group 7 Flashcards
what colour is chlorine
a green gas
what colour is bromine
orange brown liquid
what colour is iodine
a grey solid
why does bp and mp increase down the group
as the atomic radius increases
what is chlorine used for
-sterilised water
-kills harmful bacteria- makes potable water
-too much can be harmful and toxic
-used to make pesticides and plastics
what is bromine used for
-purify water
-flameproofing agent
-pesticides
-medicines
-dyes
what is iodine used for
-used as an antiseptic to sterilise wounds
what happens to iodine at room temp when heated
turns into a purple gas via sublimation
what is sublimation
solid –> gas
what happens when halogens react with metals
-react vigorously with group 1 elements, particularly if the metal is heated first
-makes a metal halide
-clouds of a metal halide are formed
what happens in the equation for the reaction of metals with halides
metal + halogen = metal halide
-halogen is the oxidising agent
-reduction when reacting
e.g 1/2Cl2 + e- –> Cl-
what is the trend with reactivity down the group
-decreases down the group
how does atomic radius affect reactivity
as atomic radius increases due to more shells and e-
how does electron shielding affect reactivity
electron shielding increases so the distance from the outer shell to the nucleus is larger therefore the attraction is weaker so e- are gained more easily in a reaction
what is a disproportionation reaction
the same element is both reduced and oxidised
whats the equation for the reaction of chlorine and water
Cl2(aq) + H2O(aq) –> HCLO(aq) + HCL
whats the equation for the reaction of chlorine and aqueous sodium hydroxide
Cl2(aq) + 2NAOH(aq) –> NaCl(aq) + NaClO(aq) + H2O(l)
what happens to chlorine when in a solution
turns pale green
what happens when bromine when in a solution
yellow solution
what happens when iodine is added to a solution
turns to a brown solution
what is the test for halogens
silver nitrate
AgNO3(aq)
what happens when chlorine is added to AgNO3
a white precipitate is formed
Ag+(aq) + Cl-(aq) –> AgCl(s)
what happens when bromine is added to AgNO3
a cream precipitate is formed
Ag+(aq) + Br(aq) –> AgBr(s)
what happens when iodine is added to AgNO3
a yellow precipitate is formed
Ag+(aq) + I(aq) –> AgI(s)
