Key Terms Flashcards
Define Isotope
Same number of protons, different number of neutrons
Define an Ion
A particle where the number of electrons does not equal the number of protons
Define Half-Life
Time taken for the radioactivity of a substance to fall to half its initial value
Define an Atomic Orbital
A region in an atom that can hold up to two electrons with opposite spins
Define Molar 1st Ionisation Energy
Energy required to remove one mole of electrons from one mole of its gaseous atoms
Define one mole
The amount of any substance that contains the same number of particles as there are atoms in 12g of carbon 12
Relative atomic mass
The average mass of one atom of the element relative to one-twelfth the mass of one atom of carbon 12
Relative isotopic mass
Mass of an atom of an isotope relative to one-twelfth the mass of an atom of carbon 12
Relative molecular mass
Average mass of a molecule relative to one-twelfth the mass of an atom of carbon 12
Define enthalpy
The heat content of a system
Define enthalpy change
The heat added to a system at a constant pressure
Define standard enthalpy change of formation
The enthalpy change when one mole of a substance is formed from its constituent elements in their standard states under standard conditions
Define standard enthalpy change of combustion
Enthalpy change when one mole of a substance is completely combusted in oxygen under standard conditions
State Hess’s Law
“The total enthalpy change for a reaction is independent of the route taken from the reactants to the products”
State Le Chateliers Principle
“If a system at equilibrium is subjected to change, equilibrium tends to shift so as to minimise the effect of the change”
