + 63 + 63 + 65
63
Cu 63
Cu 63
Cu 65
Cu 4
= 63.5
(or “3 x 63 + 65”)

Chlorine is another element which consists of different isotopes. It has an atomic
mass of 35.5


ATOMIC MASS


Example
65
Cu:

Atomic mass = 63 + 63 + 63 + 65
63
Cu 63
Cu 63
Cu 65
Cu 4
= 63.5
(or “3 x 63 + 65”)

Chlorine is another element which consists of different isotopes. It has an atomic
mass of 35.5

Most elements consist mainly of one isotope and therefore their atomic mass is
close to a whole number.


ESA p41 Boron is unshaded because it does not covalently bond with itself??

LEWIS
STRUCTURES

ELECTRON CONFIGURATION

• Electrons around the nucleus of the atom have different levels of energy:
• High energy electrons move in regions which are further away from the nucleus
than low energy electrons.

• Greater stability is achieved when the outer energy level is fully occupied by
electrons (usually 8) - this is the octet rule.

Ion formation occurs according to this rule

Example Sodium atom GREATER
Sodium ion
STABILITY

Na Na+

1 electron is lost

Note: Inert gases are stable because the outer level is fully occupied by electrons

ATOM MODELS

Models are used to explain things that we can’t see and/or understand.

Showing only the outer electrons (valence electrons) is a useful model.

Examples - “electron dot diagrams”

Electron configuration is 2.5 but only the 5 valence electrons
N are shown
(the 7 protons and 7 neutrons are not shown in this model)

Electrons are displayed as dots and shown in pairs as they are
thought to occupy the same region in an energy level.
Cl


“CAN YOU SEE THE PATTERN?”

Metal
Key
Borderline but more non - metal

Non - metal

“Which atoms will bond covalently to form molecules?”


COVALENT BONDING

Covalent bonds are formed between non-metal atoms. The bond is
based on the mutual attraction of 2 different positively charged nuclei to the
same pair of negatively charged electrons.

Molecules are formed.

Example: Chlorine, Cl2
Chlorine does not normally exist as individual atoms. Two chlorine atoms pair up to
make a molecule. A pair of electrons is shared between the two atoms:

Each chlorine atom
7 valence
Cl + Cl Cl Cl now has 8 valence
electrons
electrons

A lone pair of electrons A shared pair

“The octet rule is nearly always obeyed except where Hydrogen is involved
in a covalent bond. The outer energy level of hydrogen is fully occupied
when it contains 2 electrons. Hydrogen obeys the duet rule”


LEWIS STRUCTURES

The chlorine molecule drawn (above) is an example of a Lewis structure

Other Lewis structures

Water H2O
O H

H

Hydrogen chloride HCl H Cl

Note
Both the octet and duet rules are both obeyed in the examples (above)
The attraction between atoms is called a bond
A bond can be drawn as a line:

H
H - Cl
O O


DOUBLE BONDS

Sometimes, in order to obey the octet rule, two atoms will need to share
two pairs of electrons.
This TWO shared pair of electrons forms the basis of a double bond.

Examples
Silicon dioxide, SiO2 contains 2 double bonds

O Si O O Si O

TWO pairs are shared The octet rule is
satisfied for each atom
Carbon tetrachloride CCl4 contains only in the molecule
single bonds
Cl Cl

Cl C Cl Cl C Cl

Cl Cl


TRIPLE BONDS

When three pairs of electrons are shared, a triple bond is formed.

Example
Propyne, C3H4

H

H C C C H

H
THREE pairs are shared

Note
• Two atoms joined by a double bond are closer together than two atoms joined by a
single bond. The double bond is shorter and stronger but allows the molecule to be
more reactive because there are more electrons concentrated there.
• The same applies for a triple bond compared to a double bond.

IONIC
SOLIDS

IONIC SOLIDS


IONIC BONDING

Ionic bonds are formed between metal and non-metal ions.
The bond is based on the attraction between positively and
negatively charged ions. Ionic compounds are formed.

