SC17: Groups in the Periodic Table - Paper 2

Question 1

Explain how elements are classified in different groups of the periodic table: (4)

Answer 1

• The periodic table positions elements based on their properties which are linked to their electronic configurations. (1)
• Elements with the same number of electrons in the outer shell and hence similar chemical properties are placed in the same group. (1)
• This allows us to use the table to predict the properties of elements based on their position. (1)
• Groups 1, 7 and 0 are elements which have been classified into their respective groups using the periodic table. (1)

Question 2

Explain the properties of alkali metals: (2)

Answer 2

• Soft (1)
• They have relatively low melting points. (1)

Question 3

Explain what happens when the following elements react with water: (3)

• Lithium (1)
• Sodium (1)
• Potassium (1)

Answer 3

• Lithium: Bubbles fiercely on the surface of the water. (1)
• Sodium: Melts into a ball and fizzes about the surface. (1)
• Potassium: Bursts into flames and flies about the surface. (1)

Question 4

Explain what happens to the reactivity as you go down group 1: (1)

Answer 4

It increases. (1)

Question 5

Explain why reactivity increases as you go down group 1: (4)

Answer 5

• As you go down group 1, the number of shells of electrons increases by 1. (1)
• This means that the outermost electron gets further away from the nucleus, so there are weaker forces of attraction between the outermost electron and the nucleus. (1)
• Less energy is required to overcome the force of attraction as it gets weaker, so the outer electron is lost more easily. (1)
• So, the alkali metals get more reactive as you descend the group. (1)

Question 6

State the colours and physical states of the following at room temperature: (6)

• Chlorine (2)
• Bromine (2)
• Iodine (2)

Answer 6

Colours:

• Chlorine: Pale yellow-green (1)
• Bromine: Red-brown (1)
• Iodine: Purple-black (1)

Physical States:

• Chlorine: Gas (1)
• Bromine: Liquid (1)
• Iodine: Solid (1)

Question 7

Explain the pattern of melting and boiling points of the halogens: (1)

Answer 7

• The melting and boiling points of the halogens increase as you go down the group. (1)

Question 8

Explain the chemical test for chlorine: (3)

Answer 8

• The test for chlorine makes use of litmus paper. (1)
• If chlorine gas is present, damp blue litmus paper will be bleached white. (1)
• It may turn red briefly before bleaching, as acids are produced when chlorine comes into contact with water. (1)

Question 9

State the reactions of the following halogens with other metals to form metal halides: (3)

• Chlorine (1)
• Bromine (1)
• Iodine (1)

Answer 9

• Chlorine: Chlorine + Sodium –> Magnesium Chloride (Cl2 + Na —> NaCl2) (1)
• Bromine: Bromine + Sodium –> Sodium Bromide (Br2 + Na —> NaBr) (1)
• Iodine: Iodine + Sodium –> Sodium Iodide (I2 + Na —> NaI) (1)

Question 10

Explain what the halogens chlorine, bromine and iodine form: (1)

Answer 10

They form hydrogen halides which dissolve in water to form acidic solutions. (1)

Question 11

Explain the pattern of reactivity in Group 7: (1)

Answer 11

It decreases as you go down the group. (1)

Question 12

Explain why halogen displacement reactions are classified as redox reactions: (1)

Answer 12

• Oxidation and reduction take place together at the same time in the same reaction. (1)

Question 13

Explain the halogen reactivity in terms of electronic configuration: (1)

Answer 13

• It goes down because as you go down the group, the atoms become larger which means the distance between the outer most shell and the nucleus is greater which leads to it being less reactive. (1)

Question 14

Explain why Group 0 elements are chemically inert: (1)

Answer 14

They have full outer shells. (1)

Question 15

Explain the uses of Group 0 elements: (4)

Answer 15

• Helium is used for filling balloons and weather balloons as it is less dense than air and does not burn. (1)
• Neon, argon and xenon are used in advertising signs. (1)
• Argon is used to provide an inert atmosphere for welding and to fill electric light bulbs. (1)

Argon is used in low energy light bulbs. (1)

Question 16

Explain the physical properties of Group 0 elements: (3)

Answer 16

• The noble gases have very low melting and boiling points. (1)
• They show an increase in boiling point as we move down the group due to an increase in the relative atomic mass. (1)
• Elements further down the group have higher boiling points but these still lie below 0 ºC. (1)

Question 17

Define the term alkali metals: (1)

Answer 17

A group of very reactive metals found in group 1 of the periodic table. (1)

Question 18

Define the term reactivity: (1)

Answer 18

The energy or the force of a chemical substance to undergo a reaction. (1)

Question 19

Define the term halogens: (1)

Answer 19

An element in group 7 of the periodic table. (1)

Question 20

Define the term diatomic: (1)

Answer 20

2 atoms chemically bonded together. (1)

Question 21

Define the following terms:

• Disinfectants (1)
• Bleach (1)

Answer 21

• Disinfectants: Something that destroys or neutralizes disease-carrying microorganisms. (1)
• Bleach: To take colour out of something. (1)

Question 22

Define the term displacement reactions: (1)

Answer 22

When a more reactive element displaces a less reactive element from one of its compounds. (1)

Question 23

Define the following terms: (2)

• Oxidation: (1)
• Reduction: (1)

Answer 23

• Oxidation: A reaction in which oxygen is added to a chemical and there is a loss of electrons by an atom or negative ion. (1)
• Reduction: A reaction in which a substance loses oxygen or gains electrons. (1)

Question 24

Define the term redox: (1)

Answer 24

A reaction in which both oxidation and reduction occur. (1)

Question 25

Define the following terms: (2)

• Reduced: (1)
• Oxidised: (1)

Answer 25

• Reduced: The gain of electrons, loss of oxygen or gain of hydrogen. (1)
• Oxidised: The loss of electrons from a substance. (1)

Question 26

Define the term noble gases: (1)

Answer 26

An unreactive gas in group 0 of the periodic table. (1)