Unit 7

Question 1

Conductors

Answer 1

Substances which conduct electricity but are not chemically changed during electrical conduction.
(Requires mobile ions / mobile electrons)
(eg. Copper and Magnesium)

Question 2

Electrolytes

Answer 2

Substances which conduct electricity in molten state or aqueous solution but not in solid state, and are decomposed during the conduction.
(Molten liquid / aqueous solution)
(Compounds of non-metals and metals: eg. sodium chloride, potassium oxide)

Question 3

Non-conductors

Answer 3

Substances which do not conduct electricity in solid, liquid or aqueous state
(Compounds made up from non-metals ONLY)
(Eg. Chlorine, sulphur, ethanol (H, C, O), candle wax (C, H))

Question 4

Chemical bond

Answer 4

Th electrostatic attraction/force between 2 particles

Question 5

Ionic bond

Answer 5

DEFINITION: The strong electrostatic forces of attraction between oppositely charged ions
-It is formed when electron(s) is/are transferred from one atom (or group of atoms) to another (or group of atoms).

ionic compound
-when a metal and a non-metal combine to form an ionic compound, electrons are transferred from atoms of the metal to atoms of the non-metal.

-ions are packed together and a regular arrangement called the lattice

Non-directional —> every ion is attracted to every other ion with opposite charge

Question 6

Migration of permanganate ions

Answer 6

Steps:
1. Place a small crystal of potassium permanganate at the centre of a strip of filter paper moistened with sodium sulphate solution.
2. Apply a direct current across the filter paper.
3. A purple spot moves slowly towards clip X that is connected to the positive terminal of the power supply. (Because the negative permanganate ions migrate towards clip X that is connected to the positive terminal.

sodium sulphate solution is an electrolyte so that the result will not be affected but it can conduct electricity.

Question 7

Metallic bonding

Answer 7

DEFINITION: the strong electrostatic forces of attraction between the positive metal ions and a “sea” of delocalised electrons

Atoms in a metal are packed closely together in layers
Metals —> 1 to 3 electrons in their outermost electron shell, they are lost and become free to move randomly throughout the metal. These electrons are said to be delocalised

Having lost the outermost shell electrons, the metal atoms become positive ions —> fixed in position and arranged in a regular way

regular three-dimensional arrangement of magnesium ions surrounded by a “sea” of delocalised electrons

non-directional