A-LevelChemistryAtomic structure9701/22 · May/June 2017 · Q16 Marks

The composition of atoms and ions can be determined from knowledge of atomic number, nucleon number and charge.

(a)Complete the table. atomic number | nucleon number | number of electrons | number of protons | number of neutrons | symbol ---|---|---|---|---|--- 3 | | 2 | | | ⁶Li⁺ | | | | 32 | | | 23 | 26 | | |[2]
(b)(i)Define the term relative isotopic mass.[2]
(b)(ii)Calculate the relative isotopic mass of ¹¹B. Give your answer to six significant figures. Show your working.[2]

Mark scheme

Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.

[1] First row: nucleon number 6, number of protons 3, number of neutrons 3
[1] Second row: atomic number 26, symbol ⁵⁸Fe³⁺
[1] mass of an atom / isotope
[1] relative / compared to 1/12 (the mass) of (an atom of) C-12 OR on a scale in which a C-12 (atom / isotope) has (a mass of exactly) 12 (units)
[1] mass of one mol (of atoms) of an isotope
[1] relative / compared to 1/12 (the mass) of 1 mol of C-12 OR on a scale in which one mol C-12 (atom / isotope) has a mass of (exactly) 12 g
[1] (10.0129 × 19.78) + (80.22x) = 10.8 / 100
[1] x = 10.9941

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