Principles of Chemistry
7 marks · EasyThe following question is about atoms' subatomic particles and classification in the Periodic Table.
Nickel (Ni) has atomic number 28 and mass number 59. Calculate the number of protons, neutrons, and electrons in a neutral atom of nickel.
Using your answer to part (a) and the position of nickel in the Periodic Table, decide whether nickel is a metal or a non-metal. Explain your reasoning.
Tin (Sn) forms an oxide with the formula SnO2. Predict the acid-base character (acidic/basic/amphoteric) of this oxide and justify your answer based on tin's position in the Periodic Table.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Protons: 28; Neutrons: 59-28=31; Electrons: 28 (neutral atom).
(b) Nickel is a metal. It is on the left side (transition metals block) of the Periodic Table. Metals are found on the left and centre.
(c) Tin oxide (SnO2) is basic or amphoteric. Most metal oxides are basic, but some, like SnO2, can behave as amphoteric. Accept either with justification based on tin being a metal.
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Marking points
B1 (a) · 1 mark · Correct number of protons: 28.
B2 (a) · 1 mark · Correct calculation of neutrons: 59 - 28 = 31.
B3 (a) · 1 mark · Correct number of electrons: 28 (neutral atom).
B4 (b) · 1 mark · States that nickel is a metal.
B5 (b) · 1 mark · Reason based on position on Table: left or centre, or 'transition metal'.
B6 (c) · 1 mark · Identifies tin oxide as basic or amphoteric (accept either).
B7 (c) · 1 mark · Justifies answer using tin's metallic character/position in Periodic Table.
Worked solution
a) Protons = atomic number = 28. Neutrons = mass number - atomic number = 59 - 28 = 31. Electrons = protons (neutral atom) = 28.
b) Nickel is a metal because it is located among the transition metals, left of the midline in the Periodic Table.
c) Tin is a metal; the oxides of metals are usually basic. SnO2 can also be amphoteric (reacting with both acids and bases), which is typical for some metals like tin, but classifying it as basic is correct at this level.