P4 - ATOMIC STRUCTURE / NUCLEAR PHYSICS Flashcards
What did JJ THOMPSON CREATE?
The PLUM PUDDING MODEL.
What did ERNEST RUTHERFORD discover?
Nucleus was small and positively charged, electrons orbit far away.
What did NEILS BOHR discover?
Electrons exist in shells.
What did JAMES CHADWICK discover?
Protons and neutrons exist in the nucleus.
What is an ISOTOPE?
Same element, but different numbers of neutrons.
What happens to UNSTABLE NUCLEI?
They will DECAY to become more stable, emitting radiation in the process.
What can RADIATION do to atoms/molecules?
IONISE THEM, which can be dangerous.
What is GAMMA RADIATION?
High energy EM wave that can be emitted by a nucleus, not due to decay; due to nucleus having excess energy.
What is ALPHA DECAY?
Larger nuclei; nucleus ejects a HELIUM NUCLEUS (2 protons + 2 neutrons).
This is called ALPHA RADIATION.
What is BETA DECAY?
Smaller nuclei; a NEUTRON decays into a proton and an electron.
High energy ELECTRON is BETA RADIATION.
What is an example of a DEACY EQUATION for ALPHA DECAY?
241 Am –> 237 Np + 4 He
95 93 2
What is an example of a DECAY EQUATION for BETA DECAY?
14 C –> 14 N + 0 e-
6 7 -1
PROPERTIES OF ALPHA RADIATION
- HIGH ionising power
- LOW penetrating ability (can be stopped by paper/few cm of air)
-Used in smoke detectors
PROPERTIES OF BETA RADIATION
-MEDIUM ionising power
-MEDIUM penetrating ability (can be stopped by aluminium)
-Used as a thickness gauge.
PROPERTIES OF GAMMA RADIATION
-LOW ionising power
-HIGH penetrating ability (cant be stopped but intensity can be reduced by lead + concrete )
-Used for radiotherapy and sterilisation.
