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Question 1

Describe the plum pudding model of the atom

Answer 1

a ball of positive charge with negative electrons embedded in it

Question 2

Tennessine was first identified by a small group of scientists in 2010.
Suggest one reason why tennessine was not accepted as a new element by other
scientists until 2015.

Answer 2

time needed for peer review

Question 3

Methane is a gas at room temperature but poly(ethene) is a solid at room
temperature. Explain why methane and poly(ethene) exist in different states at room temperature.

Answer 3

methane has smaller
molecules. so has weaker intermolecular
forces. so the intermolecular forces
need less energy to overcome. so the boiling / melting point is
lower and methane is a gas

Question 4

Which element has atoms that have the same electronic structure as the chloride ion?

Answer 4

argon

Question 5

A solution of hydrochloric acid with pH 4.5 has a concentration of H+ ions of
3.16 × 10^−5 mol/dm3.
What is the concentration of H+ ions in a solution of hydrochloric acid with pH 2.5?

Answer 5

3.16 x 10^-3

Question 6

Describe how metals conduct electricity (3)

Answer 6

metals have delocalised
electrons. the electrons carry charge. the electrons move through the
structure / metal

Question 7

Explain how oxygen was produced from water during the electrolysis of an unknown aqueous solution

Answer 7

water breaks down to produce H+ and OH− ions. so OH− ions are attracted /
move to the positive electrode, where OH− ions are discharged / oxidised to give
oxygen

Question 8

Suggest why alloys do not conduct electricity as well as pure metals.

Answer 8

in alloys different sized atoms
distort the layers. so the movement of delocalised electrons are
restricted

Question 9

Argon has the atomic number 18
Explain why argon does not form compounds.

Answer 9

argon has a stable
arrangement of electrons.
so argon atoms do not share
or transfer electrons

Question 10

Suggest two observations that could be made when barium reacts with
hydrochloric acid.

Answer 10

• effervescence / fizzing /
  bubbles
• barium disappears
• forms a colourless solution
• temperature increases
  ignore references to floating /
  flames

Question 11

Nanoparticles of titanium dioxide are used instead of fine particles of titanium dioxide
for coating self-cleaning windows.
Suggest two reasons why.

Answer 11

• have a higher surface area to
  volume ratio
• less material needed for the
  same effect
• more light gets through