An ion of aluminium can be written as $^{27}_{13}\text{Al}^{3+}$.
(a) Complete the table to show the relative mass and relative charge of a neutron and an electron. [2]
| Particle | Relative mass | Relative charge |
|---|---|---|
| proton | 1 | +1 |
| neutron | ||
| electron |
(b) State the number of protons, neutrons and electrons in this aluminium ion. [2]
- (a) neutron: relative mass 1 and relative charge 0(1)
- (a) electron: relative mass 1/1840 (accept 1/1836, 1/2000, 0.0005, negligible, almost zero) and relative charge −1 (accept −)(1)
- (b) 13 protons and 14 neutrons(1)
- (b) 10 electrons(1)
- Answer: neutron 1, 0; electron 1/1840, −1; 13 protons, 14 neutrons, 10 electrons
- Examiner tip: A 3+ ion has LOST three electrons — students often add them or forget to change the electron number at all.