Topic 6- Radioactivity

Question 1

What at the centre of a nucleus? What is their features?

Answer 1

Nucleus:
Protons-
Positively charged (+1)
Relative mass of 1
Neutrons-
Neutral (0)
Relative mass of 1

Question 2

What is found orbiting around the nucleus? What’s its features?

Answer 2

Electrons-
Found in shells
2000x smaller than protons & neutrons
Negative charge -1

Question 3

Describe how a box on the periodic table is layered out?

Answer 3

On the right ‘elemental symbol’ (element)
Bottom left ‘atomic n.o’ (how many protons & determines which element it is)
Top left ‘mass n.o’ (total n.o of protons & neutrons)
“N.o of protons & electrons are the same”

Question 4

Define isotopes

Answer 4

Atoms with the same n.o of protons but diff n.o of neutrons

Question 5

Are all elements isotopes stable? What happens to them?

Answer 5

No only one or two of an elements isotopes are stable. The other unstable isotopes decay into other elements by emitting radiation.

Question 6

Name three types of radiation

Answer 6

Alpha
Beta
Gama
Neutrons (sometimes)

Question 7

How are electrons arranged?

Answer 7

In a series of energy levels (shells) getting further away from a nucleus. Increasing in energy level.

Question 8

Can atoms jump to higher energy levels (shells)?

Answer 8

Yes they can if they gain enough energy, their ‘excited’

Question 9

Where does the energy that helps atoms to jump to different levels come from?

Answer 9

Electromagnetic radiation (if it carries just the right amount of energy to carry it to another shell)

Question 10

What happens after the electron jumps to another energy level?

Answer 10

The electron will fall back to the lower energy level and re-emit the energy as electromagnetic radiation

Question 11

What does ionising radiation mean?

Answer 11

Is able to knock electrons off atoms

Question 12

What happens when an outer electron absorbs too much energy?

Answer 12

It leaves the atom. Leaving the atom with more protons than electrons (so the atom has a positive charge). So now its a positive ion than an atom.

Question 13

What do we mean when we say a material is radioactive?

Answer 13

It consists of unstable isotopes that can decay

Question 14

What are alpha particle made up of? (in terms of particles)

Answer 14

2 proton & 2 neutrons (which is the same as the nucleus of helium so we represent them with ‘He’)

Question 15

Do alpha particles have any electrons?

Answer 15

no

Question 16

What charge do alpha particles have?

Answer 16

2+

Question 17

Describe the features of an alpha particle? (characteristics & how far it can travel)

Answer 17

• Relatively large
• Cant penetrate far into other materials
• Only travel a few cm into the air
• Absorbed by single sheet of paper
• Strongly ionising (easily knock off electrons they collide with)

Question 18

What type of atom is a beta particle?

Answer 18

an electron

Question 19

What charge do beta particles have ?

Answer 19

-1 (no mass)

Question 20

If electrons (beta particles) aren’t emitted from one the electrons shells what do they do?

Answer 20

One of the atoms neutrons decay into a proton (stays into the nucleus) and electron (emitted out at high speed)

Question 21

Describe the features of a beta particle? (characteristics & how far it can travel)

Answer 21

-Tiny
-Moderately ionising
-Penetrate moderately far into materials
(It will take several metres of air & 5 metres of aluminium to stop them)

Question 22

What are gamma rays?

Answer 22

Waves of electromagnetic radiation. Often emitted after alpha or beta radiation (nucleus way of getting rid of extra energy)

Question 23

Describe the features of a gamma ray? (characteristics & how far it can travel)

Answer 23

-No charge or mass
-Pass straight through materials
-Weakly ionising
-Penetrate really far
(travel long distances, takes thick sheets of lead or multiple metres of concrete to stop them)