group 2 Flashcards
what is the trend in atomic radius down the group
increases
number of shells increases
what is the trend in 1st ionisation energies down the group
decreases
number of shells increases
weaker attraction between the nucleus and outer electron
what is the trend in meting point down the group
decreases
size of ion increases
weaker electrostatic attraction between the positive ions and delocalised electrons
what is the bonding and structure of group 2 ions
giant metallic lattice
strong electrostatic attraction between positive ions and the sea of delocalised electrons
what is the trend in the rate of reaction with water down the group
increases
more shielding
outer electrons are further away from the nucleus
weaker attraction between the nucleus and outer electrons
therefore electrons are lost more easily
what are the observations with group 2 and the reaction with water
more vigorous fizzing
reactions warm up quicker
less precipitate forms
down the group is more soluble
the equation for Mg and H2O
Mg(s) + 2H2O(g) → Mg (OH)2(s) + H2(g)
equation for Ca and H2O
Ca(s) + 2H2O(g) → Ca (OH)2(s) + H2(g)
equation for Sr and H2O
Sr(s) + 2H2O(g) → Sr (OH)2(aq) + H2(g)
equation for Ba and H2O
Ba(s) + 2H2O(g) → Ba (OH)2(aq) + H2(g)
what is the reaction between Mg and steam
Mg(s) + H2O(g) → MgO(s) + H2(g)
what is the observations of the reaction between Mg and steam
white flame
white powder
bright spark
what is the trend in solubility of hydroxides down the group
solubility increases
what is the trend in the pH of hydroxides down the group
Ph increases
more hydroxide ions in the solution due to the increasing solubility, therefore the solution is more alkaline
what is the test for hydroxide or magnesium ions
magnesium chloride and NaOH forms Mg (OH)2
a white precipitate is formed
Mg2+(aq) + 2OH-(aq) → Mg(OH)2(s)
what is the trend in solubility for sulfates
decreases
what is the test for sulfate or barium ions
sulfuric acid and a barium salt forms BaSO4
a white precipitate
Ba²⁺ (aq) + SO₄²⁻ (aq) ⇒ BaSO₄ (s)
why must a sulfate be acidified with HCl before testing for ions
to remove any carbonate ions that may interfere with the results
CO3 2− ( aq ) + 2H+ ( aq ) → CO2 ( g ) + H2O ( l )
what are the two methods to separating a precipitate from a mixture
reduced pressure filtration via a Buchner Flask
gravity filtration
what is the diagram for a Buchner Flask
how does gravity filtration work
filter the precipitate from the solution
wash the residue with deionised water
dry by pressing between 2 sheets of filter paper or leave to dry by the air
