Chemistry Unit 1 Definitions 5.0 / 5 based on 4 ratings ? ChemistryASCCEA Created by: Megan EdwardsCreated on: 08-03-13 21:34 Avagadro's Number The number of atoms in 12.000g of carbon 12. 1 of 31 Mole The amount of substance which contains the Avogadro number of atoms, molecules or groups of ions. 2 of 31 Molar mass The mass of one mole of a substance. 3 of 31 Anhydrous (salt) A salt which contains no water of crystallisation 4 of 31 Hydrated (salt) A salt which contains water of crystallisation 5 of 31 Water of crystallisation Water chemically bonded within a crystal structure. 6 of 31 Atomic Number The number of protons in the nucleus of an atom 7 of 31 Mass number The number of protons and neutrons in the nucleus of an atom 8 of 31 Relative atomic mass (RAM) The average mass of an atom of an element relative to one-twelfth of the mass of an atom of carbon 12 9 of 31 Relative molecular mass (RMM) The average mass of a molecule relative to one-twelfth of the mass of an atom of carbon 12 10 of 31 Relative isotopic mass (RIM) The mass of an atom of an isotope of an element relative to one-twelfth of the mass of an atom of carbon 12 11 of 31 Isotopes Atomes of the same element with the same number of protons but a different number of neutrons 12 of 31 Molecular ion An ion formed by the removal of an electron from a molecule 13 of 31 First ionisation energy The energy required to convert one mole of gaseous atoms into gaseous ions with a single positive charge 14 of 31 Second ionisation energy The energy required to convert one mole of gaseous ions with a single positive charge into gaseous ions with a double positive charge 15 of 31 Third ionisation energy The energy required to convert one mole of gaseous ions with a double positive charge into gaseous ions with a triple positive charge. 16 of 31 Ground state An electronic configuration in which all the electrons are in the lowest available energy levels 17 of 31 Covalent bond A shared pair of electrons between 2 atoms 18 of 31 Octet Rule When forming a compound, an atom tends to gain, lose or share electrons as to achieve 8 in its outer shell 19 of 31 Coordinate (Dative) bond A shared pair of electrons between 2 atoms. One atom provides both electrons 20 of 31 Delocalised electrons Outer electrons do not have fixed positions but move freely 21 of 31 Electronegativity The extent to which an atom attracts the bonding electrons in a covalent bond 22 of 31 Polar bond A covalent bond in which there is unequal sharing of the bonding electrons 23 of 31 Bonding pair A pair of electrons shared between 2 atoms 24 of 31 Lone pair A pair of unshared electrons in the outer shell of an atom 25 of 31 Intermolecular Between neighbouring molecules 26 of 31 Oxidation Loss of electrons/increase in oxidation number 27 of 31 Reduction Gain of electrons/decrease in oxidation number 28 of 31 Redox Oxidation and reduction in the same reaction 29 of 31 Bond enthalpy The energy required to break one mole of a specific bond 30 of 31 Disproportionation Oxidation and reduction of the same species in the same reaction. 31 of 31
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