AQA GCSE Chemistry (8462), Higher tier · Atomic structure and the periodic table › Properties of transition metals
Practise Comparison with Group 1 elements. 12 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
(d)Answer: Iron is strong and hard and does not react quickly with water or oxygen; sodium is soft and reacts vigorously with water.
iron is strong / hard
iron has a high melting point
iron does not react quickly with water / oxygen
sodium is soft / reacts (vigorously) with water / oxygen
Question 3Hard3 marks
Iron melts at 1538 °C. Sodium melts at 98 °C. In solid iron, each atom contributes two or three electrons to the delocalised electrons. In solid sodium, each atom contributes one electron.
Use this information and your knowledge of metallic bonding to explain why iron has a much higher melting point than sodium.[3]
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Answer: Iron has more delocalised electrons per atom and more highly charged positive ions, so the electrostatic attraction between the ions and the delocalised electrons is stronger; more energy is needed to overcome it.
iron has more delocalised electrons per atom / iron ions have a higher charge (2+ or 3+ compared with 1+)
so there is a stronger electrostatic attraction between the positive ions and the delocalised electrons (stronger metallic bonding)
so more energy is needed to overcome the metallic bonding when iron melts