General trends in Group 7

Question 1

the 5 elements of Group 7 are

Answer 1

fluorine
chlorine
bromine
iodine
astatine

Question 2

give the state which each element of Group 7 is in at room temp.

Answer 2

fluorine- gas
chlorine- gas
bromine- liquid
iodine- solid
astatine- solid

Question 3

the trend for melting tempersture down group 7 is

Answer 3

an increase in melting temperature down the group

Question 4

the trend in boiling temperature down group 7 is

Answer 4

an increase in boiling temp. down the group

Question 5

the trend in electronegativity down group 7 is

Answer 5

a decrease in electronegativity down the group

Question 6

all halogens exist as (type of molecule).

this means the boiling and melting temps. depend on

Answer 6

• diatomic molecules

- the strength of the intermolecular forces between the molecules

Question 7

explain how instantaneous dipole-induced dipole attraction are formed between halogen molecules and how this explains the trend in boiling and melting temps. down the group

Answer 7

• two atoms in the diatomic molecule of halogens are identical, so the shared pair of electrons is shared equally between the two atoms
• this molecule is therefore non-polar
• the two positive nuclei are in fixed positions, but the electron density can fluctuate, so the centres of positivity and negativity do not coincide all of the time
• this creates a temporary dipole, or instantaneous dipole
• the neighbouring molecule will then become an induced dipole