The arrangement of the particles
3 marks · EasyThe diagram below shows three beakers, each containing a different substance at room temperature.
State which beaker would represent water vapour. Give a reason for your answer.
Describe the arrangement of the particles in the beaker containing a liquid.
Explain why solids keep their shape, using the particle model.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Beaker with particles far apart (gas) represents water vapour; because particles in a gas are far apart and move freely.
(b) Particles are close together but not in a regular arrangement; they can move past each other.
(c) Because the particles are in a fixed, regular arrangement and can only vibrate in place.
Common mistakes: Mixing up states or arrangements
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies Beaker representing gas as water vapour and gives a correct reason based on particle arrangement or motion.
B2 (b) · 1 mark · States that particles in a liquid are close together but not in regular pattern/can move past each other.
B3 (c) · 1 mark · Explains solid shape by stating particles are in a fixed, regular arrangement/only vibrate.
Worked solution
a) Beaker representing water vapour is the one with particles far apart, because in gases, particles are spaced out and move freely.
b) In a liquid, particles are close together but are not arranged in a regular pattern; they can move past each other.
c) Solids keep their shape because their particles are held in a fixed, regular arrangement and can only vibrate about fixed positions.