Materials can change in different ways. Some changes can be reversed, and some cannot.
A physical change changes the shape, size, or state of a material, but no new material is made.
Examples:
ice melting,
paper folding,
A covalent bond is a chemical link of atoms that cooperate and share electron instead of giving it away.
Most atoms want a full outer shell (usually 8 electrons) to be stable. since some atoms aren't strong they have to come together so they can use the same electron the same time.
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Where we use it: gates, bridges, tools, cooking pansProperties:
Strong and hard
Magnetic (gets attracted to magnets)
Can rust when exposed to air and water
Metals are materials that are usually strong, shiny, and useful for making things.
Shiny (they have lustre)
Hard and strong
Good conductors of heat and electricity
An atom is the tiny particle that makes up all matter — everything you can see, touch, or even breathe!
Contains:
Protons (positive)
Properties:
Very hard
Heavy
Strong
Not flexible
Property MetalsNon-metals Appearance Usually shiny (lustrous) Usually dull Hardness Usually hard Usually soft or brittle Malleability Can be hammered into sheets Cannot be hammered; they break Ductility Can be drawn into wires Cannot be drawn into wires Conductivity Good conductors of heat and electricity Poor conductors of heat and electricity Sound Make a ringing sound when hit (sonorous) Do not make a ringing sound StateMostly solids (except mercury) Can be solid, liquid, or gas Examples Iron, copper, aluminium Oxygen, carbon, sulfur
Metals → shiny, strong, conduct electricity
Non-metals → dull, weak, do not conduct electricity
Many magnets are made from metals like iron, nickel, or cobalt.
These metals are called magnetic metals because magnets stick to them.
Metals usually have these extra properties too:
Conduct electricity → That’s why wires are made of metal.
Conduct heat → Metal spoons get hot in soup.
Magnetic (some metals) → Iron can stick to magnets.
Sonorous → Metals make a ringing sound when hit.
Solid – keeps its shape (like ice)
Liquid – flows and takes the shape of a container (like water)
Gas – spreads out and fills space (like water vapor)
When heated → particles move faster and spread apart.
Matter can change from one state to another when it gains or loses heat energy.
Solid
Liquid
Gas
Particle theory says that all matter is made up of tiny, tiny particles.
Matter means anything that has mass and takes up space — like air, water, your pencil, your desk… even YOU!
Here are the important ideas:
A state of matter tells us how particles (tiny pieces of matter) are arranged and how they move.
In a solid, particles are:
Packed very closely together
Definition:
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.
Easy way to remember:
Same element ➜ same protonsDifferent isotopes ➜ different neutrons
Example:
Carbon isotopes
What is the Periodic Table?
The Periodic Table is a chart that shows all the elements in the world, neatly arranged in a pattern.
Elements are basic substances that make everything around us(like oxygen, water, iron, gold).
How is the Periodic Table arranged?
Rows → called Periods
Columns → called Groups
States of Matter
Matter is anything that has mass and occupies space.Matter exists in different forms, called states of matter.
The main states of matter are:
Solid
Liquid
Gas
Experimental Techniques;
Experimental techniques are the methods scientists use to do experiments and learn about substances.
Examples:
Heating – to see how a substance changes
Cooling – to observe solid or liquid formation
Mixing – to check if substances react
organic chemistry is the study of substances that contain carbon.
What do organic compounds contain?
Carbon (C) – main element
Hydrogen (H)
Sometimes Oxygen (O), Nitrogen (N), Sulphur (S)
Examples of organic substances
Definition:
A chemical reaction is a process in which one or more substances change into new substances with different properties.
Main Points:
Substances before the reaction are called reactants.
Substances after the reaction are called products.
In a chemical reaction, new substances are formed.
Rocks
Types:
Igeous
sedimentar
Meta morphic
Made by:
Definition:
Brownian motion is the random zig-zag movement of very tiny particles when they are in a liquid or gas.
Why does it happen?
Tiny particles are hit from all sides by fast-moving molecules of the liquid or gas.
These hits are unequal, so the particle moves here and there.
Who discovered it?
