1. Elements ,compounds, and
mixtures
Juwarto, S.Pd
Grade VII Semester 1
115 Junior high Schools

3. Basic Competency:
To understand the element, compound and
mixture.
Standard Competency:
Describes concept of element, compound and
mixture.
Objectives:
• To describe the characteristics of elements,
compounds, and mixtures
• To classify matters into elements ,compounds
,and mixture

4. • Matter - anything that has mass and take any space

5. • Element is single matter that cannot be broken
down into simpler matter by chemical methods.
• There are 116 known elements. Of these 92 are found
in the Earth (natural). The other 24 elements have
been made by scientist in laboratories (manmade).
Examples of element:
silver
Fluorine
Gold
Aluminium Mercury

6. The Symbol of element
• Jons Jacob Berzelius proposed alphabets as the symbols of
each element.
• All of elements use symbol. These symbols were taken one or
two letters from their old Latin or Greek name.
Example: Au is the Latin word of gold “Aurum”.
• Rules of writing element symbols:
1. If an element is symbolized by one letter, it must be capital
letter, for example oxygen (O), hydrogen (H), carbon (C).
2. If an element is symbolized by more than one letters, the first
letter must be capital letter followed by small letter, for
example zinc (Zn), gold (Au), copper (Cu).

7. Think Time
• What are the chemical symbols of the following
elements?
a) Bromine f) Mercury
b) Silver g) Calcium
c) Uranium h) Natrium
d) Antimony i) Potassium
e) Tungsten j) Helium
• What are the names of the elements with the
following chemical symbols?
a) Si f) Ni
b) P g) Al
c) Sn h)Mg
d) Pb i) Zn
e) Au f) S

8. Classification of the Elements
 Classification of elements by state
– Elements can be classified by their
physical state at room temperature
• Solid (of the 92 natural element, 79 are
solids)
• Gas (of the 92 natural element, 11 are
gases)
• Liquid (of the 92 natural element, 2 are
liquid)
Chlorine gaseous Silver solid element
Bromine liquid element
element

9.  Classification of elements as metal and non
– Elements are classified as metals and non-metals, depending
metals
on how well they conduct electricity and heat.
– Metals are good conductors and Non-metal very poor
electrical conductors.
– Some elements are classified as Metalloids (or semi-metals).
Metalloids have properties between those of metals and non
metals.
Metalloid
metal Non - metal
lead
carbon sulphur
boron
mercury
silikon
copper
chlorine neon
Noble gases

10. Properties Metals Non-metals
Ability to conduct Good conductor Poor conductor
heat and electricity (except carbon)
Densities, melting Usually solids Usually liquid and
and boiling point (except gases with low
mercury), high densities, low
densities, high melting points
melting points and boiling points
and boiling
points
Appearance Usually hard and Usually soft and
shiny dull
Are they Yes No
malleable?
(mudah ditempa )

11.  Classification of elements as in the periodic table

12. What are elements made of?
• Atoms
 An atom is the smallest unit of an element, having
properties of that element.
 The atoms of one element are different from the
atoms of any other element. For example, all
hydrogen atoms are the same and are different
from atoms of carbon or iron.
• Molecules
 Most gaseous elements form molecules comprising
two atoms.
Example:
– Oxygen (O2), N2 Gases
– Hydrogen (H2),
– Nitrogen (N2),
N + N N N
– Chlorine (Cl2)

13. Post test
Answer this question.
• Define an element.
• State the names and symbols of
some common elements.
• Describe ways of classifying the
elements.
www.chem4kids.com

14. • Compound is a substance containing two or more
elements chemically joined together.
• Compound is a single matter that cannot be
broken down by physical separation.
• The compound can only be broken down into its
elements by a chemical reaction.

15.  Ifelements combine together, they will
completely change.
For example:
 Water (H2O) is a compound made up of Hydrogen
and Oxygen.
Hydrogen and Oxygen are colourless gases, and
the compound water is colourless liquid
H H + O
H
O H

16. What are Compound made of?
 Molecules is the smallest particle of a compound.
 A compound contain only one kind of molecule.
 Molecule is a group of two or more atoms
chemically joined together.

