Atoms And Radiation Flashcards
How do electron arrangements change
When electrons change orbit moving further from the nucleus the atom absorbed electromagnetic radiation
However when electrons fall to lower orbit so closer to the nucleus the atoms emitted electromagnetic radiation
What is the mass number
The total number of protons and neutrons in an atom
How is the charge determined
On a normal neutral atom electrons=protons so cancels out
If more electrons than protons then -N
If less electrons than protons than +N
What did the foil foil experience T prove
The nucleus was positively charged
There is lots of empty space around the nucleus
The nucleus is dense
What is the information on alpha radiation
Consists of 2 protons and 2 neutrons (helium nuclei)
Stopped by few sheets of paper
Weakly penetrating (5cm)
Highly ionising
What is the information on beta radiation
Consists of electrons
Stopped by aluminium
Medium penetration (50 cm in air)
Medium ionising
What is the information on gamma radiation
Consists of electromagnetic waves
Stopped partially by lead and concrete
Highly penetrating
Lowly ionising
What is radioactive decay
Some atomic nuclei are unstable. The nucleus gives out radiation as it changes to become more stable
What is activity measured in
Becquerel (Bq)
What are alpha particles
4
Helium
2
What are beta particles
0
e
-1
What is the half life
Time taken for half of the nuclei in a sample to decay
If 80 atoms fall to 20 over 10 minutes what is the half life
80/2=40
40/2=20
So two half lives is 10 so half life is 5
What is the equation for net decline
Initial number- number after x half lives
Initial number
What is radioactive contamination
Unwanted presence of materials containing radioactive atoms on other materials
Due to decay of contaminating atoms
Transferred to an object
