atomic structure

Question 1

what is the radius of an atom?

Answer 1

1x10(-10) metres

Question 2

what does an atom contain?

Answer 2

An atom contains:

• positive nucleus which is made up of protons and neutrons
• > it is surrounded by negatively charged electrons

Question 3

what is the protons electrical charge?

Answer 3

a protons electrical charge is:

+1

Question 4

what is an electrons electrical charge?

Answer 4

an electrons electrical charge is:

-1

Question 5

why does an atom have no overall electrical charge?

Answer 5

Atoms have no overall electrical charge because they have equal numbers of electrons and protons

Question 6

what is most of the atoms mass?

Answer 6

nucleus

Question 7

what is the nucleus radius of an atom?

Answer 7

1
———
1000

Question 8

If an atom loses one outer electron, what does it become?

Answer 8

positive ion

Question 9

If an atom gains one extra electron, what does it become?

Answer 9

negative ion

Question 10

all atoms of a particular element have the same number of….

Answer 10

protons

Question 11

what is the atomic number?

Answer 11

The atomic number is the number of protons in an atom of an element

Question 12

what is the mass number?

Answer 12

the mass number is the total number of protons and neutrons in an atom

Question 13

isotopes

Answer 13

isotopes are atoms of the same element that have different number of neutrons

Question 14

isotopes have

Answer 14

• same number of proton

- different number of neutron

Question 15

what would happen if the proton number changed?

Answer 15

they would be a different element

Question 16

what were atoms thought as?

Answer 16

people thought that atoms were unable to split

Question 17

what was the plum pudding model?

Answer 17

The plum pudding model was a model of negative electrons in positive charge
-positives would cancel out negatives

Question 18

what happens if an atomic nuclei is unstable?

Answer 18

if an atomic nuclei is unstable they give out radiation in order to become more stable

Question 19

what does the type of radiation depend on?

Answer 19

The type of radiation emitted depends on why the nucleus is on stable

Question 20

what are the 3 types of nuclear radiation?

Answer 20

• alpha
• beta
• gamma

Question 21

what is the most ionising radiation?

Answer 21

alpha

Question 22

what is the least ionising?

Answer 22

gamma

Question 23

alpha

Answer 23

• 2 neutrons, 2 protons
• ejected from nucleus
• likely to be absorbed
• cause damage if passing through living cells

Question 24

beta

Answer 24

• high speed electron
• ejected from nucleus as neutron which turns into a proton
• likely to cause damage if absorbed my living cells
• can penetrate the body to inner organs

Question 25

gamma

Answer 25

• electromagnetic radiation
• emitted from the nucleus
• pass through living cells without being absorbed causing ionisation

Question 26

what is radioactive contamination?

Answer 26

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

Question 27

what is irradiation?

Answer 27

irradiation:

• process of Exposing an object to nuclear radiation
• can be deliberate or accidental
• does not cause object to become radioactive

Question 28

how can you protect against unwanted irradiation?

Answer 28

• Using sources of the lowest activity possible for the shortest amount of time
• wearing appropriate protective clothing such as lead apron
• not handling sources with bare hands

Question 29

contaminated object:

Answer 29

Continues to give out radiation until decontaminated

Question 30

irradiated object:

Answer 30

does not become radioactive

Question 31

the half-life of a radioactive isotope is:

Answer 31

• The average time it takes for half of the nuclei to decay

- Time it takes for the count rate, or activity, of a sample containing isotope to fall to 50% of original value

Question 32

what happens when an alpha particle is emitted?

Answer 32

when an alpha particle is emitted:

• mass number is reduced by 4
• atomic number is reduced by 2

4
He
2

Question 33

what happens with beta decay?

Answer 33

with beta decay:

• mass number does not change
• atomic number increases by 1

0
e
-1

Question 34

what does the emission of gamma rays do?

Answer 34

The emission of gamma does not cause a change in mass or charge of the nucleus

Question 35

balanced decay equations:

Answer 35

• mass number must add up to the same number

- atomic number must have the same total