The document discusses different types of materials. It defines materials as substances that things are made of, which can be natural or human-made. There are over 300,000 known materials today. Materials are made up of atoms, which combine to form solids, liquids or gases. Atoms contain protons, neutrons and electrons. Materials like metals bond through shared electrons, while other materials involve electron transfers between atoms. Common materials include wood, glass, metals and polymers. Metals are good conductors due to delocalized electrons. The document also discusses carbon-based materials like diamond and graphite, as well as iron, steel, and how carbon chains form the basis of living things and oil.

1. Materials
 The main substance from which all the things
are made of, is called material.
 Materials can be natural: like wood, cotton or
human made: like plastic.
 There are more than 3,00,000 types of
materials available today, and the no. is still
increasing as scientist are creating new
materials.
 Main categories of materials are: wood, glass,
metals, semiconductors, ceramic, polymers
etc.

2. What are materials made of?
All materials whether
they are
Solid, like steel
or Liquid, like tea
or Gaseous, like air
are made up of atoms!

3. Atoms are what give materials their properties:
Mass (kg) is to do with the number of atoms in a given volume
Strength is to do with how well atoms stick together
Corrosion (rust) is to do with atoms reacting with each other

4. Atoms are made up of Protons,
Neutrons and Electrons.
At the centre of an atom
(Nucleus), there will be Protons
and Neutrons; Electrons move
around the nucleus.
- Protons carry positive charge,
Electrons carry negative charge
+ and Neutrons are neutral.
+ +
- Atoms overall are neutral
Protons = Electrons
-

5. Periodic Table
Non-Metals
Soft Metals
Metals

6. Atoms stick together to make materials.
How they stick together depends on what the
electrons do
Lots of metal Different atoms stick
atoms share One kind of atom together, then these
their electrons gives electrons to groups stick together
another kind of atom

7.  Metal atoms stick together because the negative electrons
attract the positive ions
 Metals have high melting points because these attractions are
very strong
 Metals fuse with other metals to form “alloys”.
 All metals are solids at ordinary temperatures except Mercury.
 Most of the metals are found in combined form usually mixed
with other elements and earthy materials.
 Metals conduct electricity because electrons can flow through
the structure - this is in fact what electricity is!

8. Facts about Iron and Steel
Iron is available in nature in the form of minerals.
These minerals are combination of iron, oxygen and sulfur.
Iron is obtained from these minerals by following process:
Minerals (iron + oxygen) + (Carbon) = iron + (Carbon + oxygen)
Iron is an element, a pure substance which can rust on exposure to
water and air.
Steel is an alloy (a mixture) comprising of iron and carbon.
Properties of iron and steel are different.
Steel may not be as strong as iron is but it is more resistant and
does not corrode and gets rusted like iron does. So steel is used for
industrial purpose more than iron.
The iron that contains less than 2% of carbon is called steel
whereas which contain more than 2% of carbon is known as pig iron.

9. Iron and Steel
CO2
Coke
carbon
Iron Ore
Cast
iron Iron
oxygen

10. Types of iron
Mild Steel Stainless Steel
Cast Iron
chromium
nickel
Medium Carbon
Steel
High Carbon
Steel

11. Mild Steel: Contains 0-0.3% carbon
Easy to shape
Tough
Most common and cheapest steel
Best metal to weld
Medium Carbon Steel:Contains 0.3-0.8% carbon
More difficult to shape
More brittle
Harder and stronger than mild steel
High Carbon Steel: Contains 0.8-2% carbon
Very difficult to shape
Most brittle
Hardest and strongest steel
Stainless Steel: Iron with carbon, chromium and nickel atoms
Stainless steel does not rust
Because of its antibacterial properties, used in
food transport/preparation and surgical equipment
Comes in different grades of hardness Vs ductility
depending on application
More expensive

12. Carbon
Diamond and graphite are examples of pure carbon. Both have
different characteristics.
Diamond is immensely strong. It is used for cutting strong material.
Graphite is very soft (think of pencil). It is a good conductor of
electricity. It is also used as a lubricant.
Diamond Graphite

13. Carbon - oil
Carbon forms chains which many different atoms can join to. All living matter,
plants, animals, even human beings are based around carbon chains. When
living things die, they return to the earth. In some areas, over thousands of
years, this material gets buried deep underground and heated and pressed.
And then turns into oil.
Oil is a finite
resource. But our
demand for it is
never ending. Oil is
getting expensive
because it is
extracted from
difficult and less
accessible places.

14. We will study about other materials
like Copper, Aluminium, Wood etc. in
the next presentation :
„Materials – Part II‟.