All Definition Of Chemistry For Class 9th [A to Z]

 AllDefinition Of Chemistry For Class 9th [A to Z]

Alcosols: The colloidal solution in which the dispersion medium is alcohol.

Anion: Negatively charged ion.

Atom: Atom is the smallest particle of an element that can take part in a chemical reaction.

Atomic Mass Unit: Quantity of mass equal to one-twelfth of the mass of an atom of carbon-12.

Atomic number: The number of protons present in the nucleus of an element.

Avogadro's number: The number of atoms/molecules of a substance present in one gram atom/molecule of it.

Boiling point: Temperature at which a liquid boils and changes rapidly into a gas at atmospheric pressure.

Cation: Positively charged ion.

Centrifugation: Process of separating liquids from very small solid particles by spinning.

Chemical change: Change in which chemical composition and chemical properties of the reacting substances undergo a permanent change.

Chromatography: Technique used for the separation of a mixture of solutes brought about by dynamic partition or distribution of dissolved materials (solids) between mobile phase and stationary phase.

Coagulation: The process of precipitation and settling down of the discharged solution  particles.

Cohesion: Inter-molecular attraction by which the particles of a matter are bound to one another.

Colloidal solution: Heterogeneous mixture in which particles having size between 10-7 to 10-4 cm are dispersed in a continuous dispersion medium.

Compounds: Pure substance which is composed of two or more elements chemically combined in a definite or fixed proportion by mass.

Concentration: The amount of solute dissolved in a unit quantity (volume or mass) of a solution.

Condensation: Process of changing a gas (or vapour) to a liquid by cooling.

Crystallisation: Process that separates a pure solid in the form of its crystals from a solution.

Decantation: Process of separating an insoluble solid from a liquid by allowing the solid to settle and pouring off the liquid.

Density: Mass per unit volume.

Diffusion: The intermixing of particles(atom or ion) of two different types of matter on their own.

Distillation: Process of converting a liquid into vapour, condensing the vapour and collecting the liquid, called distillate.

Electron: A negatively charged particle found in the atoms of all the elements.

Electrophoresis: Movement of colloidal particles under the influence of electric field.

Elements: The substance that cannot be split up into two or more simpler substances by the usual chemical methods of applying heat, light or electric energy.

Evaporation: Process of conversion of a liquid into vapour without necessarily reaching the boiling point.

Filtration: Process of separating insoluble solid that is present as small particles from a liquid by passing them through a filter.

Fractional Distillation: Process used for the separation of a mixture of two or more liquids that have different boiling points.

Freezing: Process in which a liquid material is changed into solid state.

Freezing point: Temperature at which a liquid substance is changed to a solid state under a given pressure.

Fusion: The process in which solid substance changes into liquid on heating.

Gram Atomic Mass: The atomic mass of an element express in grams is known as gram atomic mass.

Heterogeneous mixture: Heterogeneous mixture are the mixture in which the composition is not uniform throughout the mixture.

 

Homogeneous mixture: Homogeneous mixture are the mixture in which the composition is uniform throughout the mixture.

Humidity: Amount of water vapours present in air.

Hydrosols: The colloidal solution in which the dispersion medium is water.

Isobars: Atoms having same mass number but having different atomic number.

 

Isotopes: Atoms of the same element having same atomic number and chemical properties but different atomic masses.

Ion: Ion is the positively or negatively charged atom (or group of atoms).

Latent heat of fusion: Amount or quantity of heat required to convert unit mass of the solid into the liquid without a change in temperature.

Latent heat of vaporisation: Amount or quantity of heat required to convert unit mass of a liquid into the vapour state at its boiling point without a change in temperature.

Lyophilic colloids: Colloids which directly pass into colloidal state when brought in contact with the solvent.

Lyophobic colloids: Colloids which do not easily pass into colloidal state when brought in contact with the solvent.

Mass number: The total number of protons and neutrons exist in the nucleus of an atom.

Matter: Anything that occupies space and has mass.

Melting point: The temperature at which a solid melts to become a liquid at atmospheric pressure (760mm of Hg).

Metal: An element that is malleable, ductile and conducts electricity.

Metalloids: Elements which show some properties of metals and some other properties of non-metals.

Mixture: Substance which consists of two or more elements or compounds not chemically combined together.

Mole: Amount of a substance which contains the same number of particles as the number of carbon atoms present in 12 g of 12C isotope of carbon.

Molecular Mass: Sum of the atomic masses of all atoms in a molecule of the substance.

Molecule: Smallest particle of a substance which can exist in the free state and exhibits all physical and chemical properties of that substance.

 

Neutron: A neutral particle present in the nucleus of an atom.

Non-metal: An element that is neither malleable nor ductile, and poor conductor of heat and  electricity.

Nucleus: A small positively charged part at the centre of an atom.

Physical change: Change in which only the physical properties of substance get changed while its chemical composition remains unchanged.

Proton: A positively charged particle found in the atoms of all the elements.

Pure substance: Substance which is made up of only one kind of particles.

Relative Molecular Mass: The number of times the molecule of the substance is heavier than one-twelfth of an atom of carbon-12.

Saturated solution: Solution in which no more solute could be dissolved at a fixed temperature.

Solvent: The component which is present in larger proportion in solution.

Solubility: The maximum amount of a solute that can be completely dissolved in 100 g of a solvent at a specified temperature.

Solute: The component which is present in smaller proportion in solution.

Solution: The homogeneous mixture of two or more substances.

Sublimation: Process of changing of a solid directly into vapours on heating and of vapours into solid on cooling.

Suspension: Heterogeneous mixture in which fine particles of a solid are dispersed throughout any medium (liquid or solid) without dissolving in it.

Tyndall effect: Phenomenon of scattering of light by the colloidal particles.

Unsaturated solution: Solution in which more solute could be dissolved at any fixed temperature.

Valence Electrons: The electrons exist in the outermost shell of an atom.

Valency: Number of atoms of hydrogen with which one atom of a given element could combine.

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