Elements Compounds and Mixtures
Elements Compounds and Mixtures
Elements Compounds and Mixtures
MIXTURES
By Muhammad Ali
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Classification of
Matter
Matter is a
substance that
occupy space and
has mass.
Matter can be
classified into
i. Pure Matter
ii. Impure Matter
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Pure Substances and
Mixtures
If matter is not uniform throughout, then it is a heterogeneous mixture.
If matter is uniform throughout, it is homogeneous.
If homogeneous matter can be separated by physical means, then the
matter is a mixture.
If homogeneous matter cannot be separated by physical means, then the
matter is a pure substance.
If a pure substance can be decomposed into something else, then the
substance is a compound.
If a pure substance cannot be decomposed into something else, then the
substance is an element.
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CHARACTERISTICS OF PURE & IMPURE SUBSTANCES
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Elements
Element consist of unique type of atoms.
Element cannot be further broken into
simple substance by any chemical or
physical means.
There are 118 elements known.
Each element is given a unique chemical
symbol (one or two letters).
Elements are building blocks of matter.
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Elements
A sample of lead atoms (Pb). All
atoms in the sample consist of lead,
so the substance is homogeneous.
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Elements
The earths crust consists of 5 main elements.
The human body consists mostly of 3 main elements.
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Classification of Elements as Metals & Non-
Metals
S.No METALS NON- METALS
.
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ELEMENTS & SYMBOLS
METALS NON- METALS
S.No NAME SYMBOL PHYSICA NAME SYMBOL PHYSICAL
L STATE STATE
1 Aluminium Al Solid Argon Ar Gas
2 Calcium Ca Solid Bromine Br Liquid
3 Copper Cu Solid Carbon C Solid
4 Iron Fe Solid Chlorine Cl Gas
5 Magnesium Mg Solid Silicon Si Solid
6 Mercury Hg Liquid Sulphur S Solid
7 Potassium K Solid Hydrogen H Gas
8 Sodium Na Solid Iodine I Solid
9 Zinc Zn Solid Nitrogen N Gas
10 Gold Au Solid oxygen O Gas
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Compounds
Most elements react to form compounds.
Example, H2O
The proportions of elements in compounds are
the same irrespective of how the compound was
formed.
The composition of a pure compound is always
the same.
If water is decomposed, then there will always
be twice as much hydrogen gas formed as
oxygen gas.
.
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CHARACTERISTICS OF COMPOUND
It is a pure substance.
It is always homogenous
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CHARACTERISTICS OF COMPOUND
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Compounds
Lead has two charges listed, +2
and +4. This is a sample of lead
(II) chloride (PbCl2). Two or more
elements bonded in a whole-
number ratio is a COMPOUND.
This compound is formed from
the +4 version of lead. This is
lead (IV) chloride (PbCl4). Notice
how both samples of lead
compounds have consistent
composition throughout?
Compounds are homogeneous!
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Types of Compounds
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Molecular Compounds
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Network Solids
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EXAMPLES OF SOME FORMULA
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Mixtures
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Mixtures
A mixture of lead atoms and
chlorine atoms. They exist in no
particular ratio and are not
chemically combined with each
other. They can be separated by
physical means.
It is an impure substance
No formula
They can be mixed in any ratio.
The properties of the mixture are the properties of
its constituents.
Constituents can be easily seperated by physical
methods e.g. heating, drying, crystallization,
distillation etc.
It is either homogenous or heterogenous.
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DIFFERENCE BETWEEN COMPOUNDS & MIXTURES
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Physical vs. Chemical Properties
Physical properties can be measure without changing
the basic identity of the substance (e.g., color, density,
odor, melting point)
Chemical properties describe how substances react or
change to form different substances (e.g., hydrogen burns
in oxygen)
Intensive physical properties do not depend on how
much of the substance is present.
Examples: density, temperature, and melting point.
Extensive physical properties depend on the amount of
substance present.
Examples: mass, volume, pressure.
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Physical and Chemical Changes
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TESTING THE PURITY OF A SUBSTANCE
S.No TEST PURE IMPURE SUBSTANCE
SUBSTANCE
1 MELTING POINT It melts at a fix Do not have a fix melting
temperature e.g pure point. It melts at a range of
naphthalene melts at temperature. Impurity lower
80oC down the m.p. The greater
the % of impurity the lower
the m.p. e.g. impure
naphthalene melts at 76oC
to 78oC.
2 BOILING POINT It boils at fixed It boils at a range of
temperature e.g. pure temperature e.g. petrol
ethanol boils at 78oC boils at 35oC to 75oC.
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