Cl- Na+ Cl- “Negative ions are
called anions”

Na+ Cl- Na+

“Positive ions are
Cl- Na+ Cl- called cations”

Note
• Because they are oppositely charged, Sodium and Chloride ions are attracted to
each other.
• This attraction extends in 3 dimensions and results in a huge cubic arrangement
of ions. This arrangement is called a lattice.

This is Ann Ion.


This is Ann Ion.
She’s unhappy and
negative.


+ +

This is Ann Ion.
She’s unhappy and
negative.


+ +

This is Ann Ion. This is a cat-ion.
She’s unhappy and
negative.


+ +

This is Ann Ion. This is a cat-ion.
She’s unhappy and He’s a “plussy” cat!
negative.


PERIODIC
TRENDS

THE PERIODIC TABLE

(numbers given to columns)

3 4

(numbers given to rows) Key: show relative atomic size.
Size increases across a row &
decreases down a column.

Note
• There are columns of less reactive metals (transition elements)
between groups 2 and 13
• The dotted line separates metals from non-metals

REACTIVITY OF METALS

The reactivity of a metal is a measure of the metal’s ability to participate in a
chemical reaction.

Metals react when their atoms lose their valence electrons. The easier the electrons
are lost, the more reactive they will be.

Decreasing reactivity

As we move down As we move across a
the group the Li Be period (left to
valence electrons get Lithium Beryllium right),the positive
Increasing reactivity

further from the 2.1 2.2 nucleus increases in
nucleus so they charge so the
become easier to attractive force on
remove.
Na Mg Al the valence electrons
Sodium Magnesium Aluminium increases. Valence
2.8.1 2.8.2 2.8.3 electrons become
Highly more difficult to
reactive
Ca remove.
K
Potassium Calcium
2.8.8.1 2.8.8.2


REACTIVITY OF NON-METALS

The reactivity trends of non-metals can be explained by the ease with which
they can gain electrons to form ions.

As we move across a period (left to right),the
size of the atom decreases so the attractive
force on valence electrons increases.
Electrons are gained more easily.
He
Increasing reactivity Helium
2
Highly

B C N O Ne

Decreasing reactivity
reactive

Boron Carbon Nitrogen Oxygen
F Neon
Fluorine
2.3 2.4 2.5 2.6 2.7 2.8

Si P S Cl Ar
Silicon Phosphorus Sulphur Chlorine Argon
2.8.4 2.8.5 2.8.6 2.8.7 2.8.8

As we move down the group the atoms increase
in size as the number of energy levels increases.
It becomes more difficult to gain electrons.

PHYSICAL
PROPERTIES

Ionic vs covalent FORMULAE Comparing & contrasting

Examples: Sodium Chloride, NaCl and Carbon dioxide, CO2

O C O

Cl- Na+ Cl-
• a molecule - a small particle

Na+ Cl- Na+ • a group of atoms joined.
2 atoms of oxygen joined to 1
atom of carbon
Cl- Na+ Cl-

O C O
• a lattice (a huge group of
positive and negative ions joined
to each other in an organised
The formula for an ionic compound
way)
has quite a different meaning to the
• Sodium and chloride ions are formula for a covalently bonded
present in a 1:1 ratio compound.


Ionic vs covalent PHYSICAL PROPERTIES Comparing & contrasting

Properties Sodium Chloride Carbon dioxide
White solid at room
State Colourless gas
temperature
Melting point high low
Solubility in water High low
None when solid but
conducts well when in
Electrical conductivity None
the molten state or
when in solution


PHET animation showing solubility


Ionic vs covalent PHYSICAL PROPERTIES AND STRUCTURE Comparing &
contrasting

Ionic compounds are formed by the strong attraction between positive and
negative ions. This makes it difficult to separate the ions by heating the compound
so most ionic compounds are solid at room temperature.

Covalently bonded compounds usually have very weak forces of attraction
between molecules since each molecule is neutral. Separating the particles
(molecules) is easy. Most of them are already separated at room temperature
(making them solids or liquids).

Note - it is possible to have molecules that are ions - dealt with later

Solubility requires water molecules to surround each particle of a compound. Water
molecules have a positive end and a negative end. The water molecule’s negative end
will be attracted to a positive ion and its positive end to a negative ion. Because
molecules are uncharged this attraction to water molecules does not take place.

