Atomic Structure

Question 1

Describe our current nuclear model of the atom

Answer 1

• tiny nucleus
• contains protons and neutrons
• mostly empty space
• electrons are fixed on energy levels on the outside of the nucleus

Question 2

What is an isotope

Answer 2

An isotope of an element are atoms with a different number of neutrons but the same number of protons

Question 3

Which are the most ionising alpha particles or gamma

Answer 3

Alpha particles

Question 4

Outline why beta emitters rather than alpha or gamma emitters are used to test the thickness of sheets of metal

Answer 4

Beta emitters are not immediately absorbed like alpha radiation and do not penetrate as far as gamma therefore variations of the thickness of the sheet significantly affect the amount of radiation passing through beta radiation

Question 5

Name one type of nuclear radiation the particles of which are electrons

Answer 5

Beta

Question 6

Name the type of nuclear radiation that is an electromagnetic wave

Answer 6

Gamma

Question 7

What is the difference between radioactive contamination

Answer 7

Irradiation does not make something radio active
Contamination makes something radio active
Contamination is caused by direct contact
Irradiation is caused by background radiation

Question 8

Why is contamination by an alpha source more dangerous to humans than irradiation

Answer 8

Substances witch a short half life decay very quickly and emit high amounts of radiation which is highly ionising

Question 9

Briefly describe how the model of an atom has changed over time

Answer 9

• 1804 John Dalton thought matter was made up of tiny spheres
• 1900s J.J Thompson discovered particles called electrons he suggested atoms were spheres of positive charge with tiny negative electrons stuck in them (plum pudding)
• Rutherford conducted the Alpha scattering experiment in which he discovered there is a tiny positive charge which was the nucleus and that most of the atom is empty space
• Bohr discovered electrons orbit around the nucleus

Question 10

Who provided the evidence to suggest the existence to suggest the existence of the neutron

Answer 10

James Chadwick

Question 11

True or false atoms have no overall charge

Answer 11

True

Question 12

What happens to an atom if it loses one or more of its outer electrons

Answer 12

It becomes a positively charged ion

Question 13

Which number defines what an element an atom is: the atomic number or the mass number

Answer 13

Atomic number

Question 14

What is the atomic number

Answer 14

The number of protons

Question 15

True or false isotopes have different mass numbers

Answer 15

True