C1 - Particles

Question 1

What constitutes as a particle?

Answer 1

• Atoms
• Ions
• Molecules

Question 2

What are the properties of a solid?

Answer 2

• Regular lattice particle arrangement
• Particles are very close
• Particles vibrate about fixed positions

Question 3

What are the properties of a liquid?

Answer 3

• Random particle arrangement
• Particles are close together with some gaps
• Particles move around each other

Question 4

What are the properties of a gas?

Answer 4

• Random particle arrangement
• Particles are far apart
• Particles move quickly in all direction

Question 5

In which state(s) can something not be compressed?

Answer 5

A substance in solid/liquid state cannot be compressed because there is no space for particles to move into.

Question 6

Why can substances in the solid state not flow?

Answer 6

A solid substance cannot flow as it has a fixed shape. Particles vibrate about fixed positions and do not move.

Question 7

Why do solids expand when heated?

Answer 7

When heated, particles in a solid gain kinetic energy and vibrate more. The space between the particles increase as a result, making the solid ‘expand’.

Question 8

What is a Physical change?

Answer 8

A reversible change that doesn’t result in a new substance being formed.

Question 9

What happens to the particles in a physical change?

Answer 9

During a physical change, the arrangement and movement of the particles change.

Question 10

What is a Chemical change?

Answer 10

An irreversible change where new substances are formed.

Question 11

What happens to the particles in a physical change?

Answer 11

During a chemical change, particles break their bonds and join in different ways, resulting in new substances to be formed.

Question 12

What are the limitations of the particles model?

Answer 12

These three things are not taken into account:
- The forces between particles.
- The size of particles.
- The space between particles.

Question 13

Define ‘molecule’.

Answer 13

Two or more atoms chemically joined together.

Question 14

What are the relative atomic masses of:
Protons, Neutrons and Electrons.

Answer 14

Protons - 1
Neutrons - 1
Electrons - 0.0005 (1/2000)

Question 15

What are the relative atomic charges of:
Protons, Neutrons and Electrons.

Answer 15

Protons: +1
Neutrons: 0
Electrons: -1

Question 16

Define ‘isotope’.

Answer 16

A different atomic form of an element where atoms of an element have the same number of protons and electrons, but a different number of neutrons.

Question 17

Order Of Scientists - Developing the Atomic Model

Answer 17

1. John Dalton - 1803
2. JJ Thomson - 1897
3. Ernest Rutherford - 1909
4. Niels Bohr - 1913

Question 18

What did Dalton suggest?

Answer 18

• All matter is made from atoms.
• All atoms of an element are identical.
• Different elements have different types of atoms.
• Tiny solid balls.

Question 19

What did Thomson do?

Answer 19

• Development of the ‘Plum Pudding Model’.
• Shot beams of ‘cathode rays’ - their direction changed in electric/magnetic fields.
• Concluded atoms are spheres of positive charge, scattered with elections.
• Atoms are overall neutral.

Question 20

What did Rutherford do?

Answer 20

• Gold foil experiment, fired beams of positively charged alpha particles at thin sheets of gold.
• Contrary to what should’ve happened (particles go straight through), many were deflected.
• A positively charged mass in the centre of the nucleus (called nucleus)
• Electrons orbit the nucleus like planets do the sun.

Question 21

What did Bohr do?

Answer 21

• He realised that orbiting electrons would be attracted to the oppositely charged nucleus, collapsing the atom.
• Bohr suggested electrons occupied fixed energy levels (electron shells), around the nucleus.