4.2 - Group 7 Flashcards
what are halogens
group 7 elements
what type of bonding and substances are halogens
covalent bonding
simple moleculular substances
what are the properties of group 7 elements
all are diatomic
colours get darker down the group
MP/BP increases down the group
what colour is fluorine
very pale yellow
what state is fluorine
gas
what colour is chlorine
pale green
what state is chlorine
gas
what colour is bromine
brown
what state is bromine
liquid
what is bromine like
volatile, releases brown fumes
what colour is iodine
dark grey
what state is iodine
solid
what is iodine like
sublimes, releases purple fumes
what colour is astatine
black
what state is astatine
solid
what happens when halogens react with metals
they form ionic compounds
what happens to the electrons in a halogen and metal reaction
the outer shell electrons are transferred to the halogen
what type of reaction is a halogen and metal reaction
redox
why does the halogen change its name and what to in a halogen and metal reaction
it changes from a halogen to halide
so chlorine would go from chlorine atom to chloride ion
what happens to the reactivity of halogens down the group
they get less reactive
what do all halogens need to do to fill their outer shell
gain an electron
why is it easier for halogens to gain an electron and form a halide ion further down the group
atoms have more electron shells
the extra electron is further from the nucleus
so its attraction to the nucleus is weaker
what is the chemical test for chlorine
damp blue litmus paper turns white
– because the chlorine acts as a bleaching agent so it removes the colour from the paper
what do more reactive halogens do to less reactive halogens when they react
they can displace the less reactive halogens
what colour is Cl2 (aq)
colourless
what colour is Br2 (aq)
yellow
what colour is I2 (aq)
brown
what colour is the salt KCl
colourless
what colour is the salt KBr
colourless
what colour is the salt KI
colourless
what is the reaction between KCl and Br2
no change
stays yellow
what is the reaction between KCl and I2
no change stays brown
what is the reaction between KBr and Cl2
Cl2 + 2KBr –> Br2 + 2KCl
chlorine displaces bromine
colourless –> yellow
what is the reaction between KBr and I2
no change
stays brown
what is the reaction between KI and Cl2
Cl2 + 2KI –> I2 + 2KCl
chlorine displaces iodine
colourless –> brown
what is the reaction between KI and Br2
Br2 + 2KI –> I2 + 2KBr
bromine displaces iodine
yellow –> brown
what is the reactivity trend of chlorine, bromine and iodine
chlorine> bromine> iodine
what is the colour change due to
the halogens present because the salts are colourless
what does the more reactive halogen do to the halide
the more reactive halogen atom steals an electron from the halide ion in the salt