An electric current is the flow of charged particles. Ionic solids contain charges that
can be free to move and so can conduct electricity. Covalently bonded compounds can
not because they consist of molecules that are neutral.


ESA
EXERCISES

5. IDENTIFY COMPOUNDS
Term Definition Example

Elements have only one kind of atom.

have two or more types of
Compounds atom that are chemically
joined
have elements and/or “Remember
Mixtures compounds that are not this!!!”
chemically joined
Elements can exist as molecules. Molecules are groups of atoms that are joined
Examples
Oxygen, O2 Hydrogen, H2 Helium, He Chlorine, Cl2 Carbon, C
Elements

Water, H2O Hydrogen Chloride, HCl Carbon Dioxide, CO2
Compounds


The following table is not correct UN-MIXING THE TABLE
Copy the following table but match the term with its correct diagram

A. mixture of 1.
(i) Hydrogen and
different
elements Oxygen

B. mixture of 2.
(ii) Water and
different
compounds Hydrogen Chloride
3.
C. mixture of an (iii) Oxygen and
element with
a compound water
The following word equations describe
Answers _____ ______ ______
chemical reactions. CIRCLE THE
_____ ______ ______ COMPOUNDS

_____ ______ ______ A chemical reaction is a non-reversible change
in which new substances are formed.

(a) Aluminium + Iodine ----> Aluminium Iodide

(b) Sulfur + Oxygen ------> Sulfur Dioxide

Demo MAKING A COMPOUND

Iron heated with sulphur

test-tube

mixture of powdered
sulphur and iron

Bunsen burner (blue flame)

Appearance of the elements before heating:

Iron _______________________________________________________

Sulphur _______________________________________________________

Appearance of the compound formed after heating:
______________________________________________________________

Name of compound formed: _______________

MAGNETIC PROPERTIES

1 2
Magnet

Sulphur
Iron filings

3
Observations:
___________________________________
___________________________________
___________________________________
Iron Sulphide
(the product) ___________________________________
___________________________________
___________________________________
___________________________________

Drawing A CLOSER LOOK

P
U
R
E

Element Element Compound

N
O
T

P
U
R
E
Mixture Mixture
of elements of element with compound


MIND MAP

All substances

.............. Not pure

...................
Elements ...................

Element
................ with Different
elements compound .................

Questions
1. Explain the difference between Co and CO
__________________________________________________________________
__________________________________________________________________

2. Explain the difference between O2 and 2O
__________________________________________________________________
__________________________________________________________________

6. EXPLAIN HOW MANY ATOMS ARE PRESENT IN THE
FORMULA OF A COMPOUND
Study the pictures below and copy and complete the sentences below:

Oxygen, O2
Oxygen is an element, it consists of two oxygen atoms
that are chemically joined.

Hydrogen Chloride, HCl Hydrogen Chloride is a compound. It exists as
molecules. The molecules are not joined to each other
and move around randomly. Each molecule consists of
one atom of hydrogen and one atom of Chlorine.

Water, H2O Water is a compound. It exists as molecules. The
molecules are not joined to each other and move
around randomly. Each molecule consists of one atom
of oxygen and two atoms of Hydrogen. Each molecule
is shaped like a “V”.

This information can be summarised in a table. Complete the table (below):
Name of the molecule Is it a compound Number of atoms


Process for counting up atoms
1. Start inside the bracket.
2. Add up the numbers behind each symbol. No number counts as one atom.
3. Multiply this number by the number behind the bracket.
4. Add this to any other atoms in the formula.
5. Then multiply this total by the number in front of the formula.
1 EXAMPLE

2 Cu(OH)3
2
3
1 O and 1 H 4
x3 = 6
= 2 Atoms
= 7 5
1 Cu = 14
x2

OTHER EXAMPLES
How many atoms of each element are there in each of the following compounds:
KCl _____ KNO3 _____ Ca(OH)2 _____ AlPO4 _____
CuCO3 _____ CuSO4 _____ 2 Al2(SO4)3 _____ FeCl3 _____

