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Structures

use the accepted structural model for giant ionic lattices to explain the physical properties of ionic substances such as sodium chloride, including melting point, boiling point and electrical conductivity (drawing a diagram of a giant ionic lattice is not expected but students should be able to recognise it);
recall that most ionic compounds are soluble in water;

use the accepted structural model for molecular covalent structures to explain the physical properties of molecular covalent structures such as iodine and carbon dioxide, including melting point, boiling point and electrical conductivity;
demonstrate knowledge and understanding that the intermolecular forces between covalent molecules are weak forces called van der Waals' forces;
recall that many covalent molecular substances are insoluble in water;

demonstrate knowledge and understanding of the giant covalent structure of carbon (diamond) and carbon (graphite), and predict and explain their physical properties, including:
•    electrical conductivity;
•    hardness;
•    melting point and boiling point; and
•    their uses in cutting tools (diamond), lubricants and pencils (graphite); and
use the accepted structural model for metals to predict and explain their structure and physical properties including melting point, malleability, ductility and electrical conductivity.
 

use the accepted structural model for metals to predict and explain their structure and physical properties including melting point, malleability, ductility and electrical conductivity.

demonstrate knowledge and understanding that an alloy is a mixture of two or more elements, at least one of which is a metal, and the resulting mixture has metallic properties;
demonstrate knowledge and understanding that the different sizes of atoms in an alloy distort the layers in the metallic structure, making it more difficult for them to slide over each other, and so alloys are harder than pure metals;
recall that gold used in jewellery is usually an alloy with silver, copper and zinc, that the proportion of gold is measured in carats, and that 24 carat gold indicates pure gold and 18 carat gold indicates 75% gold;

demonstrate knowledge and understanding that carbon can form four covalent bonds;! demonstrate knowledge and understanding of the structure of graphene (a single atom thick layer of graphite), explain its physical properties, including strength and electrical conductivity, and recall its uses such as those in batteries and solar cells;I demonstrate knowledge and understanding of the meaning of the term allotrope as applied to carbon (diamond), carbon (graphite) and graphene;

use given information to classify the structure of substances as giant ionic lattice, molecular covalent, giant covalent or metallic.

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