flame tests and trends of group 7 Flashcards
Magnesium flame test
no color
Lithium flame test
red
sodium flame test
yellow/orange
potassium flame test
lilac
rubidium flame test
red/purple
caesium flame test
blue/violet
beryllium flame test
no color
calcium flame test
brick red
strontium flame test
crimson red
barium flame test
apple green
How and why does the melting and boiling temperature change down group 7?
They increase down group 7, because the instantaneous dimple -induced dipole attraction forces between the diatomic halogen molecules increase in strength down group 7 because the number of electrons and therefore the size of electron cloud increases so there’s an increase in boiling and melting points down group 7
What happens when iodine is warmed?
It is sublimated (changes from solid to gas directly)
What causes an increase in electronegativity?
- The bigger the nuclear charge
- The shorter the distance between the nucleus and the bonding pair of electrons
- The fewer the shielding of inner electron, so when there are less energy levels surrounding it
Which group and element in the periodic table have the highest electronegativity?
Group 7
Fluorine
What is the trend in reactivity down group 7?
Reactivity decreases down group 7, because electronegativity decreases down the group and the halogens react by gaining electrons or becoming negatively polarized so a decrease in electronegativity means that they aren’t able to do that as strongly.
