ES Flashcards
halogens
group 7 elements
7 electrons in outer shell
most reactive group of non-metals
none found naturally in elemental form
halogens in ionic compounds
gains an electron from a metal ion to form a halide ion in an ionic compound
colours and physical states of diatomic halogens
F2 - pale yellow gas at room temperature
Cl2 - green gas at room temperature
Br2 - dark red volatile liquid
I2 - shiny grey solid
going down the group halogens…
become darker in colour
MP and BP decrease
become less volatile
decrease in reactivity
strongest oxidising agent HALOGEN
decreases down group - fluorine most oxidising
a halogen can displace a
less reactive halide (eg. fluorine can displace iodide)
oxidation
gaining oxygen
loss of hydrogen
loss of electrons
ON increases
reduction
loss of oxygen
gaining hydrogen
gaining electrons
ON decreases
oxidising agents vs reducing agents
oxidising agents - oxidise others by accepting electrons, are themselves reduced
reducing agents - reduce others by donating electrons, are themselves oxidised
systematic names
include oxidation state of elements/ions with variable oxidation states eg. transition metals
cathode
negative electrode
cations (+ve) ARE REDUCED
anode
positive electrode
anions (-ve) ARE OXIDISED
oxidation of water
H2O»_space; O2 + 4e- + 4H+
at anode
reduction of water
2H2O + 2e-»_space; 2OH- + H2
at cathode
conditions for oxidation of water in electrolysis
O2 produced if salt is sulfate or nitrate
halogen produced if salt is halide