Definitions on Science Subject Chemistry
Definitions on Science Subject Chemistry
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Chemistry:
Chemistry is the branch of science that studies substances, their composition, and their properties.
Example: Studying how salt dissolves in water is chemistry. -
Matter:
Matter is anything that has mass and occupies space.
Example: Air and water are forms of matter. -
Element:
An element is a pure substance made of only one kind of atom.
Example: Oxygen is an element. -
Atom:
An atom is the smallest unit of an element that takes part in a chemical reaction.
Example: A hydrogen atom is very small. -
Molecule:
A molecule is formed when two or more atoms join together.
Example: A water molecule is made of hydrogen and oxygen. -
Compound:
A compound is a substance formed when two or more elements chemically combine.
Example: Water is a compound. -
Mixture:
A mixture is made by mixing two or more substances without chemical bonding.
Example: Sand and salt mixed together form a mixture. -
Solution:
A solution is a uniform mixture of a solute and a solvent.
Example: Salt water is a solution. -
Solute:
A solute is the substance that dissolves in a solvent.
Example: Sugar is the solute in sugar water. -
Solvent:
A solvent is the substance that dissolves the solute.
Example: Water is the solvent in salt water. -
Solid:
A solid has a fixed shape and volume.
Example: Ice is a solid. -
Liquid:
A liquid has a fixed volume but no fixed shape.
Example: Milk is a liquid. -
Gas:
A gas has neither fixed shape nor fixed volume.
Example: Oxygen is a gas. -
Physical Change:
A physical change changes only the form of a substance, not its nature.
Example: Melting of ice is a physical change. -
Chemical Change:
A chemical change forms a new substance.
Example: Rusting of iron is a chemical change. -
Evaporation:
Evaporation is the process by which a liquid changes into a gas.
Example: Wet clothes dry due to evaporation. -
Condensation:
Condensation is the process by which a gas changes into a liquid.
Example: Water droplets form on a cold glass. -
Melting:
Melting is the process of changing a solid into a liquid.
Example: Ice melts into water. -
Freezing:
Freezing is the process of changing a liquid into a solid.
Example: Water freezes into ice. -
Boiling:
Boiling is the rapid change of a liquid into a gas at a fixed temperature.
Example: Water boils at 100°C. -
Rusting:
Rusting is the slow chemical reaction of iron with air and moisture.
Example: An old iron gate gets rusted. -
Combustion:
Combustion is the process of burning a substance in oxygen.
Example: Burning of wood is combustion. -
Fuel:
A fuel is a substance that produces heat energy when burned.
Example: Coal is a fuel. -
Acid:
An acid is a substance that tastes sour and turns blue litmus red.
Example: Lemon juice is an acid. -
Base:
A base is a substance that tastes bitter and turns red litmus blue.
Example: Soap solution is a base. -
Salt:
A salt is formed when an acid reacts with a base.
Example: Common salt is a salt. -
Indicator:
An indicator is a substance that shows whether a solution is acidic or basic.
Example: Litmus is an indicator. -
Neutralization:
Neutralization is the reaction between an acid and a base to form salt and water.
Example: Acid and base reacting in the stomach is neutralization. -
Alloy:
An alloy is a mixture of two or more metals or a metal and a non-metal.
Example: Brass is an alloy of copper and zinc. -
Corrosion:
Corrosion is the slow destruction of metals by air, water, or chemicals.
Example: Rusting of iron is corrosion. -
Chemical Reaction:
A chemical reaction is a process in which new substances are formed.
Example: Burning paper is a chemical reaction. -
Reactant:
Reactants are substances that take part in a chemical reaction.
Example: Hydrogen and oxygen are reactants in water formation. -
Product:
Products are substances formed after a chemical reaction.
Example: Water is the product of hydrogen and oxygen. -
Separation of Mixtures:
Separation of mixtures is the process of separating substances mixed together.
Example: Handpicking is used to separate stones from grains. -
Filtration:
Filtration is used to separate insoluble solids from liquids.
Example: Tea leaves are separated by filtration. -
Evaporation (Separation):
Evaporation is used to separate dissolved solids from liquids.
Example: Salt is obtained from seawater by evaporation. -
Distillation:
Distillation is used to separate liquids with different boiling points.
Example: Distillation is used to purify water. -
Crystallization:
Crystallization is used to obtain pure solid crystals from a solution.
Example: Sugar crystals are formed by crystallization. -
Saturated Solution:
A saturated solution cannot dissolve more solute at a given temperature.
Example: No more sugar dissolves in water. -
Unsaturated Solution:
An unsaturated solution can dissolve more solute.
Example: More salt can dissolve in water. -
Concentration:
Concentration shows the amount of solute in a solution.
Example: Strong lemonade has high concentration. -
Physical Property:
A physical property can be observed without changing the substance.
Example: Colour of gold is a physical property. -
Chemical Property:
A chemical property describes how a substance reacts.
Example: Iron rusts in air. -
Hard Water:
Hard water contains dissolved salts of calcium and magnesium.
Example: Well water is often hard water. -
Soft Water:
Soft water easily forms lather with soap.
Example: Rainwater is soft water. -
Reversible Change:
A reversible change can be undone.
Example: Freezing of water is reversible. -
Irreversible Change:
An irreversible change cannot be undone.
Example: Burning of paper is irreversible. -
Pure Substance:
A pure substance contains only one kind of particles.
Example: Distilled water is a pure substance. -
Natural Substance:
Natural substances are obtained from nature.
Example: Wood is a natural substance. -
Synthetic Substance:
Synthetic substances are man-made.
Example: Plastic is a synthetic substance.
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