Zn(NO3)2 _____ PbI2 _____ 3HNO3 _____ Na2CO3 _____

COUNTING ATOMS Count the atoms in the
following formulae:

INSERT ANOTHER EXERCISE/PUZZLE


EX
O ER
R CI
HW S
K ES

ELEMENTARY CROSSWORD


PUT THOSE ELECTRONS IN THEIR PLACES
1. COMPLETE THE TABLE (BELOW) 2. Draw shell diagrams for the following atoms:
(i) Be (ii) F (iii) Ne (iv) Ar Use the
Metal atom Non-metal atom Use the spaces
spaces providedprovided

C: 2, 4 Cl: 2, 8, 7 (i) Be (ii)F
Mg: 2, 8, 2 N: 2, 5

Li: 2, 1 Ar: 2, 8, 8

Be: O:

Ca: S:

Al: F:

Na: P:

Si: B:

(iii) Ne (iv) Ar


COMPOUND FRACTURE
For each of the following descriptions , write the word “mixture” or “compound” to
describe which category it fits into:
• Properties depend on the amount of each particle present ________________
• Consist of one type of particle only ________________
• Have a variable collection of elements ________________
• Have a fixed ratio of different elements ________________
• Consist of several different types of particle ________________
• Properties are always the same ________________

Each of the following is a compound made up of two elements combined. Starting at
sodium chloride, connect it to another compound that contains one of its elements.
Do the same for the second compound until you connect to lead sulfate.

Sodium Calcium Magnesium Aluminium
Chloride Sulfide Oxide Bromide

Magnesium Sodium Potassium
Iodide Fluoride Oxide

Calcium Potassium Aluminium Lead Sulfide
Bromide fluoride Iodide


Complete the table:

Chemical formula Total number of atoms in each formula


ELEMENT CUBES Each side of the cube:
1. Name & symbol of
Each student allocated a different element. Put into
letter box. Reallocate. element
Research -> element cube (book computers, 2. Uses of the element
ﬁnish for Hwk) 3. Classification (metal/non-metal)
4. Physical properties
(colour, s/l/g)
5. History - discovery
6. Extraction

138


Name these scientists:
1. The Greek philosopher who first thought of the idea of atoms _________________
2. The English clergyman who thought atoms were like tiny billiard balls of different
sizes. ______________________________________
3. The English physicist who discovered the electron. ___________________
4. The New Zealander who discovered that the atoms have a nucleus surrounded by
electrons. ______________________________________
5. The English physicist who found that the atomic number is the same as the number
of protons _____________________________________
6. The English physicist the proof of existence of neutrons ______________________

ST
AR
TE
R S

READING SEPARATION OF MIXTURES


EXERCISES SEPARATION OF MIXTURES


SEPARATING MIXTURES

A solution is made by mixing a solid and a liquid.
Initially:

Particles in the solid are ___________ around fixed positions with the liquid
particles moving about _____________ .

After a while:

_____________ forces between liquid particles and solid particles allow the
liquid particles to pull the solid particles away from their fixed positions
to __________ amongst the liquid ones. The solid particles in a solution are
very s _ _ _ _ .

A solution is a mixture of a solid in a liquid where the solid
particles are very small and are evenly spread amongst the
liquid particles.


SEPARATING MIXTURES

A suspension is __________ from a solution because the solid particles in the
suspension are ________ and _________ to the bottom. Because the solid particles
are ________ it is not possible to _______ through a suspension.

Word List: settle, different, bigger, see

Examples of suspensions
in everyday life

Animation: (Filtration) http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/
elements_com_mix_8.shtml

SEPARATING MIXTURES

Term Definition

A. solution 1. the substance that does the dissolving

B. solute 2. the substance that dissolves

3. a mixture of a solid with a liquid where the solid particles
do not spread evenly through the liquid but instead sink to
C. solvent
the
bottom.