A molecule is made when two or more atoms join together.
Simple molecules are made of only a few atoms.
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.
Hydrogen isotopes:
Protium (no neutron)
Deuterium (1 neutron)
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What happens when the number of electron change in an element?
What happens when the number of protons change in an element?
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.
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:
Physical quantities are things that we can measure.They tell us how big, how long, how heavy, or how hot something is.
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.
A rocket takes astronauts from Earth into space.
In space, there is no gravity, so you float.
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.
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!
A revolution in astronomy means a big change in how we understand space.
Long ago, people believed the Earth was the center of the universe.
Copernicus showed that the Sun is at the center — this was called the Heliocentric theory.
Galileo used a telescope to prove Copernicus was right.
The Moon is Earth’s natural satellite. It moves around Earth and shines by reflecting sunlight.
The Moon looks different on different days — these shapes are called phases.There are 8 main phases:
New Moon – The Moon is not visible.
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.
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.
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.
The starry sky is the dark night sky filled with shining stars.
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.
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.
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.
Thermal energy comes from moving particles inside everything.
More movement = more heat.
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.
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.
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.
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.
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.
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).
A push or pull.
Using force to move something away from you.
Using force to bring something towards you
A chart that shows Earth’s history from its beginning till now.
The biggest time unit.Example: Hadean, Archean, Proterozoic, Phanerozoic
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
Key words:
Colony life
Larvae
Pupae
Nest chambers
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 :
saltation
Erosion
Transportation
Wind erosion
Glacial
Key words :
Oxidation – Oxygen reacts with minerals and weakens the rock.
Hydrolysis – Water reacts with minerals and changes the rock into clay.
Carbonation – Carbon dioxide in rainwater forms a weak acid that dissolves rocks like limestone.
Abrasion – Rocks are worn down when they rub against other rocks.
Attrition – Rock pieces hit each other and become rounder and smaller.
Keywords:
Squeezed
Slate
Limestone
Marble
Granite
Key words:
Sediment
Layers
Pressure
Water
Cementation
Key words:
1. Magma
Lava
Crystals
Intrusive igneous rock
Key words:
Soil
Minerals
Organic matter
Fertile soil
Texture
Key words:
Rock
Igneous rock
Sedimentary rock
Metamorphic rock
Key words:
Acid
Base
Neutral
Neutralisation .
Salt
Key words:
pH
Indicator
pH scale
Strong Acid
Weak Acid
Acids are substances that taste sour and can be strong or mild.
Lemon juice
Tomato
Hard
Strong
Light in weight
Does not conduct heat or electricity
Metals: Shiny (lustrous)
Non-metals: Dull (not shiny)
Metals: Mostly solids (except Mercury, which is liquid)
Non-metals: Can be solid, liquid, or gas
Non-metals are elements that do NOT have the shiny, hard, and strong properties of metals.
They are almost the opposite of metals!
They do not shine like metals.Example: Carbon, sulfur.
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.
Shiny (Lustrous)Metals look shiny when polished.Example: Gold, silver.
Strong and HardThey do not break easily and can hold heavy weight.Example: Iron is used in buildings.
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.
Melting — Solid → LiquidHeat makes particles move faster and loosen up.Example: Ice becomes water.
Evaporation — boiling - Liquid → Gas/ Boiling More heat makes particles spread far apart.Example: Water becomes steam.
Freezing — Liquid → SolidCooling slows particles and locks them in place.Example: Water becomes ice.
Elements – They are pure substances made of only one kind of atom. Example: Oxygen (O), Hydrogen (H), Gold (Au).
Compounds –They are made when two or more elements combine chemically. Example: Water (H₂O) = Hydrogen + Oxygen,Salt (NaCl) = Sodium + Chlorine.
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.
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:
Homogeneous mixture – Looks the same everywhere (like sugar in water).
Taste – Sour in taste (like lemon, vinegar).
Touch – Corrosive, can burn or sting.
Litmus Test – Turns blue litmus paper red.
Reaction with Metals – Produces hydrogen gas.
pH Level – Less than 7.
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