Keywords

• Element


  A substance containing only one type of atom e.g. Fe, Br2, Ag
• Compound


  A substance containing more than one type of atom chemically bonded to each other (with ionic or covalent bonds) eg. FeSO4
• Mixture


  A combination of two or more substances that are not chemically bonded to each other e.g. sodium chloride (NaCl) in water (H2O)
• Molecule


  A small number of atoms held together with covalent bonds e.g. I2 or CO2
• Particle 


  A general term used to describe any small portion of matter (e.g. atom, molecule ect.)
• Atom


  The smallest component of an element e.g. Fe, Br2, Ag
• Periodicity


  A repeating trend in the properties if elements along periods
• Metaloids 


  Non-metals with some metallic properties; semi-metals
• Nucleon


  A proton or neutron
• Cation


  A positively charged ion
• Anion


  A negatively charged ion
• Isotopes


  Atoms of the same element with a different number of neutrons and different masses
• Mass (Nucleon) Number


  Number of protons + neutrons in the nucleus of an atom
• Atomic (proton) number


  Number of protons in the nucleus of an atom
• Relative atomic mass


  The weighted mean mass of an atom of an element when compared to 1/12 of the mass of one atom of C-12
• Relative Isotopic Mass


  The mass of one atom of an isotope when compared with 1/12 of the mass of one atom of C-12
• Orbital


  A region of space within an atom (around the nucleus) that can hold up to two electrons with opposite spin
• Ions


  An ion is an atom or group of atoms that has become positively charged or negatively charged by losing or gaining electrons
• Octet rule


  The tendency for atoms to acquire a Noble Gas electron configuration
• Elemental ion


  When one type of atom has become positively charged or negatively charged by losing or gaining electrons
• Polyatomic ion


  When a group of atoms has become positively charged or negatively charged by losing or gaining electrons
• Valency


  A measure of the number of electrons and atom or group of atoms uses in bonding with another species
• Univalent (divalent, trivalent)


  One electron is used in bonding with another species (two... three...)
• Oxidation number 


  A measure of the number of electrons an atom uses to bond to atoms of a different element
• Covalent bond


  The sharing of a pair of electrons between two atoms
• Metallic bond


  The electrostatic attraction of positive metal ions to delocalised electrons
• Ionic bond


  The electrostatic attraction between oppositely charged ions
• Acid


  A proton donor (releases H+ ions when in a solution)
• Strong acid


  A proton donor that completely dissociates into its ions in aqueous solution
• Weak acid


  Proton donor which partially dissociates in an aqueous solution
• Salt


  A compound formed when the H+ ion in an acid is replaced by a metal or another positive ion (e.g. NH4+)
• Base


  A proton acceptor
• Alkali


  A soluble base that releases OH- ions in a solution
• Mole


  The amount of substance containing as many particles as there are carbon atoms in exactly 12g of C-12
• Avagadro's constant


  The number of particles per mole of a subs6ance (6.02 x 10^23)
• Molar mass


  The mass per mole of a substance gmol^-1
• Empirical formula


  The simplest whole number ratio of atoms of each element present in a compound
• Molecular formula 


  The actual number of atoms of each element in a molecule
• Hydrated


  When water of crystallisation is present in a crystal compound
• Anhydrous


  When all the waters of crystallisation have been removed from a compound