4. a special mixture that looks and behaves like a single
D. suspension
substance

A _____ B _____ C _____ D _____


SEPARATING MIXTURES

Word Meaning

Dilute

Concentrated

Solubility

Saturated

1. When sugar is mixed with water it ____________ . This shows the sugar is
____________ in water.
2. Sand is ______________ in water.
3. Salty water is a _____________, bud muddy water is not.
4. In salt water, the salt is the ____________, and the water is the ____________ .
5. The solute in a solution does not settle out, but the solid in a _______________
does.
6. A solution that can dissolve no more solute is ____________ .
7. Most solids are more ___________ in hot water than in __________ water.


SEPARATING MIXTURES Lab 8

Filtration and decanting are used to make
milk glue

Decanting into a small beaker. Try not Filtering out the curds. The clear
to lose any of the curds. The small liquid (or filtrate) goes down the
beaker will ____________any that get sink. The __________ remains in
past the stirring rod. the filter paper.

Word list
Funnel Curds Beaker Filter paper catch residue Sink Stirring rod

SEPARATING MIXTURES

• Evaporation occurs when a ______ changes into a ____. Word List
• Evaporation is a good way of separating a solution because cool
_____________________________________________________
gas
_____________________________________________________
• If you separate a solution but also want to keep the liquid then
condensation

you have to _____ it. This process is called ____________. liquid
• Condensation occurs when a _____ changes into a _______.

Example

Write a short paragraph to explain what is happening in the above example

_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________


SEPARATING MIXTURES

Word List
Solution _____________ distillate
(Ethanol vapour
and water)
condenser
boils
_____________ thermometer
liquid
_____________ round bottom flask
water
cooled

_____________

We were able to separate the ethanol from the water because the ethanol
_____________ at a lower temperature than the ________. The ethanol
_________ passes into the ____________ where it is ___________ to
become a __________ .

http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/elements_com_mix_8.shtml

SEPARATING MIXTURES

Mixture Method of separation

Add _________. The soluble substance ____________ . The
____________ substance does not dissolve. Filtering the
Salt and sand mixture will collect the _____________ substance in the
filter paper. This is called the ____________ .

hold a magnet to the mixture. The _____________
Iron filings and
substance collects on the magnet. The other substance is left
sulphur
behind.
Add water. The sawdust __________. The sand _________.
You can scoop the sawdust off the top.
Sawdust and sand

Swirling the mixture in a shallow pan. The ___________
mud and sand fly out of the pan. The ______________ gold
Gold, mud and sand
gets left behind.

Word List: sinks heavier water dissolves insoluble lighter residue
magnetic floats

CHEMICAL BINGO
From your periodic table of elements, choose any 14 symbols from the first 20 and fit them
into the unshaded squares. When the name of the element is called out cross it out using a
pen. When all the symbols have been crossed off, call “bingo”.

CHEMICAL BINGO
From your periodic table of elements, choose any 14 symbols from the first 20 and fit them
into the unshaded squares. When the name of the element is called out cross it out using a
pen. When all the symbols have been crossed off, call “bingo”.


QUICK QUESTIONS

1. What is the name of the particle that cannot easily be made smaller?

2. Name 2 objects in the room that contain carbon.

3. Air is made up mainly of which element?

4. Explain the difference between an element and a compound.

5. Name one particle that can be found inside the nucleus of the atom. (Challenge!)


THE TE PUKE KID

The Te Puke kid mounted his trusty steed, old (Au) ________. He strapped
his shooting (Fe) __________ to his side and headed out from the bright
(Ne) _________ lights. He was determined to rob the stage of its precious (U)
_________ load. He inhaled a deep breath of (O) ___________ and coughed on the
(S) ____________ from the nearby factories. It really was hot, the (Hg)
___________ was rising. He took a drink of (H2O) __________ and spat as he tasted
the (Cl) ___________ .

He rode north, his bones aching from (Ca) __________ deposits built up from years
of riding the (Zn) trail. Overhead he saw the stage coach. It was guarded by an old
sheriff with a (Sn) ___________ badge. “Stop”, the kid yelled, “or I’ll fill you full of
(Pb) _________.” The sheriff went for his gun but was too slow. Kid’s gun blazed like
flaming (Mg) ________________ and the (Cu) ____________ fell to the ground.
Anyone who drew on the kid should have known that his life was not worth a plugged
(Ni) ____________ . A pretty (Pt) ________________ blonde on the stage screamed
as the Kid pulled out some (N) _____________ compounds to blow the strongbox.

