Atomic Model and Radioactivity Flashcards
(43 cards)
Most alpha particles went straight through the foil
Atoms are mostly empty space
Few were deflected at large angles or straight back
The nucleus is v. dense, small and contains all the positive matter
Mass number
no. of protons plus neutrons
Atomic number
no. of protons
What is the notation of atomic no. and mass no.
The mass number is top ( A )
The atomic number is bottom ( Z )
What is mass number shortened to
A
What is atomic number shortened to
Z
Define an isotope
atoms with a different number of neutrons but the same number of protons
What is emitted in alpha decay
helium nuclei/alpha particle
What is the effect on A and Z in alpha decay
A decreases by 4, Z decreases by 2 and a new element created to balance
Describe alpha decay
2 neutrons and 2 protons are emitted from the nucleus
What is emitted in beta decay
high energy electron
describe beta decay
a neutron in the nucleus decays into a proton so a high energy electron is emitted
charge of alpha radiation
+2
Charge of beta radiation
-1
Charge of gamma radiation
no charge
Effect on A and Z in beta decay
A stays the same, Z increases by 1 and a new element to balance
What is emitted in gamma radiation
High energy EM radiation
Description of gamma radiation
Nucleus changes shape into a more stable shape, gamma radiation emitted as a result
Effect on A and Z in gamma
No change
What stops alpha
Skin or Paper
What stops beta
Thin lead or aluminium (3mm)
What reduces gamma
Thick lead or concrete
Range of alpha in air
5cm
