1. ELEMENTS
The Simplest Matter

2. Elements Definition of Elements:
An element is a substance which cannot be split into two or more simpler substances by chemical reactions.
Every element is given a name and a chemical symbol.
For e.g. Sodium(Na), Magnesium(Mg), Carbon(C)
Oxygen gas (O2), etc

3. Abundance of Elements 109 have been discovered so far
92 elements occur naturally while the rest are man-made
Most elements are found combined with other elements in the form of ores or minerals
Some elements such as gold, sulphur, oxygen, nitrogen, neon, helium occur naturally in their free or uncombined state

4. For your interest … Find out the following:
(a)  What is the most abundant element in the       earth's crust?
(b)  What is the most abundant metal in the       earth's crust
(c)  What is the most abundant element in the       earth's atmosphere?

5. Classification of Elements –
Periodic Table
The elements have been classified according to their chemical properties into a chart called the Periodic Table as shown below.

6. In the periodic table… In the periodic table,
Each vertical column is called a group.
Elements in a group have similar chemical properties. Each group has its own unique properties.
Each horizontal row is called a period.
Elements in a period from left to right show a gradual change from metallic properties to non-metallic properties.

7. In the periodic table… In the periodic table,
Each element is represented by chemical symbol.
Chemical Name
Chemical Symbol
Aluminium Al
Zinc Zn
Copper Cu
Magnesium Mg
Mercury Hg
Note: Shown on this slide are common elements you need to know.

8. In the periodic table… Chemical Name Chemical Symbol Iron Fe Carbon C
Sulfur S
Chlorine Cl
Nitrogen N
Iodine I
Hydrogen H
Oxygen O
Note the spelling of “sulfur”. No longer “sulphur”.
By extension,
Sulfate, sulfide,
Sulfuric acid.
Note: Shown on this slide are common elements you need to know.

9. Classification of Elements
Elements can be classified into :
Metals
e.g. aluminium, calcium, copper, mercury, iron, zinc
Non-metals
e.g. oxygen, hydrogen, helium, iodine, sulphur

10. Non-metallic elements
Physical Properties of Metallic & Non-metallic Elements
Metallic element
Non-metallic elements
High melting and boiling points (exists as solids at room temperature except for mercury which exists as a liquid)
Low melting and boiling points (exists as solids, liquids or gases at room temperature)

11. Non-metallic elements
Physical Properties of Metallic & Non-metallic Elements
Metallic element
Non-metallic elements
Good heat conductors
Poor heat conductors
Good electrical conductors
Poor electrical conductors
(except for graphite)

12. Non-metallic elements
Physical Properties of Metallic & Non-metallic Elements
Metallic element
Non-metallic elements
Ductile
(can be drawn into wires)
Non-ductile or snap easily (cannot be drawn into wires)
Malleable
(can be beaten into shapes without breaking)
Brittle
(easily broken when beaten)

13. Non-metallic elements
Physical Properties of Metallic & Non-metallic Elements
Metallic element
Non-metallic elements
Shiny
(lustrous)
Dull in appearance (not lustrous)
High densities
Low densities
Sonorous
(produce a ringing sound when hit)
Not sonorous

14. Uses of some elements
Sulfur

15. Uses of some non-metallic elements
Carbon exists in several different forms (called allotropes) -diamond, graphite, soot, charcoal
Diamond is the hardest natural substance.
Thousands of tiny diamonds are attached to saws and drills for cutting concrete and drilling into rocks.
Uses: pencil leads, fuel, constitutes living tissues

16. Uses of some non-metallic elements
This gas is an unreactive element. It does not combine readily with other elements. Hence it can be used in the packing of food
It is also used in the making of fertilisers.
Uses: fertilisers, freezing agent for food, constitutes plants and animal proteins

17. Uses of some non-metallic elements
Sulfur is a yellow non-metallic element, found in the free state.
It is used to harden rubber used for making tyres.
It is also used in the manufacture of sulfuric acid, pesticides and drugs.
Uses: drugs, fireworks, to harden rubber, insecticides, medicinal drugs

18. Uses of some non-metallic elements
Iodine is a non-metallic element that sublimes when heated to form a violet vapour.
When dissolved in ethanol, it forms tincture of iodine, used as an antiseptic.
Uses: antiseptic

19. Uses of some non-metallic elements
Oxygen is the most important gaseous element to all living organisms on earth
They need it for respiration.
Uses: combustion, respiration

20. Uses of some non-metallic elements Name of non-metallic element
Chlorine
Bleaching powder, kills bacteria, used in making plastics (PVC)
Fluorine
Prevents tooth decay
Silicon
Transistors, manufacture of steel

21. Uses of some metallic elements
Zinc is used to coat iron sheets to make galvanised iron.
It is also mixed with copper to form the alloy, brass.
Uses: roofs, dry cell casings

22. Uses of some metallic elements
Mercury is the only metallic element that is a liquid at room temperature.
It is used in liquid-in-glass thermometers, fluorescent lamps and some dental fillings
Uses: fluorescent lamps, thermometers

23. Uses of some metallic elements
Magnesium burns with a white dazzling light and so it is used in distress flares.
It is also used in making fireworks.
Uses: fireworks

24. Uses of some metallic elements
Aluminium, being strong, and of low density is used to make aeroplane parts.
This metal is also used to make drink cans, cooking utensils and ladders.
Being a good electrical conductor and of low density, it is also used to make overhead electricity cables.
Uses: pots and pans, foil wraps, window and door frames, light alloy

25. Uses of some metallic elements
This metal is commonly used to make electrical wires as it is a good electrical conductor and is inexpensive.
It is also used to make water pipes.
When mixed with tin, it forms the alloy called bronze and when mixed with zinc, it forms the alloy called brass.
Uses: electrical wires and switches, coins, water pipes, tanks

26. Uses of some metallic elements Name of metallic element
Calcium
For the body to grow strong teeth and bones
Iron
Manufacture of steel, railings, grills, cooking utensils
Lead
Lead shots, accumulators