(a) \u00a0 \u00a0 Graphite
\n– \u00a0 \u00a0 \u00a0 Black, soft, greasy
\n– \u00a0 \u00a0 \u00a0 Conducts electricity
\n– \u00a0 \u00a0 \u00a0 Most common form
\n– \u00a0 \u00a0 \u00a0 Used as lubricant, conductor in drycells and in pencil \u2018leads\u2019<\/p>\n
(b) \u00a0 \u00a0 Diamonds
\n– \u00a0 \u00a0 \u00a0 Transparent, hard
\n– \u00a0 \u00a0 \u00a0 Does not conduct electricity
\n– \u00a0 \u00a0 \u00a0 Uncommon
\n– \u00a0 \u00a0 \u00a0 Used in jewelry, blades<\/p>\n
Graphite With only 3 covalent bonds formed between carbon atoms within the\u00a0layers, an unbonded electron is present on each carbon atom. These\u00a0spare electrons form electron clouds between the layers and it is\u00a0because of these spare electrons that graphite conducts electricity.<\/p>\n Diamond These two examples of allotropes are important. You must be able to (a) \u00a0 \u00a0 Graphite – \u00a0 \u00a0 \u00a0 Black, soft, greasy – \u00a0 \u00a0 \u00a0 Conducts electricity – \u00a0 \u00a0 \u00a0 Most common form – \u00a0 \u00a0 \u00a0 Used as lubricant, conductor in drycells and in pencil \u2018leads\u2019 (b) \u00a0 \u00a0 Diamonds – \u00a0 \u00a0 \u00a0 Transparent, hard – \u00a0 \u00a0 \u00a0 Does not conduct … <\/p>\n
\nMake sure you know about the layer structure of graphite. Within each layer each\u00a0carbon atom is bonded to three others by strong covalent <\/span>bonds. Each\u00a0layer is therefore a giant molecule<\/span>. Between these layers there are\u00a0weak forces of attraction (=van der Waal’s forces) and so the layers\u00a0will pass over each other easily.<\/p>\n
\n<\/strong>You also need to know the structure of diamond. Each of the carbon atoms\u00a0in the giant structure is covalently bonded to four others. They form\u00a0a tetrahedral <\/span>arrangement. This bonding scheme gives rise to a very\u00a0rigid, three dimensional structure and accounts for the extreme\u00a0hardness of the substance. All the outer energy level electrons of the\u00a0carbon atoms are used to form covalent bonds, so there are no\u00a0electrons available to enable diamond to conduct electricity.<\/p>\n
\ngive account of differences.<\/p>\n","protected":false},"excerpt":{"rendered":"