Simple Molecules:

A molecule is made when two or more atoms join together.

Simple molecules are made of only a few atoms.

Examples:

• Hydrogen (H₂) – two hydrogen atoms

• Oxygen (O₂) – two oxygen atoms

Definition :

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.

Examples

• Hydrogen isotopes:

  • Protium (no neutron)

  • Deuterium (1 neutron)

Definition:

The periodic table is a chart that shows all the elements in science, arranged in a special order.

How the periodic table is arranged:

• Rows are called Periods ➝ There are 7 periods.

• Columns are called Groups ➝ There are 18 groups.

• Elements in the same group have similar properties.

  
  

1. Elements

Definition: An element is a pure substance made of only one kind of atom.

Examples:

• Oxygen (O) – we breathe it

• Iron (Fe) – used to make tools

• Gold (Au) – used in jewellery

Definition:

What are Physical Quantities?

Physical quantities are things that we can measure.They tell us how big, how long, how heavy, or how hot something is.

Examples of Physical Quantities:

• Length – how long something is

• Mass – how heavy something is

Definition :

A journey into space is traveling beyond Earth to explore the stars, planets, and the vast universe.

Main Points:

1. A rocket takes astronauts from Earth into space.

2. In space, there is no gravity, so you float.

3. Space is dark, silent, and filled with stars and planets.

Definition:

400 years of astronomy means how our study of space has grown from Galileo’s first telescope to today’s modern space discoveries.

Main Points:

• Galileo started modern astronomy 400 years ago.

• Telescopes became better and better.

• Humans went to space.

A revolution in astronomy is when new discoveries completely change our knowledge about space and the universe!

Main Points:

1. A revolution in astronomy means a big change in how we understand space.

2. Long ago, people believed the Earth was the center of the universe.

3. Copernicus showed that the Sun is at the center — this was called the Heliocentric theory.

4. Galileo used a telescope to prove Copernicus was right.

Definition:

The Moon is Earth’s natural satellite. It moves around Earth and shines by reflecting sunlight.

Phases of the Moon:

The Moon looks different on different days — these shapes are called phases.There are 8 main phases:

1. New Moon – The Moon is not visible.

2. Waxing Crescent – A small curved light appears.

Definition:

Seeing stars and planets means looking at bright objects in the night sky that shine from far away in space.

Interesting Points:

• Stars are huge balls of hot glowing gas.

• Planets do not make their own light — they only reflect the Sun’s light.

• Some planets, like Venus, look like very bright stars.

Definition:

Planets are big round objects in space that keep moving around the Sun in fixed paths.

Main Points:

• All planets move—they never stay still.

• They move around the Sun in orbits (special paths like loops).

• They also spin on their own axis like a top.

Definition:

The starry sky is the dark night sky filled with shining stars.

INTERESTING POINTS:

• Stars look tiny, but they are actually HUGE burning balls of gas.

• We can see only a small number of stars with our eyes; the rest are too far away.

• Some stars are bigger than our Sun, and some are smaller.

Definition:

Day and night happen because the Earth spins  on its axis.

Main Points:

• Earth spins like a top.

• It takes 24 hours to make one full spin.

• When your side faces the Sun → it is day.

Definition:

Kinetic energy is the energy of movement.Anything that is moving — even a tiny ant — has kinetic energy.

Main Points:

• If something moves, it has kinetic energy.

• The faster it moves, the more kinetic energy it gets.

• Heavier things have more kinetic energy when they move.

Definition:

Thermal energy is Heat . It is the energy that makes things warm or hot.The tiniest particles in everything move — when they move faster, the thing gets hotter.When they move slowly, it gets cold.

Main Points:

1. Thermal energy comes from moving particles inside everything.

2. More movement = more heat.

3. Less movement = less heat.

Definition:

A type of energy stored inside the bonds of chemicals. When the bonds break in a reaction, the energy is released.

Main Points:

• Chemical stores of energy are places where energy is kept inside chemicals.

