GRADE 8 RATIONALIZED INTEGRATED SCIENCE
LESSON NOTES COMPLETE
STRAND 1- MIXTURES, ELEMENTS AND COMPOUNDS.
ELEMENTS AND COMPUNDS
Meaning of Atoms, Elements, molecules and Compounds.
Matter is anything that occupies space and has mass.
Matter is composed of pure substances and mixtures.
The pure substances are can be element and compounds while the mixtures can either be uniform or non-
uniform.
An element is a substance that cannot be decomposed into simpler substances by chemical or physical
means.
An element is a pure substance which cannot be made simpler using chemical means.
Elements are the building blocks of matter. Everything around is made up of an element or elements.
An element is made of atoms.
Atoms of the same element are identical.
A compound is pure substance that consists of atoms of two or more elements that are chemically joined
together.
Compounds are formed when atoms of different elements react.
Compounds can be broken down into elements through chemical reactions.
Sodium and chlorine are elements that combine chemically to form sodium chloride which is a
compound.
Relating common elements to their symbols.
Pure substances either elements or compounds has a unique name and symbol.
A symbol is a sort -hand notation for the chemical name of an element.
Chemical symbols are used instead of names by scientists because they are much easier, convenient and
universally recognized.
Compounds are represented by a chemical formula.
A chemical symbol is usually derived from first letter of the English name of the element. It is also
derived from Latin name of the element.
,For example,
H is the chemical symbol of hydrogen.
O is the chemical symbol of Oxygen.
K is the chemical symbol of potassium. For potassium the K is derived from Latin word Kalium.
Some elements might start with same first letters, such as Carbon, Calcium, Chlorine and Copper
have their names starting with letter C, therefore letter C can not be used to represent all of them as chemical
symbol.
The first letter C is assigned to represent Carbon, while the rest of the elements are assigned two letters
from their name as follows.
✓ Carbon represented by C.
✓ Calcium represented by Ca.
✓ Chlorine represented by Cl
✓ Copper represented by Cu from Latin word cuprum
The first letter of a symbol is always capitalized, while the second letter is written in small letters.
The symbols of some elements derived from English names are as follows:
Name of Chemical symbol Name of element Chemical symbol
element
1 Hydrogen H Nitrogen N
2 Helium He 8 Oxygen O
3 Lithium Li 9 Fluorine F
4 Beryllium Be 10 Neon Ne
5 Boron B 11 Magnesium Mg
6 Carbon C 12 Aluminium Al
The symbols of some elements derived from Latin names are as follows:
Name of Latin name. Chemical Name of Latin name Chemical
element symbol element symbol
, 1 Sodium Natrium Na Silver Argentum Ag
2 Iron Ferrum Fe 8 Tin Stannum Sn
3 Copper Cuprum Cu 9 Zinc Zincum Zn
4 Lead Plumbum Pb
5 Gold Aurum Au
6 Mercury hydrargyrum Hg
Compounds are combinations of two or more elements.
A chemical formula is an expression that shows the elements in a compound and the relative proportions
of those elements.
Water is composed of Hydrogen and Oxygen in the ration 2:1.
The chemical formula of water is H2O.
Sodium chloride also called common salt is composed of Sodium and Chlorine in the ration 1:1. The
chemical formula for Sodium chloride is NaCl.
Application of common elements in our day-to-day life.
Food nutrients are chemical compounds found in foods. These nutrients are used by the body to function
properly and maintain health.
Examples of food nutrients include:
Proteins.
Fats.
Carbohydrates.
Vitamins.
Mineral salts.
Food nutrients are made up o various elements such as: carbon, hydrogen, oxygen and nitrogen.
Various food sources that contain various elements.
Mineral element of Examples of food sources
compound
Carbon present in all foods
Nitrogen Meat, chicken, fish, milk and eggs.
, Flouride Fish, potatoes, spinach and black tea.
Calcium Milk, cheese, green leafy vegetables, soya beans, bread and fish
Copper Nuts and shellfish.
Iron Liver, meat, beans, nuts and whole grain.
Magnesium Spinach, bread, fish, meat and dairy foods.
Phosphorus Read meat, dairy foods, fish, bread and rice.
Potassium Banana, vegetables, milk, fish, beef, chicken and bread.
Sodium chloride Salt is found naturally at low levels in all foods.
Some salt is added to processed foods and meat products.
Plants receive water, mineral and other nutrients from the soil which are carried to the other parts of the
plant
There are various mineral elements present in the soil that are absorbed by the roots of plants.
The following are some of the important mineral elements required by plants:
Phosphorus & magnesium – they are essential for the growth, development and reproduction of the
plant.
Potassium – increases the quality of fruits and vegetables.
Various elements are used in manufacture of different toiletries that we use in day-to-day life.
Some toiletries, for example toothpaste contains flouride compounds to prevent tooth decay while soaps and
detergents contain a compound of potassium.
Importance of various elements and compounds.
Gold:
Gold is a precious metal.
It is widely used to make jewellery as it is fairly soft and easy to work with.
It is attractive in appearance and neither rust or discolours.
Silver:
It is a precious metal.
It is used in making jewellery but it tends to discolour.
It is also used in making cutlery, teapots and medals.
Iron:
It is one of the most useful metals.
