Chemistry definitions

chemistry definitions

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  • Created on: 19-04-11 11:04
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Gcse Chemistry Definitions
Melting Solid changing into a liquid
Freezing Liquid changing into a solid
Condensation Gas/vapour changing into a liquid
Evaporation Liquid changing into a gas/vapour
Melting Point Temperature at which a solid turns into a liquid
Freezing Point Temperature at which a liquid changes into a solid
Boiling Point Temperature at which a liquid changes into a vapour at
atmospheric pressure
Diffusion The random movement and mixing if different particles with each
Filtration Separating an insoluble solid from a liquid due to particle size
Distillation Separating a liquid from a solution by evaporation and condensing
due to a difference of boiling points
Fractional Distillation Separating a mixture of liquids due to a difference of boiling
Atomic Number The number of protons in an atom
Atom A neutral particle where the number of electrons equals the
number of protons. The smallest unit of an element, having all the
characteristics of that element
Mass Number The sum of the protons and neutrons
Nucleus The centre of the atom which contains protons and neutrons
Isotope Atoms of the same element with the same atomic number and
different number of neutrons
Element Made of only one type of atom
Compound Made of two or more different atoms chemically joined together
Mixture Made of two or more different components which are not
chemically joined together
Banbridge Academy
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Group The columns in the Periodic Table. The Group Number equals the
number of electrons in the outer shell
Period The rows of the Periodic Table. The Period Number equals the
number of shells used by the electrons of the atom.
Alkali Metals Group 1 elements. The most reactive metals (more reactive as the
group is descended)
Alkaline Earth Metals Group 2 elements
Halogens Group 7 elements. The most reactive non metals (more reactive as
the group is ascended)
Noble Gases Group 0 elements.…read more

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Relative Formula Mass The sum of the atomic masses of elements in a
Mole The formula mass expressed in grams.
Mole = mass
Formula mass
Exothermic Reaction A reaction which gives out heat.
Endothermic Reaction A reaction which takes in heat.
pH A scale of 0 ­ 14 which identifies solution as acidic,
neutral or alkaline.
Base A substance with a pH higher than 7, and which
has a high concentration of hydroxyl ions.…read more

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Electrolysis A reaction where an ionic compound is split up by
Electrolyte The ionic compound which is split up by electrolysis.
Anode The positive terminal (electrode).
Cathode The negative terminal (electrode)
Reversible Reaction A reaction where reactants change to products which
can then change back to reactants.
Fertilisers Chemical compounds ( eg. Ammonium compounds)
which are added to soil to increase the quantity and
quality of crops.…read more

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Solubility The maximum mass of solute which will dissolve in
100g of solvent to form a saturated solution at that
particular temperature
Hard Water Water which does not rather readily with soap.
A Homologous Series A homologous series is a group of molecules with the
same general formula and the same functional group.
They have similar physical and chemical properties
(albeit with trends e.g.…read more


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