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patterns and propreties of metals, Group II metals - alkaline earth metals…
patterns and propreties of metals
group 1: alkali metals
reaction with cold water
combustion
release hydrogen gas and the metal hydroxide (exothermic)
hydrogen released burns with metals characteristic flame color
metal + water --> metal hydroxide + hydrogen
example
sodium + water --> sodium hydroxide + hydrogen
2Na(s) + 2H2O(l) --> 2NaOH(aq) + H2(g)
not many uses because very reactive and tarnish easilly (have to be stored under oil)
melting points and hardness decrese gradually go down group
density and reactivity increases
potassium slightly less dense than sodium
Group II metals -
alkaline earth metals
Flame tests for alkaline metals
every metal in a Bunsen flame gives a characteristic colour
similar reactivity trends to Group I, but less reactive
reactivity increases going down the gropu
beryllium top = least reactive, barium bottom = most reactive
magnesium =
slow
reaction in
cold water
,
vigourous reaction
with
steam
over heated magnesium
calcium
strong reaction
with
cold water
ALUMINIUM
very expensive until 1886 cause sodium or potassium were used
1886 - Charles Hall and Paul Heroult used electrolysis to obtain the metal
most common metal on earth
major ore =
bauxite
aluminium cloride
aluminium
PROPERTIES
light
,
strong
,
good conductivity
used in modern cars and airplanes
cause of a layer of aluminium oxyde it's
protected
from corrosion
food packaging and windows