A-Level Chemistry Unit 1 Section 3

ions are formed

when electrons are transferred from one atom to another

compound ions

group of atoms with overall charge

ammonium

NH4 -

nitrate

NO3 -

hydroxide

OH -

carbonate

CO3 2-

covalent bonding

two or more atoms sharing electrons

single covalent bond

one shared pair of electrons

name the 2 giant covalent structures

graphite and diamond

low

simple covalent compounds have ____ melting points

high

giant covalent structures have ____ melting points

dative covalent bonds

both shared electrons come from the same atom

lone pairs

a pair of unshared electrons

charge cloud

an area where there is a chance of finding an electron

false

T/F bonding pairs repel more than lone pairs

a wedge means

the bond is pointing towards you

3 bonding pairs

trigonal planar bond angle 120°

3 bonding pairs 1 lone pair

trigonal pyramidal bond angle 107°

6 bonding pairs

octahedral bond angle 90°

electronegativity

an atoms ability to attract the bonding pair of electrons

polar bonds occur when

there is a difference in electronegativity between the bonding atoms

a molecule has a permanent dipole when

the charge is distributed unevenly over the whole molecule

polar molecules

molecules with a permanent dipole

3 types of intermolecular forces

van der waals
permanent dipole-dipole forces
hydrogen bonds

van der waals forces

between temporary dipoles. keep changing but present in all atoms

easy

van der waals forces are ____ to overcome

permanent dipole-dipole forces

in substances with permanent dipoles between δ- and δ+ charges on neighbouring molecules

hydrogen bonding occurs when hydrogen is bonded to

fluorine, nitrogen or oxygen

hydrogen bonding

hydrogen forms weak bonds with lone pairs from other atoms

hydrogen bonding gives molecules

uncharacteristically high melting/boiling points

metal elements structure

giant metallic lattice

metallic bonding

electrostatic attraction between positive metal ions and delocalised negative electrons

metal elements have high melting points due to

strong electrostatic forces of attraction between positive ions and negative electrons

good

metals are _____ thermal and electrical conductors

the melting and boiling point of a substance is determined by

the strength of attraction between its particles

polarity

solubility depends on

ionically bonded compounds have

high melting/boiling points and only conduct electricity when molten

simple covalent compounds have

low melting/boiling points and do not conduct electricity

giant covalent structures have

high melting/boiling points and do not conduct electricity

metallic structures have

high melting/boiling points and conduct electricity