Group 7 - The Halogens Flashcards
are halogens reactive
yes
are halogens metals or nonmetals
reactive non metals
how do halogens exist as
diatomic molecules
are diatomic molecules polar or non polar
non polar
what happens to electronegativity down group 7 and why
electronegativity decreases down group 7
because the number of principle energy levels increase
weaker attraction between the nucleus and electrons in the COVALENT BOND
what happens to the boiling point down group 7 and why
boiling point down group 7 increases
*because size of atom increases
*there are more van der waals forces between molecules that need to be broken
what colour and state is fluorine at room temperature
pale yellow gas
what colour and state is chlorine at room temperature
pale green gas
what colour and state is bromine at room temperature
dark red/orange liquid
what colour and state is iodine at room temperature
dark purple/black solid
how can we test the oxidising ability of halogens
by carrying out displacement reactions with aqueous solutions of halogens and aqueous solutions of halide salts
the most oxidising agent halogen will displace a halogen from its salt
what colour is chlorine in aqueous solution
yellow
what colour is bromine in aqueous solution
orange
what colour is iodine in aqueous solution
purple black
what will chlorine oxidise
what will bromine oxidise
what will iodine oxidise
chlorine will oxidise Br- and I-
bromine will oxidise I- but not Cl-
iodine will oxidise nothing
what colour solution is formed when aqueous chlorine reacts with aqueous bromine ions
a yellow solution
what colour solution is formed when aqueous chlorine reacts with aqueous iodine ions
a brown solution formed
what colour solution is formed when aqueous bromine reacts with aqueous iodine ions
a brown solution is formed
what happens when chlorine dissolves in water
when chlorine dissolves in water it forms a mixture of hydrochloric acid (HCL) and chloric(I) acid (HClO). the equilibrium mixture is called chorine water and is pale green in colour showing the presence of Cl2
what type of reaction is chlorine reacting with water
a disproportionate reaction (type of redox reaction) because chlorine is oxidised and reduced
what happens when we add universal indicator paper to chlorine water
if universal indicator paper is added to chlorine water it first turns red since both reaction products are acids (HCl=strong HClO = weak) and then the red colour disappears and the universal paper turns white since chloric(I) acid is a very effective bleach
what happens to chlorine water in the presence of bright sunlight
if chlorine is bubbled through water in the presence of bright sunlight or if the green solution of chlorine water is left in bright sunlight then a colourless gas is produced (oxygen) and the green colour due to the chlorine fades. under these conditions, the chlorine oxidises water into oxygen and the chlorine itself gets reduced into chloride ions
what has been used to sterilise drinking water and swimming baths
chlorine and its compounds
is chlorine toxic and therefore how much should be used in swimming pools and drinking water
yes therefore the concentration of chlorine must only be small amounts
which has the highest concentration of chlorine : swimming pools or drinking water
swimming poools and therefore it is monitored closely to ensure that there’s a high enough concentration to kill bacteria but not enough to be toxic
has the use of chlorine in swimming pools decreased over the years
what has it been replaced by
yes
it’s been replaced with calcium chlorate(I)
