Question
The table shows some properties of four Group I elements.
(a) (i) Complete the table by estimating:
-
- the boiling point of sodium
- the relative hardness of lithium. [2]
(ii) Predict the physical state of lithium at 200°C.
Give a reason for your answer. [2]
(b) Potassium reacts with water.
2K + 2H2O → 2KOH + H2
Describe two observations when potassium reacts with water.[2]
1
2
(c) Lithium is extracted by the electrolysis of molten lithium chloride.
(i) Name a non-metal used to make the electrodes.[1]
(ii) Give one property, other than the conduction of electricity, that makes this substance suitable for use as an electrode.[1]
(iii) State the products of the electrolysis of molten lithium chloride at:[2]
the negative electrode (cathode)
the positive electrode (anode)
(d) Lithium chloride conducts electricity when molten and when in aqueous solution.
Give two other physical properties of lithium chloride that show it is an ionic compound.[2]
1
2 [Total: 12]
Answer/Explanation
Ans:
(a)(i) boiling point of Na any values between 800 and 1300 (°C) (inclusive of these values) (1)
hardness of Li: any value above 0.70 (MPa) up to a maximum of 5.0 (MPa) (1)
(a)(ii) liquid (1)
200 °C is above the melting point and below the boiling point / 200 °C is between the melting and boiling points (1)
(b) 1 mark each for any 2 of:
-
- bubbles / effervescence / fizzing
- potassium disappears
- potassium moves around
- potassium floats on the surface
- (bursts into) flame / sparks / explodes
BUT
colour of flame is lilac = 2 marks
(c)(i) carbon / graphite
(c)(ii) inert / unreactive
(c)(iii) negative electrode: lithium (1)
positive electrode: chlorine (1)
(d) high boiling point / high melting point (1)
soluble in water (1)
Question
This question is about elements in the Periodic Table.
(a) The table shows some properties of five elements, P, Q, R, S and T.
Use only the elements shown in the table to answer this question.
State which two of the elements, P, Q, R, S and T, are covalent molecules.
Give two reasons for your answer.
elements …………………………………………………….. and ……………………………………………………..
reason 1 …………………………………………………………………………………………………………………….
reason 2 …………………………………………………………………………………………………………………….
(b) Element T is on the left-hand side of the Periodic Table.
Suggest whether its oxide is acidic or basic.
Give a reason for your answer.
(c) Krypton is an element in Group VIII of the Periodic Table.
Explain, using ideas about electronic structure, why krypton is unreactive.
(d) Sodium is an element in Group I of the Periodic Table. Iron is a transition element.
Iron has a higher melting point and higher boiling point than sodium.
Give two other ways in which the properties of transition elements differ from the properties of
Group I elements.
1 ……………………………………………………………………………………………………………………………….
2 ……………………………………………………………………………………………………………………………….
(e) The table compares the reactivity of four metals with dilute hydrochloric acid.
Put the four metals in order of their reactivity.
Put the least reactive metal first.
(f) Hot iron reacts with steam. The reaction is reversible.
Complete the equation by writing the symbol for a reversible reaction in the box.
(g) Steel is an alloy of iron.
State the meaning of the term alloy.
Answer/Explanation
Answer:
(a) Q AND S (1)
low melting points (1)
poor conductor (of electricity) / does not conduct (electricity) (1)
(b) basic (oxide) AND
T is a metal / metal oxides are basic
(c) has a complete outer (electron) shell / has a full outer (electron) shell
(d) 1 mark each for any 2 of:
• transition elements have a high(er) density / Group I has a low(er) density
• transition elements form coloured compounds / Group I compounds are not coloured
• transition elements form ions with different charges / Group I forms only one type of ion
• transition elements are good catalysts / Group I elements not catalysts
(e) copper < nickel < iron < calcium (2)
if 2 marks not scored, 1 mark for:
1 consecutive pair reversed / calcium < iron < nickel < copper
(f) \(\leftrightarrow \)
(g) mixture of metal with another element
Question
The table shows some properties of four Group I elements.
(a) (i) Complete the table by predicting:
● the boiling point of rubidium
● the atomic radius of potassium.
(ii) Describe the trend in the melting point of the Group I elements down the group.
(iii) Deduce the physical state of potassium at 60°C.
Explain your answer.
(b) Caesium is a radioactive element with a proton number of 55.
(i) Define proton number.
(ii) State one industrial use of radioactive isotopes.
(c) Sodium hydride, NaH, reacts with iron(III) oxide.
(i) Balance the equation for this reaction.
\(Fe_2O_3 + 3NaH → …..Fe + …..NaOH\)
(ii) Explain how this equation shows that iron(III) oxide is reduced.
Answer/Explanation
Answer:
(a) (i) boiling point of Rb: any values between 675 and 755 (°C) (inclusive of these values) (1)
atomic radius of K: any values between 0.195 and 0.245 (nm) (inclusive of these values) (1)
(ii) decreases (1)
(iii) solid (1)
60 °C is below the melting point / the melting point is above 60 °C (1)
(b) (i) number of protons in the nucleus of an atom / number of positive charges in the nucleus of an atom
(ii) any suitable, e.g. detecting leaks in pipes / measuring thickness of paper / energy production
(c) (i) 2 (Fe) (1)
3 (NaOH) (1)
(ii) iron(III) oxide loses oxygen / it loses oxygen