chapter 8 Flashcards
what is metallic bonding?
strong electrostatic attraction between metal cations and delocalised electrons
what are the properties of metals?
high electrical conductivity when solid and molten
high melting and boiling points
insoluble
what is the structure of simple molecular lattices?
strong covalent bonds between atoms in molecules
weak intermolecular forces between molecules
what is the structure of giant covalent lattices?
atoms held together by network of strong covalent bonds
whats the test for carbonates?
add dilute nitric acid
carbonates react to form CO2
if presents then bubbles of gas form
whats the test for sulfates?
add barium nitrate
white precipitate forms (barium sulfate)
what is the test for halide ions?
add silver nitrate solution
what are the positive results for the halide test?
chlorine - white
bromine - cream
iodine - yellow
what halide ion is soluble in dilute ammonia?
chlorine
what halide ion is soluble in concentrated ammonia?
bromine
what halide ion is not soluble in any ammonia?
iodine
what is the order of tests to do?
carbonate
sulfate
halides
(silver carbonate or silver sulfate can form)
what is the test for ammonia?
add aqueous sodium hydroxide
test gas released with moist pH paper
paper will turn blue
what happens down the group for metal hydroxides (group 2)?
increases solubility
pH/alkalinity increases
what is the trend down the group for halogens?
reactivity decreases
boiling point increases (increased strength of londons forces due to more electrons
what does a halogen want to do in a reaction?
gain an electron
REDUCTION
oxidising agent
what is the colour of chlorine in water?
pale green
what is the colour of bromine in water?
orange
what is the colour of iodine in water?
brown
what is the colour of fluorine at RTP?
pale yellow gas
what is the colour of chlorine at RTP?
pale green gas
what is the colour of bromine at RTP?
red brown liquid
what is the colour of iodine at RTP?
shiny grey-black solid
what is the colour of chlorine when a non-polar solvent (e.g. cyclohexane) is added?
layer of pale green
what is the colour of bromine when a non-polar solvent (e.g. cyclohexane) is added?
layer of orange
what is the colour of iodine when a non-polar solvent (e.g. cyclohexane) is added?
layer of purple
what is disproportionation?
redox reaction in which the same element is both oxidised and reduced
what are the benefits of chlorine use?
kills bacteria present in water to make it safe to drink
what are the risks of chlorine use?
extremely toxic gas
can react with water to form chlorinate hydrocarbons (suspected carcinogen)
what agent are group 2 elements?
reducing agents as they gain 2 electrons
what is the general equation for the reaction between group 2 elements and oxygen?
Mg (s) + 1/2 O2 (g) –> MgO (s)
what do group 2 elements form when they react with water?
form an alkaline hydroxide
general formula = M(OH)2 and hydrogen gas
what is the reactivity trend down the group of group 2 metals?
reactivity increases down the group
what do group 2 elements form when reacting with a dilute acid?
salt and hydrogen
e.g. Mg + 2HCl –> MgCl2 + H2
what do group 2 oxides do when they react with water?
release hydroxide ions
what can group 2 elements be used for in real life?
calcium hydroxide added to fields to increase pH of acidic soils
medicine (e.g. indigestion tablets, antacids)
