Atomic structure Flashcards
(20 cards)
What is the typical radius of an atom?
1 x10^-10 metres
The radius of the nucleus is ____ times smaller than the radius of the atoms.
10,000
Describe how an electron can move between energy levels.
an electron can move into a higher energy kevel by absorbing EM radiation, and move into a lower energy level by emitting EM radiation
Which subatomic particle determines which element the atom is?
the number of protons
Which particles r stable?
Only one/two of an elements isotopes are stable
How do elements decay into other elemtns?
they emit alpha, beta, gamma radiation or emit a nuutron
How does an electron leave an atom?
it absorbs so much eleectromagnetic radiiation that it is able to completely leave an atom
What does ionising radiation mean?
- ablle to knock electrons off
What are the 4 types of nuclear radiation?
beta
aplha
gamma
neutrons
What are alpha particles made of?
2 protons, 2 neutrons (NO NEUTRONS)
What are the alpha particles’ charge?
2+
Why are alpha particles not very penetrating?
-they are relatively large, they are easily stopped by collisions with other molecules.
-so they can travel a few centimetres in the air and can be absorbed by a mall peice of paper
What makes alpha particles strongly ionising?
- large size and strong charge means thaey can easily knockelectrons of any atoms they collide with
How do beta particles come about?
- one of an atoms neutrons decays into a proton and electron.
-proton stays in nucleus
-electron is emitted out at high speed
Why are they moderately ionising and moderately penetrating?
- they are very small
-takes several metres of air or 5mm of aluminium to stop them
When is gamma radiation emitted?
- often emitted after alphha or beta radiation
Why do gamma rays pass straight through materials?
they dont have any mass nor charge
Why are gamma rays weakly ionising?
They pass straight through the materials rather than colldiing with any atoms
(also no charge nor mass)
Describe gamma radiations penetrating ability.
- can travel long distances
-thick sheets of lead or multiple metres of concrete to stop thewm
When are neutrons emitted?
When there are too many neutrons in an unstable isotopse, the nucleus emits it (throws it out) to make the atom more stable
