3. Main Ideas
Periodic trends in the properties of atoms allow us to
predict physical and chemical properties.
The periodic table evolved over time as scientists
discovered more useful ways to compare and
organize elements.
Elements are organized into different blocks in the
periodic table according to their electron
configurations.
Trends among elements in the periodic table include
their size and their ability to lose or attract electrons
4. Development of the
Modern Periodic Table
Objectives:
Trace the development of the periodic
table
Identify key features of the periodic table
5. Development of the
Periodic Table
In the 1700’s, Lavoisier compiled a list of
all the known elements of the time.
33 elements
6. Development of the
Periodic Table
The 1800s brought large amounts of
information and scientists needed a way
to organize knowledge about elements.
of electricity – break down
Advent
compounds
Development of the spectrometer –
identify newly isolated elements
7. Development of the
Periodic Table
The 1800s brought large amounts of
information and scientists needed a way
to organize knowledge about elements.
revolution – new chemistry
Industrial
based ingredients and compounds.
70 known elements by 1870
8. Development of the
Periodic Table
The 1800s brought large amounts of
information and scientists needed a way
to organize knowledge about elements.
JohnNewlands proposed an
arrangement where elements were
ordered by increasing atomic mass.
9. Law of Octaves
Newlands (1864)
noticed when the
elements were
arranged by
increasing atomic
mass, their
properties repeated
every eighth
element.
10. Law of Octaves
Octaves was used
due to the musical
analogy, but was
widely dismissed.
Some elements
didn’t follow the
pattern
11. The Periodic Table
Meyerand Mendeleev both demonstrated
a connection between atomic mass and
elemental properties.
12. The Periodic Table
Mendeleev’s Table – A Russian scientist
– gets the most credit because he
published first.
Arranged elements by increasing mass and
columns with similar properties.
Predicted the existence and properties of
undiscovered elements.
Still some inconsistencies.
13. The Periodic Table
Moseley discovered that each element
had a distinct number of protons.
Once rearranged by increasing atomic
number, the table resulted in a clear
periodic pattern.
14. The Periodic Table
Periodic repetition of chemical and
physical properties of the elements when
they are arranged by increasing atomic
number is called periodic law.
15.
16. The Modern Periodic
Table
The modern periodic table contains boxes
which contain the element's name, symbol,
atomic number, and atomic mass.
17. The Modern Periodic
Table
Rows of elements are called periods. (total of 7)
Columns of elements are called groups. (total of
18)
Elements in groups 1,2, and 13-18 possess a
wide variety of chemical and physical properties
and are called the representative elements.
Elements in groups 3-12 are known as the
transition elements .
18. Types of Elements
Elements are classified as metals, non-metals, and
metalloids.
Metals are made up of most of the representative
elements and all of the transition elements.
They are generally shiny when smooth and clean,
solid at room temperature, and good conductors of
heat and electricity.
Most are Ductile and Malleable –
Ductile – the ability to be drawn into wire.
Malleable – the ability to be pounded into sheets
19. Types of Elements
Elements are classified as metals,
non-metals, and metalloids.
Alkali metals are all the elements in group 1,
except hydrogen, and are very reactive.
Alkaline earth metals are in group 2, and are also
highly reactive.
21. Types of Elements
The transition elements (groups 3 - 12) are
divided into transition metals and inner
transition metals.
The two sets of inner transition metals are
called the lanthanide series and actinide series
and are located at the bottom of the periodic
table.
Lanthanides are phosphors – elements that
emit light when struck by electrons.
22. The Modern Periodic
Table
Non-metals are elements that are generally
gases or brittle, dull-looking solids, and poor
conductors of heat and electricity.
Group 17 is composed of highly reactive
elements called halogens.
Group 18 gases are extremely unreactive and
commonly called noble gases.
23. The Modern Periodic
Table
Metalloids have physical and chemical
properties of both metals and non-metals, such
as silicon and germanium. They are found
along the stair step of the table starting with
Boron
24.
25. Questions
What is a row of elements on the periodic
table called?
A. octave
B. period
C. group
D. transition
26. Questions
What is silicon an example of?
A. metal
B. non-metal
C. inner transition metal
D. metalloid
28. Classification of the
Elements
Objectives:
Explain
why elements in the same group
have similar properties.
Identify
the four blocks of the periodic
table on their electron configuration.
29. Organizing the Elements
by Electron Configuration
Electron configuration determines the
chemical properties of an element.
Recallelectrons in the highest principal
energy level are called valence
electrons.
30. Organizing the Elements
by Electron Configuration
All
group 1 elements have one valence
electron.
All
group 2 elements have two valence
electrons.
32. Organizing the Elements
by Electron Configuration
The energy level of an element’s valence electrons
indicates the period on the periodic table in which it
is found.
