An oxide is a compound that forms when oxygen combines with another element.
Magnesium (Mg) has the atomic number 12. It is number 12 on the periodic table.
Magnesium oxide (MgO) is an ionic compound. Magnesium loses electrons and oxygen gains electrons, forming ions with opposite charges.
An oxide is a compound that forms when oxygen combines with another element. Oxygen can combine with many different elements to make different oxides.
For example, when magnesium combines with oxygen, it forms magnesium oxide (MgO). Another example is carbon dioxide (CO₂), which is made from carbon and oxygen.
So, an oxide always contains oxygen combined with another element. Oxides can be made from different elements, so there are many different types of oxides.
A salt is a compound that can form when an acid reacts with a base. This type of reaction is called a neutralization reaction.
Acids are a type of substance with their own chemical properties.
Acids taste sour because they interact with taste receptors on our tongue.
Acid particles can release hydrogen as H⁺ ions.
These are three important types of substances in chemistry.
Acids are substances that can have a sour taste.
They usually have a pH below 7.
Strong acids can be dangerous and can damage materials.
Cellular respiration is the chemical process cells use to release energy from glucose (sugar).
Glucose comes into the cell.
In aerobic respiration, the cell uses oxygen.
Glucose is broken down through several chemical reactions.
Global warming means Earth's average temperature is increasing.
Humans burn fuels like coal, petrol, and natural gas.
Burning fuel is a chemical reaction.
The battery works by a process called oxidation Hydroxide ion combines with electrostatic and zinc atom forming zinc hydroxide This process is called oxidation and made three electron, electron stalls in the brass
Static electricity is a build-up of electric charges on the surface of an object. These charges stay in one place until they suddenly move or discharge.
Rubbing a balloon on your hair makes your hair stand up.
A balloon sticks to a wall after being rubbed on your clothes.
Walking on a carpet and touching a metal doorknob gives a tiny shock.
Electricity is a form of energy created by the movement of tiny particles called electrons. It flows through wires and provides power to many devices we use every day.
A light bulb glows using electricity.
A fan spins using electricity.
A television works with electricity.
Electricity is a form of energy that comes from the movement of tiny particles called electrons. When these electrons move through materials like metal wires, they create an electric current that can power many devices.
A source like a battery or power station provides energy that pushes electrons to move.
Examples:
A battery is a device that stores chemical energy and changes it into electrical energy. Inside the battery, chemicals react and push tiny particles called electrons to move. The movement of electrons creates electric current that can power devices.
Examples:
🔦 Flashlights use batteries to produce light.
⌚ Watches use batteries to keep running.
🎮 Remote controls use batteries to send signals.
Lightning is a giant electric spark that happens inside clouds or between a cloud and the ground.
Inside a thundercloud, tiny ice crystals (tiny pieces of ice) and water droplets (tiny drops of water) bump into each other.
These collisions (hits) create electric charges (electric energy).
The top (upper part) of the cloud becomes positive (+).
Clouds are large groups of tiny water droplets, ice crystals, or both that float in the Earth's atmosphere. They form when water from oceans, lakes, rivers, and other water bodies evaporates into the air. As the water vapor rises
higher, it cools and changes into tiny droplets or ice crystals. Billions of these tiny droplets gather together to form a cloud.
Clouds come in many shapes, sizes, and heights. Some are white and fluffy, while others are dark and thick. They play an important role in Earth's weather by bringing rain, snow, or hail and by helping regulate the planet's temperature. Without clouds, the water cycle and weather would not work the way they do.
Conductor lets electricity pass through because Electrons are freely to move.
conductor lets electricity pass but not that easily because Electrons are tightly packed.
Properties of the Periodic Table
1. Elements are arranged by atomic number
Elements are placed in order by the number of protons they have.
2. Rows are called periods
The horizontal lines in the periodic table are called periods.
Evaporation is the process in which a liquid changes into a gas (vapour) from its surface without boiling.
Liquid particles are always moving.
When they absorb heat energy, they move faster.
Some particles gain enough energy to overcome the forces holding them together.
Atoms bond together to become stable.
Electrons are transferred.
Happens between a metal and a non-metal.
Combination Reaction Two or more substances combine to form one new substance. A + B → AB
Decomposition Reaction One substance breaks down into two or more simpler substances. AB → A + B
Displacement Reaction One element replaces another element in a compound. A + BC → AC + B
Double Displacement Reaction Two compounds exchange their ions to form two new compounds. AB + CD → AD + CB
Neutralization Reaction An acid reacts with a base to form salt and water. Acid + Base → Salt + Water
A decomposition reaction happens when one substance breaks down into simpler substances.
🍎 Food rotting after many days.
🍂 Fallen leaves breaking down in the soil.
🌍 The Sky’s Invisible Shield: The Story of Ozone! ☀️🛡️
High up in the sky, there is a special, invisible blanket of gas called the ozone layer. It acts like Earth’s natural sunscreen, protecting us from the sun's harshest rays!
Here is the simple science story of how it works:
🏹 The Sun's Sneaky Arrows
The sun gives us light and warmth, but it also shoots out invisible, super-fast energy rays called UV rays. [1]
Think of these rays like tiny, flying invisible arrows.
