The term species is sometimes used to refer to neutral atoms and to positive and negative ions.
The table below shows the numbers of subatomic particles in eight different species, labelled A to H:
| Species | Number of protons | Number of neutrons | Number of electrons |
|---|---|---|---|
| A | 5 | 5 | 5 |
| B | 5 | 6 | 5 |
| C | 6 | 6 | 4 |
| D | 8 | 8 | 8 |
| E | 9 | 10 | 9 |
| F | 11 | 12 | 10 |
| G | 17 | 18 | 18 |
| H | 17 | 20 | 18 |
(i) Explain which two letters represent neutral atoms of the same element.
(ii) Explain which two letters represent negative ions formed from the same element.
(iii) Explain which letter represents the species with the lowest mass number.
(iv) What is the electronic configuration of species D?
The table below shows the percentage composition of a sample of magnesium.
| Isotope | 24Mg^{24}\text{Mg}24Mg | 25Mg^{25}\text{Mg}25Mg | 26Mg^{26}\text{Mg}26Mg |
|---|---|---|---|
| Percentage (%) | 78.8 | 10.1 | 11.1 |
Calculate the relative atomic mass of this sample of magnesium. Give your answer to one decimal place.
41 exam-style questions on Edexcel IGCSE Chemistry Atomic structure. Each one has a worked solution and a mark scheme showing where the marks go.