Name:.............................................................................
C2.4 Revision - 17 Questions
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Give the electron configuration of a carbon atom (1)
Copy and complete the dot-cross diagram of water by adding the electrons of the hydrogen atoms
(1)
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Draw a dot-cross diagram to show the bonding within a molecule of methane (CH4) (2)
State what is meant by a covalent bond? (1)
List three simple molecular covalent substances (3)
Explain why most simple covalent substances have low melting and boiling points? (2)
Give the name of a giant molecular covalent substance (1)
Explain why giant molecular covalent substances have high melting and boiling points (2)
H: Compare the structures of diamond and graphite (4)
H: Explain why diamond is used for cutting tools (3)
H: Explain why graphite is used as a lubricant (3)
State what is meant by immiscible liquids (1)
Describe how oil and water could be separated (3)
Explain how to separate nitrogen and oxygen from the air (4)
A colouring in some sweets was analysed using paper chromatography. One of the dyes in the
colouring moved 2 cm up the paper while the solvent moved 8 cm. Calculate the Rf value of this dye
(2)
Look at the chromatogram to the right. State the letter
of the ink that contained only one coloured dye. (1)
Ink W has been made by mixing two of the other inks
together. State the two inks that could have been
mixed to make ink W. (1)
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What do you need to revise/learn/ask Miss Elliott about?
C2.3 Revision – 20 Answers!
1. 2.4
2. One dot added to each overlap between the hydrogen atom and the oxygen atom (1)
3. Outer shell of carbon showing 4 shared pairs of electrons with hydrogen atoms (1). No other
electrons on outer shell of carbon atom or hydrogen atoms (1)
4. A shared pair of electrons between two atoms. (1)
5. Any three from: hydrogen, methane, oxygen, carbon dioxide, water (or any other valid answer). (1
mark for each correct substance)
6. There are only weak forces of attraction between the molecules (1) (therefore) no much energy is
required to break these forces (1)
7. Any one from: Diamond, graphite, sand (silicon dioxide) (1)
8. Giant substances are made from billions of strongly bonded atoms (1) (therefore) a lot of energy is
required to break these bonds (1)
9. Any four from the following, with at least one from similarities and differences:
Similarities: Both are giant molecular covalent substances (1), both are made of carbon atoms
(covalently bonded together) (1), both have high melting and boiling points (1)
Differences: Each carbon in diamond is (covalently) bonded to four others (1), each carbon atom in
graphite is (covalently) bonded to three others (1), diamond is very hard (1), graphite is formed in
layers (1), each carbon atom in graphite has a free electron (1), diamond does not conduct
electricity (1), graphite conducts electricity (1).
10. Any three from: Diamond is a typical giant molecular covalent substance (1). It is made from
billions of atoms strongly bonded together (1) which makes it very hard (1). A lot of energy is
required to break it down (1) so it will not melt (with the high levels of friction) (1)
11. Any three from: Graphite is an atypical giant molecular covalent substance (1). Each atom is only
bonded to three others (1) (so) it forms in layers (1) which are held together with weak forces of
attraction (1). The layers easily rub off (1) (making it suitable for use as a lubricant).
12. Two liquids that do not mix together. (1)
13. Any three from: Put the oil and water into a separating funnel (1). The oil and water are immiscible
so form layers (1). Open the tap and drain off the bottom layer (water) into a beaker (1). Close the
tap and swap the beaker (1) then drain the top layer (oil) into the beaker (1).
14. Any four from: Use fractional distillation (1). Cool the air (to liquefy it) (1). Pass the liquid air into
a fractionating column (1) where it warms up (1). Oxygen is removed as a liquid (1) from the
bottom of the column (1). Nitrogen is removed as a gas (1) from the top of the column (1)
15. (spot moved) 2 / solvent (moved) 8 (1) Rf = 2/8 (1) (Rf = 0.25)
16. Ink Y (1)
17. Ink Y and ink Z (1)