ATOMIC STRUCTURE

Question 1

What did john dalton say about atoms

Answer 1

solid spheres

Question 2

who did plum pudding model

Answer 2

jj thompson

Question 3

what did the plum pudding model (jj thompson) propose

Answer 3

atom = general ball of positive charge w/ negative electrons embedded in it

Question 4

what did ernest rutherford do

Answer 4

gold foil experiment

Question 5

what did the gold foil experiment prove

Answer 5

nucleus as ball of positive charge (repelled the negative alpha particles)
most of mass concentrated in nucleus
most of atom = empty space

Question 6

what did neils bohr propose

Answer 6

electrons orbit the nucleus and are in energy shells

Question 7

what did james chadwick invent

Answer 7

NEUTRONS - neutral particles

Question 8

When Democritus first conceived of atomic theory, around 500 BC, how did he describe atoms?

Answer 8

spsarated by tiny space
small spheres
smallest possible unit of matter

Question 9

One issue with Rutherford’s nuclear model was that the atom should collapse as the negative electrons would be attracted to the positive nucleus, causing them to rush inwards.
In response to this, in 1913 Bohr suggested that electrons ___________________, which kept the atom from collapsing.

Answer 9

orbit the nucleus in shells

Question 10

what is mass no

Answer 10

no of protons + no of neurtons

Question 11

def isotope

Answer 11

atoms w same no protons, but diff no of neutrons

Question 12

ionisation def

Answer 12

when electrons absorb enough energy to leave an atom

Question 13

radioactive def

Answer 13

consistes of unstable isotopes that can decay

Question 14

alpha particel nucelus

Answer 14

same as helium nucleus
2 protons
2 neutrons

Question 15

alpha particle charge

Answer 15

2+ - dont have any electrons

Question 16

alpha penetrating ability

Answer 16

low - absorbed by few cm of air / paper

Question 17

alpha ionising power

Answer 17

v strong - easily knock electrons of any atoms they collide with

Question 18

charge of beta particles

Answer 18

-1

Question 19

beta decay process

Answer 19

one of neutrons in nucleus is shot out and decays into proton and electron
proton stays in nucleus but electron emitted out at high speed

Question 20

beta ionising and penetrating power

Answer 20

moderate

Question 21

what is beta absorbed by

Answer 21

several m of air / 5mm of al to stop

Question 22

do gamma rays have mass/charge

Answer 22

NO - waves of EM radiation

Question 23

gamma ionising and penetrating power

Answer 23

weakly ionising
highly penetrating - travel long distances in air

Question 24

what is gamma rays absorbed by

Answer 24

thick sheets of lead
many m of concrete

Question 25

why does emmision of neutron occur

Answer 25

if nucleus has too many neutrons so unstable it may shoot one out to become more stable

Question 26

A beta particle is the same as an electron. What is the source of the beta particle?

Answer 26

A neutron decaying into a proton and an electron

Question 27

What you minus for an alpha partice decay question

Answer 27

subtract 4 from the atomic mass (top number), and 2 from the atomic number (bottom number).

Question 28

what hapens in beta decay equations

Answer 28

the atomic mass (top number) stays the same, and the atomic number (bottom number) increase by one +1 electron

Question 29

what happens in gama decay equations

Answer 29

NO CHANGE

Question 30

what happens in neutron emission equations

Answer 30

looses 1 neutron - minus 1 from mass no. 9 8 Be ----------> Be + 1 neutron 4 4

Question 31

activity def

Answer 31

overall rate of decay of all the isoptoped in a sample measured in Bq

Question 32

half life def (2 possible)

Answer 32

the time taken for the no. of radioactive nuclei in a sample to halve the time taken for the no. of decays or activity to half

Question 33

What does a geiger muller tube and counter do

Answer 33

record all the decays that reach them each second

Question 34

irradiation def

Answer 34

The process by which objects are exposed to radiation of any type

Question 35

contamination def

Answer 35

when radioactive particles get onto other objects

Question 36

what deterines how harmful radiation is

Answer 36

how ionising it is ionising = can enter living cells and interact w the molecules inside ionise our DNA , cause mutations

Question 37

what does the amount of radiation you get depend on

Answer 37

how far away from the source you are how long you're exposed how radioactive that substance is

Question 38

precautions to minimise radiation

Answer 38

gloves overalls keep in lead lined box tongs

Question 39

Which radioactive substance is the most harmful inside the body and why?

Answer 39

alpha because its the most ionising

Question 40

True or false? Once you've become irradiated, you become radioactive and can emit radiation to others.

Answer 40

false