Topic 4 Inorganic and Periodic Table

Question 1

What is thermal decomposition?

Answer 1

A reaction in which a compound decomposes when heated.

Question 2

What are ionic equations?

Answer 2

Chemical equations showing only the reaction ions in a solution leaving out any spectator ions.

Question 3

What are spectator ions?

Answer 3

Ions which are present in a solution but take no part in the reaction.

Question 4

What is an ionic precipitation reaction?

Answer 4

A reaction which produces a solid precipitate on mixing two solutions containing ions.

Question 5

What is a trend?

Answer 5

The way in which a property increases or decreases along a series of elements or compounds.

E.g. Properties down a group or across a period in the periodic table.

Question 6

What are bases?

Answer 6

The chemical opposite of an acid. Bases such as OH⁻ accept hydrogen ions where as acids donate hydrogen ions.

Question 7

What is a basic oxide?

Answer 7

A metal oxide which reacts with acids to form salts and water. The oxide ion acts as a base and accepts hydrogen ions from the acids.

Question 8

What is thermal stability?

Answer 8

An indication of the ease with which compounds decomposed when heated. Compounds are stable if the tend not to decompose into their elements or other compounds. Stable compounds at room temperature can become more or less stable as conditions change.

Question 9

What is polarising power?

Answer 9

An indication of the extent to which a positive ion is able to distort the electron cloud around a neighbouring negative ion. The larger the charge on a positive ion and the smaller its size, the greater its polarising power will be.

Question 10

What is a displacement reaction?

Answer 10

A type of redox reaction which can be used to compare the relative strengths of metals as reducing agents and non-metals as oxidising agents.

Question 11

What are ionisation energies?

Answer 11

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous ions.

Question 12

What occurs when oxygen reacts with group 2 metals?

Answer 12

• All group 2 metals burn to form a metal oxide
• Magnesium burns vigorously with a bright white flame
• Calcium burns with a brick-red flame
• Strontium burns with a carmine red flame
• Barium burns with a pale green flame and forms large amounts of barium peroxide (Ba₂O₂)
• All group 2 oxides are white, ionic compounds

Question 13

What occurs when chlorine reacts with group 2 metals?

Answer 13

All group 2 metals form white, ionic compounds when heated with chlorine.

Question 14

What occurs when water reacts with group 2 metals?

Answer 14

• The vigour of the reaction increase down the group
• Magnesium reacts slowly with cold water but rapidly with steam
• Calcium reacts quite quickly with cold water to give a milky suspension of calcium hydroxide
• Strontium and Barium both react vigorously and form hydroxides.

Question 15

What occurs when water reacts with group 2 metal oxides?

Answer 15

• All group 2 metals react with water to give metal hydroxides.
• The solubility of the metal hydroxides increase down group 2

Question 16

What are the flame colours of lithium, sodium, potassium, calcium, strontium and barium?

Answer 16

Lithium - Crimson Red
Sodium - Yellow
Potassium - Lilac
Calcium - Brick Red
Strontium - Carmine Red
Barium - Pale Green

Question 17

What processes take place in a flame test?

Answer 17

A platinum wire is dipped into concentrated hydrochloric acid and placed in the hottest part of the Bunsen flame. (if the flame is coloured repeat until the wire doesn’t colour the flame).

Dip the wire back into concentrated hydrochloric acid then into the solid that is being tested. Place in the hottest part of the flame and observe the colour.

Question 18

What are the physical properties of group 7 elements (halogens)?

Answer 18

Fluorine: Pale-Yellow Gas, MT = 53.5K, BT = 85K

Chlorine: Green-Yellow Gas, MT = 172K, BT = 239K

Bromine: Brown volatile Liquid, MT = 266K, BT = 332K

Iodine: Dark grey Solid, MT = 387K, BT = 457K

MT = Melting Temperature
BT = Boiling Temperature

Question 19

What is the trend in electronegativity and reactivity in group 7?

Answer 19

Electronegativity - Decreases down the group

Reactivity - Decreases down the group

Question 20

How do group 1 and 2 carbonates decompose?

Answer 20

Group 1 (except lithium) - None of these carbonates decompose when heated.

Group 2 (+ lithium) - When heated, these carbonates decompose to give the metal oxide and CO₂.

Question 21

How do group 1 and 2 nitrates decompose?

Answer 21

Group 1 (except lithium) - Decompose when heated to give the metal nitrile and O₂

Group 2 (+ lithium) - Decompose when heated to give NO₂ + O₂ + metal oxide

Question 22

What is the trend in decomposition of group 2 carbonates?

Answer 22

Decomposition becomes more difficult, due to the cation becoming bigger and less polarising.

Mg²⁺ is the smallest cation and therefore is the least thermally stable.