10 group 7
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what are group 7 elements called?
halogens
describe what fluorine looks like
pale yellow gas
describe what chlorine looks like
pale green gas
describe what bromine looks like
orange/brown liquid
describe what iodine looks like
grey solid
what happens to boiling point down group 7? why?
increases due to increased van de waals forces
what is the trend in electronegativity down group 7? why?
decreases due to atomic radius increasing and more shielding
what is the trend in reactivity down group 7?
decreases
do halogens get more or less oxidising when going down group 7?
less oxidising
what is the rule for halide displacement reactions?
if the halide is lower than the halogen in the periodic table, halogen will displace
what does KBr react with? write an equation and the observation
Cl2 Cl2 + 2Br- -> 2Cl- + Br2 orange solution made
what does KI react with?
Cl2 and Br2
write the equation and state the observation of the reaction of KBr with Cl2
Cl2 + 2Br- -> 2Cl- + Br2 orange solution made
write the equation and state the observation of the reaction of KI with Br2
Br2 + 2I- -> 2Br- + I2 brown solution
what is the chemical name for bleach?
sodium chlorate NaClO
write the equation for bleach
2NaOH + Cl2 -> NaClO + NaCl + 2H2O
what type of reaction is the one for bleach?
disproportionation reaction
what is a disproportionation reaction?
a reaction where an element is both oxidised and reduced
what is reduced and oxidised in the reaction for bleach?
Na
how can you kill bacteria in water?
by adding chlorine gas
what is the equation for the reaction between water and chlorine?
H2O + Cl2 -> 2H+ + Cl- + ClO-
what kind of reaction is the reaction used to kill bacteria in water?
disproportionation reaction
what is both reduced and oxidised in the reaction for killing bacteria in water?
Cl
what are the disadvantages for putting chlorine in drinking water?
• toxic (irritates respiratory system) • liquid chlorine causes chemical burns