Ridha Fathima

Chemical reaction

• Endothermic reactions are chemical reactions that absorb energy instead of releasing it.

• This energy is usually taken as heat, but can also be light or electrical energy in rare cases.

• Because energy goes inward, the products have more energy than the reactants.

• These reactions often feel cold because the energy is being pulled from the surroundings.

2. Reactants

1. Chemical Reaction

• Exothermic reactions are a type of chemical reaction.

• Bonds break in reactants and new bonds form in products.

• More energy is released than absorbed, creating heat.

• Heat, light, or sound may appear because of this energy release.

2. Reactants

(Oxidation Explained Simply)

1. What Are Materials?

Materials are the substances around us — metals, non-metals, fuels, food, wood, plastic, fabrics, etc.

Different materials react with oxygen in different ways.

2. What Does “Reacting With Oxygen” Mean?

1. Presence of Fuel

Burning begins only if something that can burn is present.Examples: paper, wood, kerosene, LPG.

2. Oxygen from Air

The fuel must have oxygen around it.Without oxygen, no burning can start.

3. Heating the Fuel

The fuel must be heated to its ignition temperature.This is the minimum temperature at which the fuel starts burning.

Atomic Structure

Atomic structure means how an atom is built inside.

Every atom has a nucleus in the centre and electrons moving around it.

Inside the nucleus are protons (positively charged) and neutrons (no charge).

The electrons move around the nucleus in specific paths called shells or orbits.

So the atomic structure shows how protons, neutrons, and electrons are arranged inside an atom.

🔹 What is an Atom?An atom is the smallest particle of an element that still has the same properties as that element. Everything around us—air, water, plants, animals, and even you—is made up of atoms.

🔹 Main Parts of an AtomAn atom is made up of three main subatomic particles:

Protons (⁺)Found in the nucleus (center) of the atom.Have a positive charge.The number of protons = atomic number (this tells which element it is).

Neutrons (0)Also found in the nucleus.Have no charge (they are neutral).They add mass to the atom and help keep the nucleus stable.

Electrons (⁻)Move around the nucleus in regions called energy levels or shells.Have a negative charge.They are very light compared to protons and neutrons.

🔹 Structure of the AtomAt the center of every atom is the nucleus, which is very small but contains almost all the atom’s mass. It holds the protons and neutrons tightly…