Topic 4: Atomic Structure

Question 1

Activity:

Answer 1

The rate at which an unstable nucleus decays.

Question 2

Alpha Particle:

Answer 2

A positively charged particle consisting of two protons and two neutrons.

Question 3

Atomic Number:

Answer 3

The number of protons found in an atom of a specific element. Each element has a different atomic number.

Question 4

*Background Radiation:

Answer 4

Radiation that is found in small quantities all around us and originates from natural sources such as rocks and cosmic rays, as well as from man-made sources such as nuclear weapons testing and accidents.

Question 5

Becquerel:

Answer 5

The unit of radioactive activity.

Question 6

Beta Particle:

Answer 6

A high speed electron that a nucleus emits when a neutron converts into a proton.

Question 7

Bohr Model:

Answer 7

A model of the atom that suggested that electrons orbit the nucleus at set distances.

Question 8

*Chain Reaction:

Answer 8

The process of neutrons released by a fission reaction, being absorbed by another unstable, large nuclei, and inducing further fission.

Question 9

Count-Rate:

Answer 9

The number of decays that a detector measures per second.

Question 10

Electrons:

Answer 10

A negatively charged constituent of the atom, that are found in different energy levels, around the nucleus.

Question 11

Energy Levels:

Answer 11

The stable states in which electrons are found in around a nucleus. Electrons can transition to a higher energy level through the absorption of electromagnetic radiation and can transition to a lower energy level through the emission of electromagnetic radiation.

Question 12

*Fission Products:

Answer 12

Fission produces two smaller nuclei, two or three neutrons and gamma rays. All these products are released with kinetic energy.

Question 13

Gamma Ray:

Answer 13

Electromagnetic radiation emitted from a nucleus.

Question 14

Geiger-Muller Tube:

Answer 14

A detector that measures the count-rate of a radioactive sample.

Question 15

Half-Life:

Answer 15

The time it takes for the number of unstable nuclei of an isotope in a sample to halve, or the time it takes for the initial count rate of a sample of the isotope to halve.

Question 16

Ions:

Answer 16

Atoms with a resultant charge due to the loss or gain of electrons.

Question 17

Irradiation:

Answer 17

The process of an object being exposed to nuclear radiation. The object doesn’t become radioactive.

Question 18

Isotopes:

Answer 18

Atoms with the same number of protons but different numbers of neutrons. The atomic number is the same, but the mass number is different.

Question 19

Mass Number:

Answer 19

The number of protons and neutrons in an atom.

Question 20

Negative Ions:

Answer 20

Atoms that gained electrons and so have a resultant negative charge.

Question 21

Neutrons:

Answer 21

A neutrally charged constituent of the nucleus.

Question 22

*Nuclear Explosions:

Answer 22

Nuclear explosions in nuclear weapons are caused by an uncontrolled chain reaction which results in vast quantities of energy being produced in a very small period of time.

Question 23

*Nuclear Fission:

Answer 23

The splitting of a large and unstable nucleus into two smaller and more stable nuclei to produce energy.

Question 24

*Nuclear Fusion:

Answer 24

The joining of two small, light nuclei to form a larger, heavier one and release energy.

Question 25

Nucleus:

Answer 25

The positively charged centre of an atom, containing protons and neutrons.

Question 26

Plum Pudding Model:

Answer 26

An old model of the atom that represented the atom as a ball of positive charge, with negative charges distributed throughout it.

Question 27

Positive Ions:

Answer 27

Atoms that have lost electrons and so have a resultant positive charge.

Question 28

Protons:

Answer 28

A positively charged constituent of the nucleus.

Question 29

Radioactive Contamination:

Answer 29

The unwanted presence of radioactive atoms on other materials. It is hazardous due to the decay of the contaminating atoms.

Question 30

Radioactive Decay:

Answer 30

The random process involving unstable nuclei emitting radiation to become more stable.

Question 31

*Sieverts:

Answer 31

The unit used for radiation dosage.

Question 32

*Spontaneous Fission:

Answer 32

Fission that occurs without the absorption of a neutron. Spontaneous fission is rare and in most cases, fission is induced with a neutron.