Paper 2 · Subatomic particles, ions and bonding
Which statement correctly describes a difference between a chlorine atom, Cl, and a chloride ion, Cl⁻?
AThe chloride ion has one more electron than the chlorine atom, giving it a negative charge.
BThe chloride ion has one fewer electron than the chlorine atom, giving it a positive charge.
CThe chloride ion has one more proton than the chlorine atom.
DThe chloride ion has one more neutron than the chlorine atom.
Explanation: A chloride ion forms when a chlorine atom gains one electron, giving it one more electron than protons and hence a single negative charge. The number of protons and neutrons is unchanged.
Derived from ZIMSEC Chemistry 5071/2 Paper 2 Theory, November 2014, Q1