Suddenly a shout rang out. “Hi Ho (Ag) ____________” . A masked man on a white
horse raced across the (Si) _______________ sands like (Na) ___________
skittering on water. There’s a (Rn) __________, “ he cried. The Kid was captured and
was put behind (Co) ______________ steel bars.

Don’t let you life be a (C) ______________ of the Kid’s. Learn your Chemistry!!

QUICK TEST - 1 Name _________________

1. What is the name of the particle that cannot easily be made smaller?
_____________________
2. Name 2 objects in the room that contain carbon. ________ , __________
3. Air is made up mainly of which element? _________
4. Explain the difference between an element and a compound.
________________________________________________
________________________________________________
5. Write the symbols for the following elements:
(a) Lithium ____ (b) Boron ____ (c) Fluorine ____ (d) Argon (e) Silicon ____
(f) Phosphorus _____ (g) Chlorine ____
(h) Sodium _____ (i) Potassium ____
6. Name the following elements:
(a) H __________(b) He __________ (c) Be __________
(d) C __________ (e) N __________ (f) O __________
(g) Ne __________ (h) Mg __________ (i) Al __________
(j) S __________(k) Ca __________


QUICK QUESTIONS

Test yourself by copying and answering the FIRST FIVE QUESTIONS into the back
of your book
1. Explain why elements are like the letters of the alphabet.

2. Elements are made up of only ......... ............. .... ........... .

3. A compound (like an element) is a ............ substance but a compound will
contain ...(several words)....... which are
............... .

4. What is the main difference between a compound and a
mixture.

5. Explain why air is a mixture of elements and compounds.

Explain the following statement: “The nucleus is like
a flea in the Yankee Stadium”


THE LANGUAGE OF THE PERIODIC TABLE

The atomic number
The atomic number of an atom is the number of ..................
in the ..................... of that atom.

An atom of the same element will always have the same
................. number.

The number of electrons
Because protons are positively charged and electrons are
negatively charged and an atom is electrically neutral then
the number of electrons surrounding an atom is always be ............. ..... the
number of protons in the nucleus.

The mass number
The mass number is equal to the number of .................. plus
the number of ..................... .


TE
M AC
AT H
ER ER
IA
L

Material World (level 5)
• Properties of Materials MW props: Investigate the physical and chemical properties of different groups of substances.
For example acids and bases, fuels and metals. Distinguish between pure substances and mixtures and between
elements and compounds.
• Structure of matter MW struct: Describe the structure of the atoms of different elements. Distinguish between an
element and a compound, a pure substance and a mixture at particle level.
• Chemistry and society MW soc: Link the properties of different groups of substances to the way they are used in
society or occur in nature.
SCHEME


BC HISTORY OF THE ATOM As you watch the video (22 min) complete the
following timeline with the exact year, name of the
person with the idea and the explanation of the theory
Name Explanation
400 Ancient babylon - Gold from other elements (Zinc & Copper = Bronze ...)
Ancient Greece - (5th Cent BC) Alchemy - All matter = “Fire, water, air & earth”

384-322 Aristotle - “Atomless view”
Empedocles & Leucippus - believed in atoms
342

300 Epicurus - also believed in atoms, “ God is the prime mover”

270

200

100
95 Leucretius - “Romans didn’t care” about science (Alchemy) = The Dark Age of Alchemy

0

0
AD

500

1000

1500
1641 Pierre Gassandi - “Atoms exist but they are God’s building blocks
1661 Boyle & Newton - Gases are particles that move --> Pressure
1774 Joseph Priestly - “When things burn they lose mass”
Lavoisier - Discovered air. Metals take up Oxygen when burnt -> an increase in mass (Mercury)
1803 Dalton - Elements exist as atoms. Different atoms => different atomic weights. Combinations in
different ratios. In 1808 “Atomic theory” was published by Dalton. No alchemy & no
2000 atomic conversions

Atomic Structure

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