• They are found in food, fuels, and batteries.

• Energy is released when a chemical reaction happens (like burning fuel or digesting food).

Using energy means taking energy from a source (like the Sun, electricity, or food) and using it to do work, move things, or make something happen.

Interesting Points

• Energy is never lost; it only changes form (like electrical → light).

• Your body is like a machine that runs on food energy.

• Even when you sit quietly, your body still uses energy to breathe and think.

• Plants use sunlight energy to make their own food.

Definition:

A pattern of falling means the way something falls again and again in the same style or order.

Interesting points:

• Things fall because gravity pulls everything down.

• The shape of an object changes the pattern of falling (flat paper vs crumpled paper).

• Air resistance slows down light objects and makes them fall in zig-zag or wavy patterns.

Definition:

Air resistance is a force that slows things down when they move through air.

Ev.

Main Points

• Air resistance is a type of friction.

• It always acts in the opposite direction of movement.

Definition:

A magnet is an object that can pull certain metals towards It . It has a special invisible force called magnetic force.

Main Points

• A magnet has two poles: North pole (N) and South pole (S).

• Opposite poles attract (N + S).

• Same poles repel (N + N or S + S).

Definition :

Friction is a force that tries to stop things from sliding or moving.

Main Points

• Friction happens when two surfaces touch.

• It always acts in the opposite direction of movement.

• Rough surfaces create more friction.

Definition:

Weight is the force with which gravity pulls an object towards the center of the Earth (or any other celestial body).

Interesting points:

• Your weight changes if you go to the Moon, Mars, or any other planet, because gravity is different there.

• Your mass stays the same everywhere, even if your weight changes.

• Weight is a force, so it has both size and direction (downwards toward the center of the planet).

Force

A push or pull.

Push

Using force to move something away from you.

Pull

Using force to bring something towards you

Geological Time Scale (GTS)

A chart that shows Earth’s history from its beginning till now.

2. Eon

The biggest time unit.Example: Hadean, Archean, Proterozoic, Phanerozoic

3. Era

Large divisions inside an eon.Example: Paleozoic, Mesozoic, Cenozoic

• 4.5 billion years – Earth’s age

• Formation – how Earth was made

• Dust and gas cloud – where Earth began

• Accretion – small pieces joining to form Earth

• Solar system – Sun + planets

• Radiometric dating – method to find age

Keywords:

1. Insects

2. Colony

3. Queen

4. Workers

5. Soldiers

Key words:

1. Colony life

2. Larvae

3. Pupae

4. Nest chambers

5. Soil tunnels

Definition:

Soil erosion is the process where the top layer of soil is detached, transported, and deposited in another location by natural forces like wind and water, or by human activity. It is a form of land degradation that can be a slow, natural process or an accelerated problem caused by agriculture or other human activities. 

Main cause:

Soil erosion is caused by natural forces like water and wind, and by human activities such as deforestation, intensive agriculture, and overgrazing. These factors work by removing protective vegetation, disturbing the soil structure, or directly moving soil particles through rain, floods, or strong winds. 

Main points:

• Definition: Soil erosion is the wearing away and transportation of the fertile, upper layer of soil (topsoil).

  
  

Key words :

1. Fossil

2. Bone

3. Shell

4. Print

5. Trace

Key words :

1. saltation

2. Erosion

3. Transportation

4. Wind erosion

5. Glacial

Key words :

1. Oxidation – Oxygen reacts with minerals and weakens the rock.

2. Hydrolysis – Water reacts with minerals and changes the rock into clay.

3. Carbonation – Carbon dioxide in rainwater forms a weak acid that dissolves rocks like limestone.

4. Abrasion – Rocks are worn down when they rub against other rocks.

5. Attrition – Rock pieces hit each other and become rounder and smaller.

Keywords:

1. Squeezed

2. Slate

3. Limestone

4. Marble

5. Granite

Key words:

1. Sediment 

2. Layers

3. Pressure

4. Water 

5. Cementation

Key words:

