General trends in Group 7 Flashcards
the 5 elements of Group 7 are
fluorine chlorine bromine iodine astatine
give the state which each element of Group 7 is in at room temp.
fluorine- gas chlorine- gas bromine- liquid iodine- solid astatine- solid
the trend for melting tempersture down group 7 is
an increase in melting temperature down the group
the trend in boiling temperature down group 7 is
an increase in boiling temp. down the group
the trend in electronegativity down group 7 is
a decrease in electronegativity down the group
all halogens exist as (type of molecule).
this means the boiling and melting temps. depend on
- diatomic molecules
- the strength of the intermolecular forces between the molecules
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
- 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