17. The chemical formula of a molecule shows the
number and kinds of atoms contained in it.
The chemical formula for water is
Symbol of
atom
The amount of
atoms present in
one molecule
This formula tells us that a water molecule
contains 2 hydrogen atoms and 1 oxygen
atom

18. 1. State the number of atoms and name the
kinds of atoms shown by each formula
a. Alcohol, C2H5OH
b. Refined sugar, C12H22O11
c. Sulphuric acid, H2SO4
d. Sulphur dioxide, SO2
e. Glucose, C2H12O6
f. Urea, CO (NH2)2

19. Names of compound
• Many compound contain a metal and a non-metal. The
metal part usually comes first, followed by the non-metal
part.
– For example: NaCl (sodium chloride)
• The names of many compounds with only two elements
often end in –ide.
– For example: MgO (magnesium oxide)
• If the name of compound end in –ate, they contain oxygen.
– For example: CaCO3 (Calcium Carbonate)
• Acids are compounds. Their names usually end in –ic acid.
– For example: HCl (Hidrochloric acid)

20. These are some of the chemical
formula
Compound Chemical Formula
Sodium Chloride NaCl
Magnesium Oxide MgO
Sodium hydroxide NaOH
Calcium carbonate CaCO3
Sulphuric acid H2SO4
Water H 2O
Ammonia NH3
Carbon dioxide CO2
Sucrose (sugar) C12H22O11

21. Chemical reaction between hydrogen and oxygen
producing water
N BEFORE REACTION AFTER REACTION
o Hydrogen Oxygen Water produced Excess
1 1 gram 8 gram 9 gram None
2 2 gram 16 gram 18 gram None
3 2 gram 8 gram 9 gram 1 gram of hydrogen
4 2 gram 17 gram 18 gram 1 gram of oxygen
5 3 gram 30 gram 27 gram 6 gram of oxygen
1. Calculate the comparison between the mass of
hydrogen and oxygen in water compound. What is
the result?
2. What will happen if the mass of hydrogen and
oxygen reacting does not follow the comparison?
3. What can you conclude about the comparison of
elements in the compound?

22. Conclusion
a. Water was compound by hydrogen
and oxygen with ratio of 1:8 (1 for
hydrogen and 8 for oxygen)
b. If the ratio of H:O was not equal to
1:8, there would be an excess
element (sisa)
c. The mass of elements before and
after a mass ratio of elements of a
“The
reaction was CONSTANT
compound component is constant”
(Perbandingan massa unsur-unsur penyusun senyawa
adalah tetap)

23. Think Time
1. When 4 grams of hydrogen react with 16
grams of oxygen, how many grams of water
are produced? If there is an excess,
determine the element and it mass
Answer:
• The comparison for the mass of
N
hydrogen and oxygen is 1:8
Before reaction After reaction
o Hydrogen Oxygen Water produced Excess
1 4 gram 16 gram 18 gram 2 gram of
(2 gram of hydrogen and 16 Hydrogen
gram of oxygen)

24. • In the world, there are many things that’s
not pure substances.
• Mixtures consist of two or more
substances that are not chemically joined
together.
• Mixtures can consist of elements,
compound or both. Also the substances
in a mixtures may be solids, liquids or
gaseswater is mixture of
Sea
compounds including water Brass is a mixture of the
and sodium chloride elements copper and zinc

25. Heterogeneou
Homogeneou s
s
The prefixes "homo"- indicate
sameness The prefixes: "hetero"- indicate
A homogeneous mixture has the difference.
same uniform appearance and A heterogeneous mixture consists
composition throughout. Many of visibly different substances or
homogeneous mixtures are phases. The three phases or states
commonly referred to as of matter are gas, liquid, and solid.
solutions.
In sugar
solution, sugar
is the solute
and water is
the solvent

26. Compound Mixtures
Composition Has a fixed composition Has a variable
by mass composition by mass
Melting and Has fixed melting and Has variable melting
Boiling point boiling points and boiling points
Properties Has it own properties Does not usually have
which are different from its own properties; it
its elements has the same
properties as its
component
Separation Cannot be separated by Can be easily
physical means. separated into its
Chemical reaction is components by
needed to separate the physical means.
elements

27. Identify each of the following diagrams as an atom, molecule, element,
compound or mixture.