1. Magma 

2. Lava 

   
   

3. Crystals

    

4. Intrusive igneous rock 

   
   

Key words:

1. Soil 

   
   

2. Minerals 

   
   

3. Organic matter 

   
   

4. Fertile soil 

   
   

5. Texture 

   
   

Key words:

Rocks

• Rock

• Igneous rock

• Sedimentary rock

• Metamorphic rock

Key words:

1. Acid

2. Base

3. Neutral 

4. Neutralisation .

5. Salt 

Key words:

pH

Indicator

pH scale

Strong Acid

Weak Acid

ACIDS

What are acids?

Acids are substances that taste sour and can be strong or mild.

Examples in everyday life:

• Lemon juice

• Tomato

Wood

Properties:

• Hard

• Strong

• Light in weight

• Does not conduct heat or electricity

 Appearance

• Metals: Shiny (lustrous)

• Non-metals: Dull (not shiny)

  
  

2. State

• Metals: Mostly solids (except Mercury, which is liquid)

• Non-metals: Can be solid, liquid, or gas

  
  

What are Non-Metals?

Non-metals are elements that do NOT have the shiny, hard, and strong properties of metals.

They are almost the opposite of metals!

Properties of Non-Metals

1. They are dull

They do not shine like metals.Example: Carbon, sulfur.

Metal

Metals are materials found in the earth that are usually solid, strong, and shiny.They have special properties that make them very useful in our daily life.

Properties of Metals

1. Shiny (Lustrous)Metals look shiny when polished.Example: Gold, silver.

2. Strong and HardThey do not break easily and can hold heavy weight.Example: Iron is used in buildings.

3. Good Conductors of Electricity.

Changing states means a substance can change its form when heat is added or removed.Its particles move differently in each state, so when temperature changes, the state also changes.

When Heat Is Added

1. Melting — Solid → LiquidHeat makes particles move faster and loosen up.Example: Ice becomes water.

2. Evaporation — boiling - Liquid → Gas/ Boiling More heat makes particles spread far apart.Example: Water becomes steam.

When Heat Is Removed

3. Freezing — Liquid → SolidCooling slows particles and locks them in place.Example: Water becomes ice.

1. Elements – They are pure substances made of only one kind of atom. Example: Oxygen (O), Hydrogen (H), Gold (Au).

2. Compounds –They are made when two or more elements combine chemically. Example: Water (H₂O) = Hydrogen + Oxygen,Salt (NaCl) = Sodium + Chlorine.

3. Mixtures – They are made when two or more substances are mixed but not chemically joined. Example: Air (a mix of gases), Salad, Fruit juice.

Easy way to remember:

• Element – Only one type.

• Compound – Joined together.

1. Simple molecules:Simple molecules are small groups of atoms joined together. Example:

• Water (H₂O) – has 2 hydrogen atoms and 1 oxygen atom.

• Oxygen (O₂) – has 2 oxygen atoms.

• Carbon dioxide (CO₂) – has 1 carbon and 2 oxygen atoms.

They are called simple because they have only a few atoms and are not very big.

2. Covalent bonds:A covalent bond is when atoms share electrons to stay together.

Atoms: The smallest parts of matter.

Atomic structure:

• Nucleus in the center (has protons and neutrons).

• Electrons move around the nucleus.

Example: Water is made of atoms of hydrogen and oxygen.

1. Mixes (Mixtures)

   • A mixture is when two or more things are put together but they don’t change into something new.

   • Example: Sand + salt, rice + dal, nuts + raisins.

   • You can separate them easily.

   Types of mixtures:

   1. Homogeneous mixture – Looks the same everywhere (like sugar in water).

   
   

🧪 Properties of Acids:

1. Taste – Sour in taste (like lemon, vinegar).

2. Touch – Corrosive, can burn or sting.

3. Litmus Test – Turns blue litmus paper red.

4. Reaction with Metals – Produces hydrogen gas.

5. pH Level – Less than 7.