It is strong, can be sharpened and it is easy to work with.
LESSON NOTES COMPLETE
STRAND 1- MIXTURES, ELEMENTS AND COMPOUNDS.
ELEMENTS AND COMPUNDS
Meaning of Atoms, Elements, molecules and Compounds.
Matter is anything that occupies space and has mass.
Matter is composed of pure substances and mixtures.
The pure substances are can be element and compounds while the mixtures can either be uniform or non-
uniform.
An element is a substance that cannot be decomposed into simpler substances by chemical or physical
means.
An element is a pure substance which cannot be made simpler using chemical means.
Elements are the building blocks of matter. Everything around is made up of an element or elements.
An element is made of atoms.
Atoms of the same element are identical.
A compound is pure substance that consists of atoms of two or more elements that are chemically joined
together.
Compounds are formed when atoms of different elements react.
Compounds can be broken down into elements through chemical reactions.
Sodium and chlorine are elements that combine chemically to form sodium chloride which is a
compound.
Relating common elements to their symbols.
Pure substances either elements or compounds has a unique name and symbol.
A symbol is a sort -hand notation for the chemical name of an element.
Chemical symbols are used instead of names by scientists because they are much easier, convenient and
universally recognized.
Compounds are represented by a chemical formula.
A chemical symbol is usually derived from first letter of the English name of the element. It is also
derived from Latin name of the element.
,For example,
H is the chemical symbol of hydrogen.
O is the chemical symbol of Oxygen.
K is the chemical symbol of potassium. For potassium the K is derived from Latin word Kalium.
Some elements might start with same first letters, such as Carbon, Calcium, Chlorine and Copper
have their names starting with letter C, therefore letter C can not be used to represent all of them as chemical
symbol.
The first letter C is assigned to represent Carbon, while the rest of the elements are assigned two letters
from their name as follows.
✓ Carbon represented by C.
✓ Calcium represented by Ca.
✓ Chlorine represented by Cl
✓ Copper represented by Cu from Latin word cuprum
The first letter of a symbol is always capitalized, while the second letter is written in small letters.
The symbols of some elements derived from English names are as follows:
Name of Chemical symbol Name of element Chemical symbol
element
1 Hydrogen H Nitrogen N
2 Helium He 8 Oxygen O
3 Lithium Li 9 Fluorine F
4 Beryllium Be 10 Neon Ne
5 Boron B 11 Magnesium Mg
6 Carbon C 12 Aluminium Al
The symbols of some elements derived from Latin names are as follows:
Name of Latin name. Chemical Name of Latin name Chemical
element symbol element symbol
, 1 Sodium Natrium Na Silver Argentum Ag
2 Iron Ferrum Fe 8 Tin Stannum Sn
3 Copper Cuprum Cu 9 Zinc Zincum Zn
4 Lead Plumbum Pb
5 Gold Aurum Au
6 Mercury hydrargyrum Hg
Compounds are combinations of two or more elements.
A chemical formula is an expression that shows the elements in a compound and the relative proportions
of those elements.
Water is composed of Hydrogen and Oxygen in the ration 2:1.
The chemical formula of water is H2O.
Sodium chloride also called common salt is composed of Sodium and Chlorine in the ration 1:1. The
chemical formula for Sodium chloride is NaCl.
Application of common elements in our day-to-day life.
Food nutrients are chemical compounds found in foods. These nutrients are used by the body to function
properly and maintain health.
Examples of food nutrients include:
Proteins.
Fats.
Carbohydrates.
Vitamins.
Mineral salts.
Food nutrients are made up o various elements such as: carbon, hydrogen, oxygen and nitrogen.
Various food sources that contain various elements.
Mineral element of Examples of food sources
compound
Carbon present in all foods
Nitrogen Meat, chicken, fish, milk and eggs.
, Flouride Fish, potatoes, spinach and black tea.
Calcium Milk, cheese, green leafy vegetables, soya beans, bread and fish
Copper Nuts and shellfish.
Iron Liver, meat, beans, nuts and whole grain.
Magnesium Spinach, bread, fish, meat and dairy foods.
Phosphorus Read meat, dairy foods, fish, bread and rice.
Potassium Banana, vegetables, milk, fish, beef, chicken and bread.
Sodium chloride Salt is found naturally at low levels in all foods.
Some salt is added to processed foods and meat products.
Plants receive water, mineral and other nutrients from the soil which are carried to the other parts of the
plant
There are various mineral elements present in the soil that are absorbed by the roots of plants.
The following are some of the important mineral elements required by plants:
Phosphorus & magnesium – they are essential for the growth, development and reproduction of the
plant.
Potassium – increases the quality of fruits and vegetables.
Various elements are used in manufacture of different toiletries that we use in day-to-day life.
Some toiletries, for example toothpaste contains flouride compounds to prevent tooth decay while soaps and
detergents contain a compound of potassium.
Importance of various elements and compounds.
Gold:
Gold is a precious metal.
It is widely used to make jewellery as it is fairly soft and easy to work with.
It is attractive in appearance and neither rust or discolours.
Silver:
It is a precious metal.
It is used in making jewellery but it tends to discolour.
It is also used in making cutlery, teapots and medals.
Iron:
It is one of the most useful metals.
It is strong, can be sharpened and it is easy to work with.
