Chapter 1 - Fundamental of Chemistry
part 1: Definition & Classification of Matter
Faculty of sciences
Department of materials science
Chemistry 1
Dr. Azeddine ADDOUN
Outline
Matter : definition and classification
Properties of matter
Substances and mixtures
Elements and compounds
Chemical formulas
Units of measurement
Summary
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Learning objectives
• To recognize the scope of chemistry.
• To classify matter
• To differentiate between physical and chemical properties
• To understand the type of change of matter
• To identify the basic units of measurement of the seven fundamental
properties
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Definition of Matter
• Matter, which is anything that occupies space and has mass
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Classification of matter
Under normal conditions, there are three distinct states of matter :
• Solids : relatively rigid and have fixed shapes and volumes.
• liquids : fixed volumes but assume the shape of their containers
• Gases : have neither fixed shapes nor fixed volumes and expand to
completely fill their containers
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Physical and chemical properties of matter
• A property is a distinguishing characteristic of a material used in its
identification.
• Generally, two types of properties of matter are recognized :
▶ physical property : material’s characteristic that can be observed
without changing the identity of the matter (color, solid, liquid, Mp ,
Bp ...)
• chemical property : material’s characteristic that describes the way
the matter undergoes change to form a different material (oxidation
of copper)
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Physical and chemical changes of matter
Like properties of matter, two categories of changes in matter are
recognized :
• A physical change : a process in which the
material changes its physical appearance
but not its chemical composition (ice cube
melting)
• A chemical change : is a process in which
a the material undergoes a change in
chemical composition and is turned into a
different material (gas burning).
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Physical change of matter
A Physical change is a process where the matter can change from one
physical state to another :
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Example 1.1
Complete each of the following statements by placing the word physical
or chemical change.
1. Fashioning of a piece of wood into a round table.
2. Straightening a bent piece of iron with a hammer.
3. Production of hydrogen gas by adding water to potassium.
4. Grating a piece of cheese.
5. Burning wood to make wood-fired pizzas
6. Photosynthesis of plants.
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Pure Substances
A pure substance is a single kind of matter :
• has a definite and constant composition
• has distinct properties.
• is identified by its appearance, smell and taste
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Mixtures
• A mixture is a combination of two or more substances
• Mixtures do not have constant composition and can be :
▶ homogeneous
▶ or heterogeneous
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Homogeneous and heterogeneous mixtures
Homogeneous mixture :
• the composition is the same throughout
the solution
• for example, dissolving a spoonful of sugar
in a glass of water
• separated by physical means : distillation,
crystallization, evaporation,
chromatography ....
Heterogeneous mixture :
• the composition of the mixture is not
uniform
• for example, adding a spoonful of sand in
a glass of water
• separated by physical means : filtration,
decantation, sieving, centrifugation ...
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Example 1.2
Classify each of the following as a heterogeneous mixture, a
homogeneous mixture, or a pure substance.
1. Water and coconut oil.
2. Salt water and sugar water.
3. Almond oil and olive oil.
4. Squeezed orange juice.
5. tablet of paracetamol.
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Elements
Element :
• is a pure substance that cannot be separated into simpler substances
• is represented using chemical symbols :
▶ one- or two-letter designation derived from the element’s name
▶ the first letter is always capitalized; while the second is not
• Currently, there are 118 known elements (88 elements occur
naturally)
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Natural abundance of elements
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Molecules
• A molecule is an aggregate of at least two atoms held together by
chemical forces.
• For example hydrogen gas, water and aspirin are all molecules made
up of two or more atoms.
• Molecules are classified into two categories: homoatomic and
heteroatomic.
▶ A homoatomic molecule is made up of the same kind of atoms (H2 ,
Cl2 , O2 ...), is element
▶ A heteroatomic molecule is made up of different kind of atoms
joined in a fixed ratio (H2 O, C6 H12 O6 , CO ...), is compound
• A molecule can be either
▶ diatomic such as H2 , CO, Cl2
▶ polyatomic such as CH4 , O3 , NH3
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Example 3
• Which of the following diagrams :
1. represent diatomic molecules ?
2. represent polyatomic molecules ?
3. represent molecules that represent an element ?
4. represent molecular compound ?
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Chemical formulas
• A chemical formula shows the atomic symbol of each element in a
compound accompanied by numerical subscripts to indicate the
number of each element present in a molecule.
▶ For example, oxygen gases and aspirin are respectively:
O2 , C9 H8 O4
▶ the chemical formula indicates that an oxygen molecule contains two
identical elements (2 O atoms) and aspirin molecule contains three
different elements (9 C, 8 H and 4 O atoms)
• The subscript numeral is written only if the number of atoms is > 1.
▶ For example, the molecular formulas of water and carbon dioxide are
respectively :
H2 O, CO2
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Summary of classification of matter
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Units of measurement
• Physical properties of matter are determined by measuring these
common quantities : mass, volume, length, time, temperature,
pressure, and concentration.
• A measured quantity is written as a number with an appropriate unit
according to the International System of Units.
• Other units (volume, density, energy ...) can be derived from these
base units:
▶ volume (L or mL) : cubic meter (m3 )
▶ density (g/mL) : kilogram per cubic meter (kg/m3 )
▶ concentration (mol/L) : liter per cubic meter (mol/m3 )
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Summary
• Matter is anything that occupies space and has mass.
• Matter can be classified according to physical and chemical
properties.
• Most matter consists of mixtures of pure substances, which can be
homogeneous or heterogeneous.
• Compounds can be broken down into elements by chemical reactions.
• Elements cannot be separated into simpler substances by chemical
means.
• The properties of substances can be classified as either physical or
chemical.
• Measured quantities are written using appropriate units according to
the SI base Units.
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End
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