A neutral atom of sodium is represented by 1123Na{}^{23}_{11}\mathrm{Na}1123Na.
Give the number of electrons in this atom.
The sodium atom loses one electron and becomes an ion.
Explain why the ion has a positive charge.
State the relative charge of the ion.
Explain why the electron lost is an outer electron and not an electron close to the nucleus.
A student says:
'When the sodium atom becomes an ion, its mass number changes from 23 to 22.'
Explain why the student is wrong.
103 exam-style questions on Edexcel GCSE Physics 6.1 Atomic structure and isotopes, covering 6.1.1 Structure of the atom, 6.1.2 Isotopes: atomic and mass number, 6.1.3 Sub-atomic particles: masses and charges, and 6.1.4 Electron orbits and energy changes. Each one has a worked solution and a mark scheme showing where the marks go.