Question | Answer |
the first ionisation energy of an element | is the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions. |
electron shielding | is the repulsion between electrons in different inner shells. shielding reduces the net attractive force from the positive nucleus on the outer shell electrons. |
Successive ionisation energies | are a measure of the energy required to remove each electron in turn |
the second ionisation energy | is the energy required to remove one electron from each ion in one mole of gaseous 1+ ions to from one mole of gaseous 2+ ions. |
a shell | is a group of atomic orbitals with the same principal quantum number, also known as a main energy level. |
an atomic orbital | is a region within an atom that can hold up to two electrons, with opposite spins. |
a sub-shell | is a group of the same type of atomic orbitals (s, p, d or f) within a shell. |
ionic bond | the electrostatic attraction between oppositely charged ions. |
covalent bond | a bond formed by a shared pair of electrons |
metallic bond | the electrostatic attraction between positive metal ions and delocalised electrons. |
a group | is a vertical column in the periodic table. Elements in the same group have similar chemical properties and their atoms have the same number of outer shell electrons |
a dative covalent bond or coordinate bond | is a shared pair of electrons which has been provided by one of the bonding atoms only. |
electronegativity | is a measure of the attraction of a bonded atom for the pair of electrons in a covalent bond. |
a permanent dipole | is a small charge difference across a bond that results from a difference in the electronegativities of the bonded atoms. |
an intermolecular force | is an attractive force between neighbouring molecules |
a permanent dipole- dipole force | is a weak attractive force between permanent dipoles in neighbouring polar molecules |
van der Waals forces | are attractive forces between induced dipoles in neighbouring molecules |