atomic structure physics p1

Question 1

what it is the radius of an atom

Answer 1

1x10 to power of -10m

Question 2

what is the radius of the nucleus of an atom

Answer 2

1/10000

Question 3

what does the nucleus contain

Answer 3

nucleus contain s the mass and the positive charge(protons and neutrons)

Question 4

what are elctrons arrangment

Answer 4

electrons, energy level the higher the energy the further from the nucleus ( gain and lose EM radiation)

Question 5

what is the atomic number

Answer 5

the number of protons and neutrons in an atom is called its mass number

Question 6

what is the mass number

Answer 6

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

Question 7

what are isotopes

Answer 7

have the same number of protons different number of neutrons ( do not talk about electrons)

Question 8

what are ions

Answer 8

ions are charged particles

Question 9

what happen to the charge if you gain an electron

Answer 9

negative charge

Question 10

what happen when you lose an electron

Answer 10

positive charge

Question 11

compare the stucture of an atom of carbon-14 with the structure of an atom of carbon-12( 3 MARKS)

Answer 11

similarities
same number of protons
or same atomic number
same number of electrons
differences-
different number of neutrons
or
different mass number

Question 12

explain how an electron can move up and down between energy levels in an atom(2mark)

Answer 12

to move to a higher energy level an electron absorbs energy from electromagnetic radiation

to move to a lower energy level an electrons emits energy in the form of electromagnetic radiation

Question 13

developmet of the model of the atom

Answer 13

before discovery of electron, atoms were thought to be tiny spheres that could not be divided

the discovery of the electron lead to the plumpudding model of the atom.,the plum pudding model suggetsted that the atom is a ball of positive charge with the negative electrons embedded in it

the results form the alpha particle scatterinbg experiment lead to the conclusion that the mass of an atom was concentrated at the center( nucleus)
andf that the nucleus is charged.this nuclear mode

Answer 14

the results form the alpha particle scatterinbg experiment lead to the conclusion that the mass of an atom was concentrated at the center( nucleus)
andf that the nucleus is charged.this nuclear modelreplaced the plum pudding model

Answer 15

bhor adapted the nuclear model by suggesting that the electrons orbit the nucleus at specific distances. the theorical calculation of bhor agreed with experimental observations .
later experiments lead to to the idea that the positive charge of any nucleus could be subdivided into whole number of smaller particles, each particles having the same amount of positive charge.the name protons was given to this particles

Question 16

whay did chadwick did

Answer 16

this experimantal work of chadwichk provided the evidence to show the exsictence of neutrons within the nucleus. this was about 20 years after the nucleus becamer an accepted scientif idea, by observing the alpha scattering experiment analyse.

Question 17

explain why alpha particles bounce back ( 2 mark)

Answer 17

both alpha particles and the grid nucleus have positive/same charge

so alpha particle and the gold nucleus repel each other

Question 18

explain why the paths of alpha particles B( at the top of c) is more tightly curved( steepest) more than C that is not as steep but still curve

Answer 18

particle b passes close to the nucleus
so experiences a stronger repulsive force or
experinces a stronger electric field

Question 19

what happen to an unstabel nuclei

Answer 19

the nucleus gives out radiation as as it changes to become more stable. this is a random process called radioactive decay.

Question 20

what is the activity

Answer 20

rate at which a source of unstable nucleis decays

Question 20

what is the activity measured in

Answer 20

becquerel(Bq)

Question 21

what is count-rate

Answer 21

is the number of decays recorded each second by a dectector

Question 22

what is the name of the detector that is used to maesure the count rate.

Answer 22

geiger muller tube

Question 23

what is an alpha particle

Answer 23

this consist of two neutrons and two protons , this is the same as the a helium nucleus

Question 24

what is a beta particle

Answer 24

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

Question 25

what is gamme rays

Answer 25

electromagnetic radiation from the nucleus.

Question 26

how far away can alpha travel, and ionising power

Answer 26

few cm, stopped by skin, very high ionising power

Question 27

how far do beta travel, and ionising power

Answer 27

few meters in air, stopped by a 5 mm aluminium, moderate ionising power

Question 28

how far do gamma travel, ionising poer

Answer 28

few km and can penetrate the skin, thin metals but can be stopped by thick lead or concrete,low ionising power compared o beta and alpha.

Question 29

explain why the worker needs to stand close to the radiation detector( 2 mark)

Answer 29

some radioactive materials emit alpha radiation which has a very short range in air- need to have both points to get a mark.

Question 30

what happen to an alpha particle if is dacaying

Answer 30

alpha mass atomic decrases by 2 and mass decreases by 4, helium at the end

Question 31

what happen when an beta particle if is decaying

Answer 31

beta atomic increases by 1 and the mass stays the same. electron at the end

Question 32

what is half-life

Answer 32

of a radioactive isotope is the time it takes for the number for the number of nuclei of the isotope in a sample to halve, or the number of nucli of the isotope in a sample to halve, or the time it takes for the countrate( or activity) from a sample containing the isotope to fall to half of its initial level.

Question 33

how many are 2 half-lives

Answer 33

1/4 nuclei reamain

Question 34

hoe many 3 half lives

Answer 34

1/8 of the nuclei remain.

Question 35

what is radioactive contamination

Answer 35

is the unwanted presence of materials containing radioactive atoms on other materials, the hazard from the contamination is due to the decay of the contaminating atoms. the type of radiation affect the level of hazard.

Question 36

what is irradiation

Answer 36

is the process of exposing an object to nuclear radiation, but the irradiated object dose not become radioactive.

Question 37

what are precoutions of radioactive contamination

Answer 37

distance- tongs arms lenght protective clothing - gloves barriers- lead shielding

Question 38

what is background radiation

Answer 38

its around us all the time. it comes from- natural source s such as rocks and cosmic rays from the space. or man made sources such as fall out from nuclear weapons testing and nuclear accidents

Question 39

how is radiation dose measured in

Answer 39

sieverts , 1000millisieverts=1 sievert

Question 40

what are hazards linked to half life

Answer 40

Short half life means a high rate of decay so high exposure quickly But it does mean that it will leave the body quickly – medical tracers Long half life means limited exposure over time but it will last for longer so you get prolonged exposure – nuclear power

Question 41

where can nuclear radiation used

Answer 41

exploration of internal organs control or desctruction of unwanted tissue

Question 42

what is nuclear fission

Answer 42

splitting of a large and unstable nucleus, into 2 smaller nuclei and emits 2 or three neutron plus gamma rays . energy is relased , all fission products have kinetic energy

Question 43

what is explosion of nuceal weapons caused by

Answer 43

uncontrolled chain reactions, caused by neitrons

Question 44

what is nuclear fusion

Answer 44

is the joining of two light nuclei to form a heavier nucleus. in this process some of the mass may be converted into the energy of radiation.