Atomic Structure

Question 1

Atoms are very small what is the radius of an atom

Answer 1

1×10^ -10 meters

Question 2

What is the basic structure of an atom

Answer 2

An atom is a positively charged nucleus with both protons and neutrons surrounded by negatively charged electrons

Question 3

Where is most of the mass of an atom concentrated in

Answer 3

Most of the mass of an atom is concentrated in the nucleus

Question 4

How are the electrons arranged from the nucleus

Answer 4

The electrons are arranged at different distances from the nucleus (Different energy levels)

The electron arrangements may change with the absorption of electromagnetic radiation (Move further from the nucleus; a higher energy level)

Or by the emission of electromagnetic radiation (Move closer to the nucleus; a lower energy level)

Question 5

In an atom the number of electrons is equal to the number of what

Answer 5

Protons in the nucleus

Question 6

Do atoms have a charge

Answer 6

Atoms have no overall electric charge

Question 7

The total number of protons and neutrons is called

Answer 7

The mass number

Question 8

All atoms of a particular element have the same number of protons. What is the number of protons called

Answer 8

Atomic number

Question 9

What can atoms turn into if they lose one or more outer electron

Answer 9

Atoms turn into positive ions

Question 10

Define isotope

Answer 10

An atom that has the same number of protons but a different number of neutrons.

Question 11

Before the discovery of the electron what were atoms thought to be

Answer 11

Atoms were thought to be tiny spears that could not be divided

Question 12

What did the discovery of the electron lead to

Answer 12

The plum pudding model of the atom

Question 13

What was the plum pudding model suggested to be

Answer 13

The plum pudding model suggested that the item is a ball of positivity charge with negative electrons embedded in it

Question 14

What model replace the plumbing pudding model

Answer 14

The nuclear model

Question 15

The results from the alpha particle experiment led to a conclusion of what

Answer 15

That the mass of an atom is concentrated at the center (nucleus) and the nucleus was charged

Question 16

What was Niels Bohrs theory 

Answer 16

That’s the electrons orbit the nucleus at a specific distance

Question 17

What did Letcher experiments lied to about the nucleus

Answer 17

That the positive charge of any nucleus could be subdivided into a whole number of smaller particles each particle having the same amount of positive charge. The name proton was given to these particles.

Question 18

The experimental work of James Chadwick led to the evidence of what

Answer 18

The evidence to show the existence of neutrons within the nucleus

Question 19

What does the nucleus give out

Answer 19

The nucleus gives out radiation as it changes to become more stable

this is called radioactive decay

Question 20

Define activity

Answer 20

Activity is the rate at which a source of unstable nuclei decays

Question 21

What is activity measured in

Answer 21

Becquerel (Bq)

Question 22

Define current rate

Answer 22

Count rate is the number of the keys recorded each second of a detector (E.g. Geiger-muller tube)

Question 23

What is an alpha particle

Answer 23

It consists of 2 neutrons and 2 protons its the same as helium nucleus

Question 24

What is a beta particle

Answer 24

A high-speed/fast moving electron emitted from the nucleus when a neutron turns into a proton and electron

Question 25

What is gamma ray

Answer 25

Electromagnetic radiation from the nucleus they have no mass or charge

Question 26

What are nuclear equations used for

Answer 26

Nuclear equations are used to represent radioactive decay

Question 27

What is radioactive contamination

Answer 27

Radioactive contamination is the unwanted presence of materials containing radioactive atoms on other materials

Question 28

What are the hazard for contamination

Answer 28

The hazard from contamination is due to the decay of the contaminating atoms (Ionizing radiation)

The type of radiation emitted affects the level of hazard.

Question 29

What is Irradiation

Answer 29

Irradiation is the process of exposing an object to nuclear radiation (Alpha, Beta, Gamma, neutrons.)

The irradiated object does not become radioactive.

Question 30

What is meant by ionising power

Answer 30

When radiation collides with atoms that can cause the atoms to lose electrons and form ions

Question 31

Alpha particles are what with ionizing power

Answer 31

Alpha particles: very strong ionizing but can be easily stopped by a dead cells on the skin surface.

Very dangerous if alpha is inhaled or swallowed

Question 32

Better particles are what with ionizing power

Answer 32

Butter particles: quite ionized but can penetrate skin into the Body

Question 33

Gamma radiation are what with ionizing power

Answer 33

Gamma radiation: weakly ionising but can penetrate (Go through matter) body but likely to pass straight through

Question 34

Define radioactive decay

Answer 34

Radioactive isotopes release radiation from the nucleus of their atoms

This cannot be predicted. Decay is a random process.

Question 35

Define half life

Answer 35

Half-life of a radioactive isotope is the time it takes for a number of nuclei of the isotope in a sample to halve

Question 36

What is the risk of ionizing radiation

Answer 36

It can increase the risk of cancer in humans

Question 37

How can alpha radiation be shielded from humans

Answer 37

By wearing gloves

Question 38

How can better and gamma radiation be shielded

Answer 38

It can be reduced using a lead apron

Question 39

What is meant by peer review

Answer 39

When scientists explore the effects of radiation and is shared with other scientists to be checked

Question 40

What is the difference between radioactive contamination and irradiation

Answer 40

Radioactive contamination occurs when there is a direct contact with radioactive substances

The radiation occurs when there is an indirect exposure to radioactive substances