Group 2 elements Flashcards
atomic radius _ down group 2
because:
increases
energy level added and hence weaker force of attraction felt
metallic radius is measure of
size
melting point _ down group 2
and why
decreases delocalised electrons (in their own energy level) are further away from nucleus and strength of metallic bond decreases
density _ down group 2
why?
increases Generally
as atomic radius increases so do mass and volume but mass at greater rate which is proportional to density
how do group 2 elements react
lose 2 electrons from S-orbital
group 2 reactivity _ down the group
why?
increases
there is greater shielding effect and distance because of increased energy levels hence easier to remove outer shell electron
ionisation energy _ down the group
decreases
group 2 metals burn in oxygen to form _ which is _ in nature
white solid oxide
basic (dissolve to form hydroxide)
reactivity of metals with water down the group _ and forms _
increases
metal hydroxide
metals react with steam to form
metal oxide and H2 gas
use of calcium oxide
used to neutralise acid in soil
why beryllium is not an alkali earth metal
amphoteric rather than alkaline behvaior of compounds
reactivity with oxygen _ down group
increases
barium stored in oil because
rapidly vigourously reacts with O2 in air
flame test of Ca, Sr, Ba, Mg compounds
Burn in O2: Ca- brick red color Sr- red Ba- light green Mg- white
How metals burn at atomic level
metal loses 2e- and donates to O
alkalinity _ down group because ..
increases
cos solubility increases down group: more soluble=more dissociation/able to donate more OH-
alkalinity _ down group because …
increases
cos solubility of hydroxides increases down group: more soluble=more dissociation/able to donate more OH-
white ppt (as not transition) or sol
solubility of hydroxides and sulfates(why for this) _ down
hydroxide- inc
sulfates- dec bcos lattice energy and enthalpy change of hydration decrease hence applying hess law the value of enthalpy chnage of solution becomes more endothermic
carbonates of grp 2 are _ in water
insol
carbnotes react with dil acid to give
salt+h2o+co2
which grp 2 sulfates (formed from reacting with dil h2so4) are sol and insol
mgso4-sol
rest-insol
grp 2 nitrate salts are _ in water
all soluble
thermal decomposition of grp 2 carbonates
give off metal oxide + co2
thermal decomposition of grp 2 nitrates
metal oxide + no2 + o2
temperature of thermal decomposition _ down grp
increases
stability of nitrates _ down group hence _ temp required
increases
higher
uses of CaCO3, Ca(OH)2
CaCO3- rocks for building, marble for tiles, cement making
Ca(OH)2- neutralize soil aka slaked lime
cement making:
high temp of kiln CaCO3 decomposes to CaO+CO2 and the quick lime is roasted with clay to make cement
-cement can be mixed with sand to increase strength
why does solubility of sulfates decrease down group
1) larger the cation, weaker lattice so lattice energy decreases as becomes less endo
2) weaker cations bond with water less exo so E change of hydration decreases
hence E of sol becomes more endothermic hence more difficult to dissolve
so 1 has mor value than 2 relatively because 1 decreases less compared to 2
process of hydroxides dissolving
ionic lattice breaks as ions dislodge as water attracts ions. this process is endo to break ionic bonds
then new bonds between ions and polar water are formed