The number of valence electrons for elements in
groups 13-18 is ten less than their group number.
After the s-orbital is filled, valence electrons occupy
the p-orbital.
35. Organizing the Elements
by Electron Configuration
The d-block contains the transition metals and is
the largest block.
There are exceptions, but d-block elements usually
have filled outermost s orbital, and filled or partially
filled d orbital.
The five d orbitals can hold 10 electrons, so the d-
block spans ten groups on the periodic table.
36. Organizing the Elements
by Electron Configuration
The f-block contains the inner transition metals.
f-block elements have filled or partially filled
outermost s orbitals and filled or partially filled 4f and
5f orbitals.
The 7 f orbitals hold 14 electrons, and the inner
transition metals span 14 groups.
38. Periodic Trends
Objectives:
Compare period and group trends of
several properties.
Relate period and group trends in atomic
radii to electron configuration
39. Atomic Radius
Atomic radius – is determined by the amount of
positive charge in the nucleus and the number of
valence electrons of an atom. It is usually
measured in picometers (10-12).
For metals, atomic radius is half the distance
between adjacent nuclei in a crystal of the
element.
For diatomic nonmetals, the atomic radius is the
distance between nuclei of identical atoms.
43. Atomic Radius
The periodic trend: decreases from left to right
(periods) and increases top to bottom (groups)
due to the increasing positive charge in the
nucleus.
45. Atomic Radius
Atomic radius generally increases as you move
down a group.
The outermost orbital size increases down a
group, making the atom larger.
Valence electrons are not shielded from the
increasing nuclear charge because no additional
electrons come between the nucleus and the
valence electrons.
46. Ionic Radius
Ions – atom(s) that gain or lose one or more electrons
to form a net charge.
Ionic radius is the radius of a charged atom.
When atoms lose electrons and form positively
charged ions, they always become smaller.
Lost electrons are usually valence electrons and
could leave the outer orbital empty and therefore
smaller.
Electrostatic repulsion between remaining
electrons decreases and pulls closer to nucleus.
47. Ionic Radius
When atoms gain electrons and forms a
negatively charged ion, they become larger.
Increased electrostatic repulsion increases
distance of outer electrons.
49. Ionic Radius
Periodic Trend: radius of an ion decreases from
left to right (periods) until charge changes and
then the radii increases dramatically. After the
change, the radius continues to decrease.
Ionic radii increases top to bottom (groups) until
change in charge.
51. Ionization Energy
Ionization energy is the energy needed to
remove an electron from the positive charge of
the nucleus of a gaseous atom. (how strongly
a nucleus holds on to an electron.)
First
ionization energy is the energy required to
remove the first electron.
Removing the second electron requires more
energy, and is called the second ionization
energy.
52. Ionization Energy
Atoms with large ionization energies have a
strong hold of its electrons and are less likely
to form positive ions.
Atoms with low ionization energies lose their
outer electrons easily and readily form positive
ions.
Theionization at which the large increase in
energy occurs is related to the number of
valence electrons.
54. Ionization Energy
Periodic Trend: First ionization energy increases
from left to right across a period. First ionization
energy decreases down a group because atomic
size increases and less energy is required to
remove an electron farther from the nucleus.
55. Ionization Energy
The octet rule states that atoms tend to gain,
lose or share electrons in order to acquire a full
set of eight valence electrons. The octet rule is
useful for predicting what types of ions an
element is likely to form.
60. Questions
The ionic radius of a negative ion becomes
larger when:
A. moving up a group
B. moving right to left across period
C. moving down a group
D. the ion loses electrons
71. Key Concepts
The elements were first organized by increasing
atomic mass, which led to inconsistencies. Later,
they were organized by increasing atomic
number.
The periodic law states that when the elements
are arranged by increasing atomic number, there
is a periodic repetition of their chemical and
physical properties.
The periodic table organizes the elements into
periods (rows) and groups (columns); elements
72. Key Concepts
Elements are classified as either metals, nonmetals, or
metalloids.
The periodic table has four blocks (s, p, d, f).
Elements within a group have similar chemical properties.
The group number for elements in groups 1 and 2 equals
the element’s number of valence electrons.
The energy level of an atom’s valence electrons equals its
period number.
73. Key Concepts
Atomic and ionic radii decrease from left to right
across a period, and increase as you move down a
group.
Ionization energies generally increase from left to
right across a period, and decrease as you move
down a group.
The octet rule states that atoms gain, lose, or share
electrons to acquire a full set of eight valence
electrons.
Electronegativity generally increases from left to right
74. Chapter Questions
The actinide series is part of the
A. s-block elements.
B. inner transition metals.
C. non-metals.
D. alkali metals.
75. Chapter Questions
In their elemental state, which group has
a complete octet of valence electrons?
A. alkali metals
B. alkaline earth metals
C. halogens
D. noble gases