Combination Reaction
A combination reaction is a type of chemical reaction in which two or more substances combine to form a single new substance.
It is one of the simplest types of chemical reactions because multiple reactants join together to produce only one product.
Key Points:• Two or more reactants combine.• Only one product is formed.• A new substance is produced.• Also called a synthesis reaction.• It can release heat or absorb heat, depending on the reaction.
Combination reactions are important in nature, industries, and many everyday chemical processes, making them a fundamental concept in chemistry.
Two or more substances combine.
Forms one new substance.
A + B → AB
A chemical reaction is a natural process in which one or more substances are converted into new substances with different properties. During a chemical reaction, the atoms in the original substances rearrange by breaking existing chemical bonds and forming new ones. The atoms themselves are not created or destroyed—they are simply reorganized into new combinations. As a result, new products are formed that may have different colours, smells, states, or other physical and chemical properties. Chemical reactions are happening constantly in our daily lives, such as when food is cooked, fuel burns, plants make food, metals rust, and our bodies digest food to produce energy.
Solids, Liquids, and Gases
These are the 3 main states of matter.
Has a fixed shape
Has a fixed size
Particles are packed tightly
subatomic particles
no
Think of an atom as a tiny LEGO brick. Everything in the world—your toys, the air, and even you—is built from billions of these bricks!
Here are the 3 basic parts inside every atom:
The Nucleus: This is the center of the atom. It’s like the "brain" or the sun in a mini solar system.
Protons: These live in the center and have a positive (+) charge. They decide what kind of atom it is (like gold or oxygen).
Neutrons: These also live in the center. They are neutral, meaning they don't have a charge; they act like "glue" to hold the protons together.
Electrons: These are tiny and have a negative (-) charge. They zip around the outside of the center incredibly fast.
Organic Chemistry
Study of Carbon Chemicals
Carbon Element
Joins with Many Atoms
Forms Different Substances 🧪
Kinetics = The speed of a chemical reaction.
It helps us understand:
Why some reactions are fast ⚡
Why some reactions are slow 🐢
example
substances change into new substances.
🍳 Cooking food – when we cook rice, eggs, or bread.
molecules found in living things
body grow, get energy, and stay healthy.
Equilibrium means balance.
Seesaw ⚖️
Book on a table 📚
Chemical reactions 🧪\
An acid is a substance that usually tastes sour.
Examples of acids:
🍋 Lemon juice
🍊 Orange juice
🧴 Vinegar
Niels Bohr was a famous scientist who helped us understand atoms.
🇩🇰 He was born in Denmark in 1885.
⚛️ He studied atoms, the tiny building blocks of everything.
An atom is the tiny building block of everything in the world.
Everything you see—air, water, trees, animals, and even you—is made of atoms!
Think of atoms like LEGO blocks. 🧱
Just like LEGO blocks join together to build things, atoms join together to make everything.
A physical change is when something changes its shape or size, but it stays the same thing.
👉 No new thing is made.
🧊 Ice melting into water
✂️ Cutting paper
Reduce, Reuse, Recycle: Minimize consumption, reuse items, and recycle materials to conserve resources and energy.
Sustainable transport: Use public transportation, carpool, walk, or cycle instead of driving private vehicles.
Conserve energy: Turn off lights and appliances when not in use to reduce electricity consumption from fossil fuels.
Proper waste management: Dispose of waste properly and avoid burning garbage, plastic, or dry leaves.
Increase green cover: Plant more trees to absorb pollutants like carbon dioxide and maintain ecological balance.
what is pollution
Pollution is the introduction of harmful substances or energy into the environment that cause damage to ecosystems and living organisms.
It can be in the form of a solid, liquid, or gas, and includes things like trash, chemicals, and exhaust. types of pollution . air
. water
.noise
.soil
Ions are atoms with a positive or negative charge formed when an atom gains or loses electrons, and an ionic bond is the electrostatic attraction between these oppositely charged ions.
Ionic bonds typically form between a metal and a non-metal, like sodium and chlorine in table salt (NaCl), where the metal atom transfers its electrons to the non-metal atom to form a stable compound.
An atom's structure consists of a dense, positively charged nucleus at the center, made of protons and neutrons, and negatively charged electrons orbiting the nucleus in shells or orbitals. The number of protons in the nucleus determines the element's atomic number, while a neutral atom has an equal number of protons and electrons. Electrons exist in specific energy levels, governed by quantum mechanics, and their arrangement determines the atom's chemical properties.
Metals typically have properties like luster, malleability, and ductility, making them shiny, able to be hammered into thin sheets, and drawn into wires, respectively. They are also excellent conductors of heat and electricity, have high melting and boiling points, and are generally solid at room temperature (except for mercury).
An atom is the basic building block of all ordinary matter, consisting of a dense central nucleus surrounded by a cloud of negatively charged electrons. The nucleus is made of positively charged protons and neutral neutrons. Atoms of different elements have different numbers of protons, which defines the element, such as carbon or oxygen.
The three most common states of matter are solid, liquid, and gas, while a fourth, plasma, is also fundamental. Solids have a definite shape and volume, liquids have a definite volume but take the shape of their container, and gases have no definite shape or volume. Plasma, often found in stars and lightning, consists of super-excited particles.
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