Matter, Elements, Compounds
Complete SSC GD Syllabus Coverage
Introduction
Chemistry studies the composition, structure, properties, and changes of matter. SSC GD frequently asks questions from matter, states of matter, atoms, molecules, elements, mixtures, metals, non-metals, compounds, and basic chemistry laws.
This article fully covers all required topics.
1. Matter
Definition:
Anything that has mass and occupies space is called matter.
Examples:
2. States of Matter
Matter exists in three primary states:
Solid
- Fixed shape and volume
- Strong intermolecular forces
- Particles closely packed
Liquid
- No fixed shape, fixed volume
- Moderate intermolecular forces
- Particles can slide over each other
Gas
- No fixed shape or volume
- Weak intermolecular forces
- Particles move freely
Extra states (advanced):
Plasma and Bose–Einstein Condensate (Not much asked in SSC GD)
3. Properties of Matter
Diffusion
Mixing of particles of two substances.
Evaporation
Liquid changes to gas below boiling point.
Condensation
Gas converts to liquid.
Sublimation
Solid changes directly into gas.
Example: camphor, dry ice, naphthalene
Melting
Solid to liquid.
Boiling
Liquid to gas at its boiling point.
4. Atom and Molecule
Atom
Smallest unit of an element.
Molecule
Group of two or more atoms bonded together.
Examples: H₂, O₂, CO₂, H₂O
5. Element
Definition:
An element is a substance made up of only one type of atom.
Examples:
Key Facts:
- Total known elements: 118
- Periodic Table: classifies all elements
Types of Elements:
6. Metals and Non-Metals
Metals
Shiny, good conductors of heat and electricity, malleable, ductile.
Examples:
Iron, Copper, Aluminium, Gold
Non-metals
Poor conductors, dull, brittle.
Examples:
Carbon, Sulphur, Oxygen, Nitrogen
Metalloids
Show properties of both metals and non-metals
Examples:
Silicon, Boron, Arsenic
Exceptions:
- Mercury is a liquid metal
- Iodine is a lustrous non-metal
- Graphite conducts electricity
7. Compound
Definition:
A compound is formed when two or more elements combine chemically.
Examples:
Water
(H₂O)
Carbon dioxide
(CO₂)
Salt
(NaCl)
Sugar
(C₁₂H₂₂O₁₁)
Properties:
- Fixed ratio
- Cannot be separated by physical means
- New substance with new properties
8. Mixture
Definition:
A mixture contains two or more substances mixed physically.
Examples:
Types of Mixtures:
Homogeneous (uniform)
Examples: sugar solution, air
Heterogeneous (not uniform)
Examples: sand + water, oil + water
9. Difference Between Compounds and Mixtures
| Feature | Compound | Mixture |
|---|---|---|
| Formation | Chemical combination | Physical combination |
| Separation | Hard to separate | Easy to separate |
| Properties | New properties | Individual properties retained |
| Composition | Fixed ratio | Any ratio |
10. Physical and Chemical Changes
Physical Change
No new substance formed.
Examples:
- Melting of ice
- Boiling of water
- Breaking glass
Chemical Change
New substance is formed.
Examples:
- Burning paper
- Rusting of iron
- Digestion of food
11. Rusting of Iron
Rust formula:
Fe₂O₃.xH₂O
Conditions for rusting:
- Air (oxygen)
- Moisture (water)
Prevention:
- Painting
- Oiling
- Galvanization (zinc coating)
- Alloying
12. Alloys
Definition:
An alloy is a mixture of metals or metals with non-metals.
Examples:
Steel
= Iron + Carbon
Brass
= Copper + Zinc
Bronze
= Copper + Tin
Solder
= Lead + Tin
Key Point:
Alloys are stronger and more durable.
13. Solutions, Solvent, Solute
Solution
Homogeneous mixture.
Solute
Substance dissolved.
Example: salt
Solvent
Substance doing the dissolving.
Example: water
Important Fact:
Water is called the universal solvent.
14. Acids, Bases, Salts (Preview)
Acid
- Sour
- Turns blue litmus red
Base
- Bitter
- Slippery
- Turns red litmus blue
Salt
Formed from acid + base reaction
(Detailed article will follow next, but basic concepts)
SSC GD asks basic properties, examples, uses
15. Common Chemistry Terms Asked in SSC GD
- Melting point
- Boiling point
- Sublimation
- Evaporation
- Diffusion
- Alloy
- Rusting
- Solution
- Solvent
- Metals and non-metals
- Mixtures and compounds
- Physical vs chemical changes
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