2.1, 2.2, 2.3 definitions

isotopes

atoms of the same element with different numbers of neutrons and different masses

atomic (proton number)

number of protons in a nuclear atom

mass (nucleon) number

the sum of the protons and neutrons in the nucleus

ion

a positively or negatively charged atom or groups of atoms, where the number of electrons is different from the number of protons

relative isotopic mass

the mass of an atom compared to one-twelfth the mass of on atom of carbon-12

relative atomic mass

the weighted mean mass of an atom of an element compared with one-twelfth the mass of an atom of carbon-12

Avogadro constant

the number of atoms per mole of the carobn-12 isotope

mole

amount of substance containing as many elementary particles as there are carbon atoms in exactly 12g of carbon-12

molar mass

the mass per mole of a substance , units of g mol^-1

molar gas volume

that volume per mole of gas molecules at a stated temperature and pressure

empirical formula

the formula that shows the simplest whole-number ratio of atoms of each element present in a compound

molecular formula

a formula which shows the number and types of atoms of each element present in a molecule

molecules

the smallest part of a covalent compound that can exist while still retaining its chemical identity

concentration

the amount of solute in moles or grams dissolved in 1dm³ of solution

standard solution

a solution of a known concentration

stoichiometry

the ratio of the amount, in moles, of each substance in a chemical equation

acid

proton donor

base

proton acceptor

alkali

a type of base that dissolves in water to produce OH- ions

salt

the product of a reaction where the H+ ions in an acid are replaced by metal or ammonium ions

cation

a positively charged ion

anion

a negatively charged ion

hydrated

a crystalline compound containing water molecules

anhydrous

a crystalline compound containing NO water molecules

water of crystallisation

water molecules that are bonded into a crystalline structure of a compound

oxidation number

a measure of the number of electrons that an atom uses to bond with atoms of another element

oxidation

loss of electrons

reduction

gain of electrons

reducing agent

a reagent that reduces another species

oxidising agent

a reagent that oxidised another species