A technician at a water-treatment works checks a sample of sodium chloride before it is added to a salt solution. Fig. 1 is a particle diagram for sodium ch...
Question 1 Report
A technician at a water-treatment works checks a sample of sodium chloride before it is added to a salt solution. Fig. 1 is a particle diagram for sodium chloride. The circles are not drawn to scale. Sodium atoms form positive ions and chlorine atoms form negative ions. The technician needs to explain why this compound is not made of separate sodium chloride molecules.
(a) Name the type of bonding in sodium chloride. [1]
(b) Describe how a sodium atom becomes a sodium ion. [2]
(c) Explain why the ions in Fig. 1 stay together in a solid crystal. [2]
A research team examines a rock collected near a volcanic vent. Fig. 1 shows the simplified atomic structure of an atom of potassium found in the rock. The nucleus contains particles A and B. Potassium can form an ionic compound with chloride ions in mineral water. The team wants to identify which particle gives the atom its atomic number.
(a) Name particle A if it has a positive charge. [1]
(b) What is the charge of particle B if it is a neutron? [1]
(c) Explain why a potassium ion has a different number of electrons from a potassium atom. [2]
Answer Details
Sodium chloride structure
(a) Sodium chloride has ionic bonding. [1]
(b) A sodium atom loses one electron [1], producing a positive \(\mathrm{Na^+}\) ion. [1]
(c) The solid crystal is held together by electrostatic attraction [1] between oppositely charged sodium and chloride ions. [1]
Potassium atom
(a) A positively charged particle in the nucleus is a proton. [1]
(b) A neutron has no charge, so it is neutral. [1]
(c) A potassium atom loses an electron [1] to form a positive potassium ion. [1]
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