Some Definitions…

You need to know at least these definitions before the exams…

try to learn them in small bitesize amounts. Ask your friends or parents to test you or write out some flash cards with the word on one side and the definition on the other.

Relative Atomic Mass (Ar) of an element is the average mass of the atoms of an element relative to the mass of the atoms of Carbon-12 for which Ar = 12 exactly.

First Ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous monopositive ions

Mg(g) –> M+g + e

Shielding is the effect of the electrons in the inner shells that reduces the pull of the nucleus on the electrons in the outer shell of an atom. Thanks to shielding, the electrons in the outer shell are attracted by an “effective nuclear charge” which is less than the full charge on the nucleus.

Electron Affinity – is the energy change per mole to add one mole of electrons to one mole of gaseous atoms to form one mole of anions in their gaseous phase.

X(g) + e –> Xg

Isotopes are atoms of the same element (identical proton number) but a different number of neutrons