roup 2 Alkaline earth metals
Group 2 elements form 2 ions when they react by losing 2 e
Group 2 elements have e configurations that end in 52
e g Be 152,252
Mg 152,252,2p6,352
atomic radius increases downgroup2
ionisation energy
1st ionisation energydecreases downgroup2
no of shells increasesdown group 2 so more shielding and weaker
ttraction between the nucleus and outer e
outer e also further from the nucleus which weakens attraction
both of these make it easier to remove the outer e and so less energy
needed to remove the outer e
there is also an increase in no of protonsdown the group However
wielding effect overrides an increase in ve charge
Meltingpoints
generally decrease as we go down thegroup
group 2 elements form metallic structures where you have tve
etat ions attracted to a delocalised ve sea of e
e down the
group the size of the metal ion increases but the charge
n the ion and no of delocalised e remains the same too
larger ion means distance between the nuclei in metal ions and
elocalised e is greater weakens the attractive force
this makes it easier to break bondsand hence less energy required
so leads to lower meltingpoints to
Magnesium is an exception due to a structural difference comparedto the
ther group2 metals
Reactions with water
Group 2 elements react with water to form bases Alkaline substances
ence referred to as alkaline Earth metals
e g reaction with water to form metal hydroxides
Sr S 2142011 Sr OH 2 a97 H219
Reactivity with water increases down thegroup no reaction with Be
atom gets larger and e is further ftp.meansuicelfysoraenmdovmeore shielding
o attraction between nucleus and e weaker and hence
ore reactive
Magnesium reacts slowly with cold water but more vigorously with stea
steam produces Magnesium oxide Mgo instead of a hydroxide
Group2 Compounds solubility
Group 2 sulfates and hydroxides have oppositesolubility as we godown
he group
Element sulfates 5042 Hydroxide OH
Magnesium very soluble sparingly soluble
calcium fairly soluble slightlysoluble
strontium slightlysoluble fairly soluble
Barium sparinglysoluble very soluble
general rule if an ion c ve ion has double charge they become less
luble as we godown the groupand if anion has a singlechargetheybecome
ore soluble as we go down the group
Test for sulfates
steps 1 add hydrochloricacid Hcl to remove any carbonates as these
uld precipitate out after step 2 giving a false result
2 add barium chloride
tve result white precipitate of barium sulfate
equations Balt ag 5042 cag Ba2504 s
Bach2 lag 2h50a g Ba504 s
ca ZnClacag
Group 2 elements form 2 ions when they react by losing 2 e
Group 2 elements have e configurations that end in 52
e g Be 152,252
Mg 152,252,2p6,352
atomic radius increases downgroup2
ionisation energy
1st ionisation energydecreases downgroup2
no of shells increasesdown group 2 so more shielding and weaker
ttraction between the nucleus and outer e
outer e also further from the nucleus which weakens attraction
both of these make it easier to remove the outer e and so less energy
needed to remove the outer e
there is also an increase in no of protonsdown the group However
wielding effect overrides an increase in ve charge
Meltingpoints
generally decrease as we go down thegroup
group 2 elements form metallic structures where you have tve
etat ions attracted to a delocalised ve sea of e
e down the
group the size of the metal ion increases but the charge
n the ion and no of delocalised e remains the same too
larger ion means distance between the nuclei in metal ions and
elocalised e is greater weakens the attractive force
this makes it easier to break bondsand hence less energy required
so leads to lower meltingpoints to
Magnesium is an exception due to a structural difference comparedto the
ther group2 metals
Reactions with water
Group 2 elements react with water to form bases Alkaline substances
ence referred to as alkaline Earth metals
e g reaction with water to form metal hydroxides
Sr S 2142011 Sr OH 2 a97 H219
Reactivity with water increases down thegroup no reaction with Be
atom gets larger and e is further ftp.meansuicelfysoraenmdovmeore shielding
o attraction between nucleus and e weaker and hence
ore reactive
Magnesium reacts slowly with cold water but more vigorously with stea
steam produces Magnesium oxide Mgo instead of a hydroxide
Group2 Compounds solubility
Group 2 sulfates and hydroxides have oppositesolubility as we godown
he group
Element sulfates 5042 Hydroxide OH
Magnesium very soluble sparingly soluble
calcium fairly soluble slightlysoluble
strontium slightlysoluble fairly soluble
Barium sparinglysoluble very soluble
general rule if an ion c ve ion has double charge they become less
luble as we godown the groupand if anion has a singlechargetheybecome
ore soluble as we go down the group
Test for sulfates
steps 1 add hydrochloricacid Hcl to remove any carbonates as these
uld precipitate out after step 2 giving a false result
2 add barium chloride
tve result white precipitate of barium sulfate
equations Balt ag 5042 cag Ba2504 s
Bach2 lag 2h50a g Ba504 s
ca ZnClacag
