Data

Copy and paste the text below. It is read-only. Select All

Isotopes are atoms of the same element with a different number of neutrons Atomic number is the number of protons in the nucleus of an atom mass number is the number of particles in the nucleus An ion is a positively or negatively charged atom or covelently bonded group of atoms Relative isotopic mass is the mass of an atom of an isotope compared with 1/12 of the mass of an atom of carbon-12 Relative atomic mass Ar is the weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of carbon-12 relative molecular mass Mr is the weighted mean mass of a molecule compared with 1/12 of the mass of an atom of carbon-12 Relative formula mass is the weighted mean mass of a formula unit compared with 1/12 of the mass of an atom of carbon-12 Amount of substance is the quantity whose unit is the mole. Chemists use 'amount of substance' as a means of counting atoms The Agrovado Constant NA is the number of atoms per mole of the carbon-12 isotope (6.02x10 23 mol-1) A mole is the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope Molar mass M is the mass per mole of a substance. The units of molar mass are g mol-1 The emperical formula is the simplest whole-number ratio of atoms of each element present in a compound A molecule is a small group of atoms held together by covelent bonds The molecular formula is the actual number of atoms of each element in a molecule Molar volume is the volume per mole of a gas. the units of molar volume are dm3 mol-1. At room temperature and pressure, the molar volume is approximately 24.0dm3 mol-1 The concentration of a solution is the amount of solute in a mol, dissolved per 1dm3 (1000cm3) of solution A standard solution is a solution of a know concentration. Standard solutions are normally used in titrations to determine unknown information about another substance A species is any type of particle that takes place in a chemical reaction Stoichiometry is the molar relationship between the relative quantities of substances taking part in a reaction An acid is a species that is a proton donor A base is a species that is a proton acceptor An alkali is a type of base that dissolves in water forming hydroxide ions, Oh-(aq) ions A salt is any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion, such as the ammonium ion, NH4 A cation is a postively charged ion An anion is a negatively charged ion Hydrated refers to a crystalline compound containing water molecules Anhydrous refers to a substance that contains no water molecules Water of crystallisation refers to water molecules that form an essential part of the crystalline structure of a compound