C1 Particles

Question 1

Name three examples of particles in chemistry

Answer 1

Atoms, ions, molecules, compounds

Question 2

Describe the main difference between the arrangement of particles in the liquid state and particles in the gas state

Answer 2

Liquid:
Particles move around each other
Medium forces of attraction
Fixed volume
Gas:
Particles move freely
No forces of attraction
No fixed volume
No fixed shape

Question 3

Explain why you can compress a substance in the gas state

Answer 3

Since gas has no fixed volume, it can move freely and so will move into space

Question 4

Explain why a solid expands when it is heated

Answer 4

When a solid is heated, its forces of attraction begin to break down and it is able to move slightly, so the particles move away from each other

Question 5

What is a physical change?

Answer 5

A change of state that can (generally) easily be reversed. The arrangement and number of particles and atoms are not changed. No new products are made

Question 6

What is a chemical change?

Answer 6

A change that produces one or more new substances. Different particles react with each other to form different products. They are usually hard to reverse.

Question 7

What are the advantages of the particle model?

Answer 7

It shows the arrangement of the atoms in all three states of matter

Question 8

What are the disadvantages of the particle model?

Answer 8

The distance between the particles (in the gas state)
It does not show the forces/movement of particles
It is 2D when particles are 3D

Question 9

What keeps particles close together in liquids?

Answer 9

Electrostatic forces of attraction

Question 10

What is the charge and mass of a proton?

Answer 10

+1, 1

Question 11

What is the charge and mass of an electron?

Answer 11

-1, 0.0005

Question 12

What is the charge and mass of a neutron?

Answer 12

0,1

Question 13

Why is most of an atom’s mass in its nucleus?

Answer 13

The nucleus is where the protons and neutrons are, which weigh far more than the electrons orbiting it.

Question 14

How many times bigger is the radius of an atom compared to the radius of its radius?

Answer 14

100,000 times

Question 15

Describe the structure of an atom

Answer 15

A nucleus of protons and neutrons orbited by electrons in fixed electron shells.

Question 16

How many times greater is the mass of a proton compared to an electron?

Answer 16

2000 times

Question 17

What is an isotope?

Answer 17

Atoms of an element with the same number of protons and electrons but different numbers of neutrons

Question 18

Define atomic number

Answer 18

The number of protons in an element (and the number of electrons because they are the same)

Question 19

Define mass number

Answer 19

The total number of protons and neutrons in an atom

Question 20

Define ion

Answer 20

Ions are charged particles formed when atoms, or groups of atoms, lose or gain electrons during chemical reactions

Question 21

What was John Dalton’s theory about the atom?

Answer 21

Atoms were solid spheres with nothing in them

Question 22

What was the plum pudding model and who invented it?

Answer 22

The plum pudding model described an atom that was a large positive mass with electrons embedded within it like a pudding cake with plums in it. It was invented by J.J. Thomson

Question 23

What was Rutherford’s experiment?

Answer 23

Rutherford fired positively charged alpha particles at a thin sheet of gold foil (atoms).

Question 24

What was the expected result of Rutherford’s experiment?

Answer 24

Rutherford expected all the particles to pass straight through as there was not enough strong positive charge to deflect any of them.

Question 25

What actually happened in Rutherford’s experiment?

Answer 25

A few of the alpha particles deflected or came straight back, leading to the nuclear model of the atom

Question 26

What was the nuclear model of the atom?

Answer 26

A nucleus of protons surrounded by a cloud of electrons

Question 27

What was Bohr’s model?

Answer 27

Bohr’s model had the electrons orbiting the atom in electron shells so that they would not get attracted to the positively charged nucleus

Question 28

What did James Chadwick discover?

Answer 28

He discovered neutrons and their place in the nucleus