Inorganic chemistry and the periodic table

Question 1

What are the trends down group 2

Answer 1

-Forms positive ions more readily
-Forms covalent bonds less readily
-Oxides become stronger bases
-(elements become increasingly more metallic in character)

Question 2

what are 3 Physical properties of group 2 metals?

Answer 2

-All conduct electricity
-Mp/Bp decrease down the group (except Mg)
-Hardness decreases down the group

Question 3

What happens to the first ionisation energies down group 2 and why?

Answer 3

First ionisation energies decrease down the group as the atoms get larger and valance electrons are further away from the nucleus.

Question 4

How is the increase in nuclear charge compensated for?

Answer 4

Increase in shielding by a larger number of inner electrons

Question 5

How does reactivity change down group 2?

Answer 5

Reactivity increases as valance electrons are further from the nucleus and have less attraction to the nucleus making reactions more exothermic

Question 6

How do group 2 metals react with oxygen (apart from Ba which forms a peroxide)

Answer 6

-Forms ionic oxides with the formula XO
-Reactions increase in vigour down the group

Question 7

How do group 2 elements react with chlorine?

Answer 7

-All react vigorously to produce ionic chlorides with the formula XCl2
-All soluble in water producing hydrated ions with the formula [X(H2O)6]2+

Question 8

How do group 2 elements react with water?

Answer 8

-React Rapidly to form an alkaline suspension of metal hydroxide and hydrogen bubbles
-(Mg burns in steam to form oxide and hydrogen)

Question 9

How does group 2 oxides react with water?

Answer 9

-MgO reacts slowly with water to form hydroxide
-Other oxides react rapidly with water to form the hydroxide

Question 10

How does group 2 oxides react with dilute acids?

Answer 10

Forms salt and water

Question 11

How does group 2 hydroxides react with acids?

Answer 11

Forms salt and water

Question 12

How soluble are group 2 hydroxides?

Answer 12

-Be(OH)2 / Mg(OH)2 are not very soluble
-Down group 2 solubility of hydroxides increases (due to increase in ionic radii)

Question 13

How soluble are group 2 sulfates?

Answer 13

-Solubility decreases down the group

Question 14

How does the thermal stability of nitrates/carbonates in group 1 and 2?

Answer 14

-Stability decreases in both groups; group 2 less stable than group 1 because of the 2+ cation produced making it more ‘polarising’

Question 15

How do group 2 nitrates decompose?

Answer 15

-Decompose with heat to give metal oxide + brown fumes of nitrogen dioxide
-Lithium decomposes the same way due to it being extremely polarising

Question 16

How do group 1 nitrates decompose apart from lithium?

Answer 16

Produce metal nitrate + oxygen

Question 17

Apart from barium carbonate which is thermally stable, how do the other group 2 carbonates decompose?

Answer 17

Form metal oxide + carbon dioxide

Question 18

Group 1 carbonates are thermally stable apart from…

Answer 18

lithium carbonate which forms metal oxide + CO2

Question 19

How do you test the relative rates of thermal decomposition of group 1 and 2 carbonates?

Answer 19

-Equal amounts of carbonates in test tubes
-Bunsen burner on blue flame
-Heat test tube 1 by 1 and time for limewater to go cloudy

Question 20

Group 1 flame test colours:

Answer 20

-Lithium - Red
-Sodium - Yellow
-Potassium - Lilac

Question 21

Group 2 flame test colours:

Answer 21

-Calcium - Brick Red
-Strontium - Crimson Red
-Barium - Apple Green

Question 22

How do colours form in a flame test?

Answer 22

-Heat causes vaporisation of compound and promotion of an electron to higher energy level (excitation)
-Electron falls back down to original energy level (de-excitation) and the difference in energy between orbitals dictates colour produced

Question 23

How to conduct a flame test?

Answer 23

-Dip Platinum wire into HCl then flame then back into HCl then into substance and then flame

Question 24

What are the trends in group 7:

Answer 24

-Atomic size increase down group
-Mp/Bp increase down group due to increasing London forces
-Electronegativity decreases down group due to reducing attraction between valance electron and nucleus

Question 25

Which is the strongest/weakest group 7 oxidising agent?

Answer 25

-Strongest - Chlorine
-Weakest - Iodine

Question 26

What is the strongest/weakest group 7 reducing agent?

Answer 26

-strongest - Iodine
-weakest - chlorine

Question 27

What is electron affinity?

Answer 27

-The energy change when one electron is added to each atom in 1 mole of gaseous atoms

Question 28

How is domestic bleach made?

Answer 28

-aa disproportionation reaction where Cl is bubbled into an alkali solution

Question 29

Disproportionation reaction in cold alkali vs hot alkali with chlorine:

Answer 29

-Cold - chloride and chlorate(I) formed
-Hot - chloride and chlorate(V) formed