chemistry - trial exam paper 1 definitions

relative atomic mass

the average weighted mean mass of an atom relative to 1/12th the mass of carbon-12

relative isotopic mass

the mass of an individual atom of a particular isotope relative to 1/12th the mass of carbon-12

isotopes

atoms of the same element with the same number of protons but a different number of neutrons

first ionisiation energy

the energy required to remove one electron from each atom in one mol of atoms in the gaseous state

second ionisation energy

the energy required to remove one electron from each singly charged ion in one mol of ions in the gaseous state

orbital

a region within an atom that can hold upto 2 electrons with opposite spins

mass spec steps

vaporisation

ionisation

acceleration

deflection

detection

covalent bond

the strong electrostatic attraction between the 2 positively charged nuclei and shared pair of electrons

ionic bonding

the strong electrostatic attraction between oppositely charged ions

isoelectronic

ions that have the same electronic configuration

electronegativity

an atoms ability to attract a shared pair of electrons in a covalent bond

periodicity

a repeating pattern across different periods

oxidation

increase in oxidation number, loss of electrons

reduction

decrease in oxidation number, gain of electrons

oxidising agent

electron acceptor, gains electrons so is reduced

reducing agent

electron donor, loses electrons so is oxidised

disproportionation

when an element of the same species is simultaneously oxidised and reduced

metallic bonding

the strong electrostatic attraction between the positively charged ionic lattice and sea of delocalised electrons

enthalpy change

heat energy measured at a constant temperature

standard enthalpy of formation

enthalpy change when one mole of a substance is formed from its constituent elements with all reactants and products at 298K and 100KPa

standard enthalpy of combustion

enthalpy change when one mole of a substance is completely burned in oxygen with all reactants and products at 298K and 100KPa

standard enthalpy of neutralisation

enthalpy change when one mole of water is formed in a reaction between an acid and alkali at 298K and 100KPa.

Hess’s law

the enthalpy change in a reaction is independent of the route taken