Atomic Structure P4 Flashcards
Ancient Greeks thought matter to be made of…
Invisible Particles
JJ Thomson created the…
Plum Pudding Model
Ernest Rutherford discovered that the…..by doing the…
Nucleus is small and positively charged……Alpha Particle Scattering Experiment
Niels Bohr discovered…
That electrons exist and orbit the nucleus in shells
James Chadwick determined that…
The nucleus must contain NEUTRONS as well as protons
Radius of an atom =
1 x 10 -10m
Radius of a nucleus =
1 x 10-14m
Mass number =
Protons + Neutrons
Atomic number =
Protons
Define isotope
The same element (Protons and Electrons) but with a different number of neutrons
Relative charge of a proton
+1
Relative mass of a proton
1
Relative charge of a neutron
0
Relative mass of a neutron
1
Relative charge of an electron
-1
Relative mass of an electron
0 (very small)
Gamma radiation is a
High energy electromagnetic wave that can be emitted by a nucleus but this not decay; the nucleus just has too much energy
Why is nuclear radiation dangerous?
They can ionise other atoms/molecules, which can be dangerous
Why is nuclear radiation dangerous?
They can ionise other atoms/molecules, which can be dangerous
Alpha radiation is adding a helium nuclei, so ___ is taken away from the original mass number and ___ is taken away from the original atomic number
1) 4
2) 2
During beta decay, the original mass number is unchanged but the the original atomic number has ___ added to it
1
4 Types of background radiation (radiation in the atmosphere)
-Cosmic rays from space
-Radon Gas from rocks
-Nuclear Weapons
-Medical Equipment
Mass of Alpha Radiation (Helium Nuclei)
4
Ionising power of Alpha Radiation
High
Penetrating ability of alpha radiation…. What stops it?
Low …. Stopped by paper/ a few cm of air
Use of alpha radiation
Smoke detectors
Mass of beta radiation (fast moving electron)
Basically 0
Ionising power of beta radiation
Medium
Penetrating ability of beta radiation…. What stops it?
Medium….. A few mm of Aluminium
Use of beta radiation
Thickness gauge
Mass of gamma radiation (high energy EM wave)
0
Ionising power of gamma radiation
Low
Penetrating ability of gamma radiation…What reduces intensity?
High…Reduced by concrete and lead
Uses of gamma radiation
-Radiotherapy
-Gamma knife and sterilisation
Radioactivity is the..
Rate of decay in a sample of radioactive material
Unit of radioactivity
Bq (Becquerel)
What is HALF-LIFE
The time it takes for the activity to halve
What is nuclear fission?
The splitting of a heavier nucleus (like Uranium-235) into two ‘daughter’ nuclei, releasing energy (mainly kinetic/heat) that can be used to generate electricity
Nuclear fission is INDUCED by a nucleus….
absorbing a neutron, making it more unstable
Why is nuclear fission a chain reaction?
It also releases up to 3 more neutrons which go on to induce more nuclear fission and so on
During nuclear fission and nuclear fission the total mass of particles…
Decreases because mass has been converted into energy
Nuclear fusion is the…
Joining together of two lighter nuclei (such as hydrogen, into helium) releasing kinetic energy and EM radiation
