Question
The diagrams show part of the structures of five substances, $\mathbf{A}, \mathbf{B}, \mathbf{C}, \mathbf{D}$ and $\mathbf{E}$.
(a) Answer the following questions about these structures.
Each structure may be used once, more than once or not at al
l.
(i) Which two of these structures, $\mathbf{A}, \mathbf{B}, \mathbf{C}, \mathbf{D}$ or $\mathbf{E}$, are covalently bonded? [2]
(ii) Which one of these structures, $\mathbf{A}, \mathbf{B}, \mathbf{C}, \mathbf{D}$ or $\mathbf{E}$, is a diatomic molecule? [1]
(iii) Which one of these structures, $\mathbf{A}, \mathbf{B}, \mathbf{C}, \mathbf{D}$ or $\mathbf{E}$, is a compound? [1]
(iv) Which one of these structures, $\mathbf{A}, \mathbf{B}, \mathbf{C}, \mathbf{D}$ or $\mathbf{E}$, is very soluble in water? [1]
(v) Which one of these structures, $\mathbf{A}, \mathbf{B}, \mathbf{C}, \mathbf{D}$ or $\mathbf{E}$, is used in cutting tools? [1]
(vi) Which one of these structures, $\mathbf{A}, \mathbf{B}, \mathbf{C}, \mathbf{D}$ or $\mathbf{E}$, is used in electrical wiring? [1]
(b) Substance $\mathbf{B}$ is an element.
What is meant by the term element? [1] [Total: 8]
▶️Answer/Explanation
Ans:
(a)(i) B / diamond (1)
D / nitrogen / N2 (1)
(a)(ii) D / nitrogen / N2
(a)(iii) C / lithium chloride / LiCl
(a)(iv) C / lithium chloride / LiCl
(a)(v) B / diamond
(a)(vi) E / copper / Cu
(b) substance in which all the atoms have the same proton number / substance containing (only) one type of atom
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
(a) The electronic structures of five atoms, A, B, C, D and E, are shown.
Answer the following questions about these electronic structures.
Each electronic structure may be used once, more than once or not at all.
State which electronic structure, A, B, C, D or E, represents:
(i) an atom in Group II of the Periodic Table
(ii) an atom with a proton number of 13
(iii) an atom that forms a stable ion with a single negative charge
(iv) an atom of a non-metal that forms a giant covalent structure
(v) an atom of a metal used in food containers.
(b) Complete the table to show the number of electrons, neutrons and protons in the vanadium atom and calcium ion shown.
Answer/Explanation
Answer:
(a) (i) C
(ii) D
(iii) E
(iv) B
(v) D
(b) number of electrons in Ca ion: = 18 (1)
number of neutrons in V = 28 (1)
number of protons in V = 23
AND
number of protons in Ca ion = 20 (1)