4.4 Atomic Structure

Question 1

What is radius of an atom?

Answer 1

1x10 to the power of -10

Question 2

What is the basic structure of an atom?

Answer 2

A positively charged nucleus containing protons and neutrons surrounded by negatively charged electrons

Question 3

Where is the mass of an atom concentrated?

Answer 3

In the nucleus

Question 4

How does the electron arrangements change?

Answer 4

With the absorption of electromagnetic radiation ( move further from the nucleus ; a higher energy level or by the emissions electromagnetic magnet radiation ( move closer to the nucleus; a lower energy level

Question 5

What charge do atoms have?

Answer 5

No overall charge

Question 6

What is the number of protons in an atom equal to?

Answer 6

The number of electrons

Question 7

What is the number of protons in an atoms called?

Answer 7

Atomic number

Question 8

What is the mass number?

Answer 8

The total number of protons and neutrons in an atom

Question 9

What are isotopes?

Answer 9

The same element that has the same number of protons but different number of neutrons

Question 10

What happens to atoms if the lose an electron?

Answer 10

They become a positive ion

Question 11

What did the plum pudding model suggest?

Answer 11

An atom is a ball of positivity with negative electrons embedded in it

Question 12

What did the result of the alpha particle scattering model lead to?

Answer 12

Mass of an atom was concentrated at the centre and that the nucleus was charged also that an atom was mostly made up of air

Question 13

How did night bor adapt the nuclear model?

Answer 13

By suggesting that the electrons orbit the nucleus at specific distances

Question 14

What did later experiments show?

Answer 14

That the positive charge of any nucleus could be subdivided into a whole number of smaller particles the name proton was given to these

Question 15

What James Chadwick show?

Answer 15

Provided the evidence to show the existence of neutrons within the nucleus

Question 16

What is radio active decay?

Answer 16

Some nuclei are unstable the nucleus gives out radiation as it changes to become more stabel

Question 17

What is activity?

Answer 17

The rate at which a source of unstable nuclei decays and is measured in becquerel

Question 18

What is count rate?

Answer 18

The number of decays recorded each second by a detector

Question 19

What is an alpha particle scattering?

Answer 19

This consists of two neutrons and two protons it is the same as a helium nucleus

Question 20

What is a beta particle?

Answer 20

A high speed electron ejected from the nucleus as a neutron turns into a proton

Question 21

What is a gamma ray?

Answer 21

Electromagnetic radiation from the nucleus a neutron

Question 22

What is used to represent radioactive decay?

Answer 22

Nuclear equations

Question 23

What does beta decay do?

Answer 23

It does not cause the mass of the nucleus to change but does cause the charge of the nucleus to increase

Question 24

What does the emissions of gamma ray do?

Answer 24

Does not cause the mass or the charge of the nucleus to change

Question 25

Is radioactive decay random?

Answer 25

Yes

Question 26

What is the half life of radio active isotope?

Answer 26

The time it takes for the number of nuclei of the isotopes in a sample to half or the time it takes for the count rate from a sample containing the isotopes to fall to half its initial level

Question 27

What is radioactive contamination?

Answer 27

The unwanted presence of materials containing radioactive atoms on other mater

Question 28

What is the hazard from radioactive contamination due to?

Answer 28

The decay of contaminating atoms

Question 29

What affects the level of hazards?

Answer 29

The type of radiation emitted

Question 30

What is irradiation?

Answer 30

The process of exposing an object to nuclear radiation the irradiated object does not become radioactive

Question 31

What does background radiation come from?

Answer 31

Natural sources such as rocks and cosmic rays from space Man jaded sources such as the fallout from nuclear weapons testing and nuclear accidents

Question 32

What is radiation dose measured in?

Answer 32

Sieverts 1000 millisieverts = 1 sieverts

Question 33

What do radiation isotopes have?

Answer 33

A wide range of half life values

Question 34

What are nucleur radiation used in?

Answer 34

Medicine of the exploration of internal organs Control or destruction of unwanted tissue

Question 35

What is nuclear fission ?

Answer 35

The splitting of a large and unstable nucleus

Question 36

How does fission occur?

Answer 36

The unstable nucleus must first absorb a neutron

Question 37

What happens in nuclear fission?

Answer 37

The nucleus splits into two smaller nuclei roughly equal in size and emits two or three neutrons plus gamma rays . Energy is released by the fission reaction

Question 38

What do all of the fission products have?

Answer 38

Kinetic energy

Question 39

What doe the neutrons from nuclear fission start?

Answer 39

A chain reaction

Question 40

What is the chain react controlled in?

Answer 40

A nuclear reactor to control the energy released

Question 41

What is the explosion caused by a nuclear weapon caused by ?

Answer 41

An uncontrollable chain reaction

Question 42

What is nuclear fusion?

Answer 42

The joining of two light nuclei to form a heavier nucleus.

Question 43

What happens during nuclear fusion?

Answer 43

Some of the mass may be converted into the energy radiation

Question 44

What is alpha radiation stopped by?

Answer 44

Paper and had a range of few centimetres in air

Question 45

What does alpha particle consist of?

Answer 45

2 protons and 2 neutrons

Question 46

What do alpha particles have?

Answer 46

The greatest ionising power

Question 47

What is beta radiation stopped by?

Answer 47

A thin sheet of metal and has a range of about one metre in air

Question 48

What does beta radiation consist of?

Answer 48

Fast moving electrons emitted from the nucleus

Question 49

How ionising is beta radiation?

Answer 49

Less ionising than alpha radiation and more ionising than gamma radiation

Question 50

What is gamma radiation stopped by?

Answer 50

Thick lead and has an unlimited range in air

Question 51

What does gamma radiation consist of?

Answer 51

Electromagnetic radiation and has is the least ionising

Question 52

What can alpha beta and gamma radiation ionise?

Answer 52

Substances they pass through ionisation in a living cell can damage or kill the cell