Group 2 chemistry

Question 1

what is the alternative name for group 2 elements?

Answer 1

alkaline earth metals

Question 2

what is the general electronic configuration for group 2?

Answer 2

[X]ns2

Question 3

why is helium not grouped with group 2? what is it grouped with instead?

Answer 3

• instead, it is grouped with the other noble gasses
• due to its chemical and physical properties.

Question 4

which group 2 metals can be cut with a knife?

Answer 4

Ca, Sr, Ba

Question 5

how do group 2 melting points and densities compare to group 1? why?

Answer 5

Higher melting points and densities than the alkali metals
- formation of stronger metallic bonds

Question 6

how are group 2 elements found in nature?

Answer 6

encountered as salts, either in solution or in mineral deposits.

Question 7

are group 1 or group 2 more reactive?

Answer 7

group 1

Question 8

how do you isolate group 2 elements?

Answer 8

using electrolysis, though commercially, some of the elements are extracted via reduction with carbon and other elements.

Question 9

what 2 things can sum to make the activation energy of group 2?

Answer 9

the sum of energy required to form the gaseous M2+ cation (cf. the alkali metals) and the atomisation energy

Question 10

reactivity of group 2 ______ down the group

Answer 10

decreases

Question 11

why do the ionisation energies of Sr and Ba not fit with the linear trend of the rest of group 2?

Answer 11

Poorly shielding d electrons in their electron configurations

Question 12

what beryllium chloride molecule is formed in the gas phase?

Answer 12

linear covalent BeCl2 molecules (same with beryllium hydride)

Question 13

how are halide bridges formed?

Answer 13

by donation of a pair of electrons from Cl to form a coordinate or dative covalent bond – no longer e- deficient.

Question 14

how do you find beryllium chloride in the solid state?

Answer 14

polymerises and shows covalently bonded chains

Question 15

what do Be2+ ions form in aqueous solution?

Answer 15

[Be(H2O)4]2+

(other metal ions form [M(H2O)6]2+

Question 16

why does Be2+ form [Be(H2O)6]2+?

Answer 16

Be2+ is extremely small (steric effects)! The available vacant d-orbitals of the heavier metals also play a role as they can accommodate the lone pair electrons from water molecules.

Question 17

Beryllium hydroxide is ______

Answer 17

amphoteric

Question 18

why can aqueous beryllium hydroxide act as an acid?

Answer 18

the highly polarising Be2+ ion – the coordinated water molecules in aqueous conditions have hydrogen ions that are easily removed from them by a base

Question 19

what 4 ionic salts do group 2 form?

Answer 19

• chlorides
• hydroxides
• carbonates
• sulfates

Question 20

how many group 2 elements form nitrides?

Answer 20

all of them

Question 21

why are the solbilities of group 2 hard to predict?

Answer 21

due to competing effects of decreasing lattice and hydration enthalpies down the group.

Question 22

what is the use of BaSO4?

Answer 22

barium meal

Question 23

the temperature of decomposition of oxysalts ____ down the group

Answer 23

increases

Question 24

what is the diagonal relationship on the periodic table?

Answer 24

Li/Mg example
- similar properties