6. Radioactivity Flashcards
Describe the structure of an atom
A positively charged nucleus, surrounded by negatively charged electrons
What makes up most of the mass of an atom?
The nucleus—protons and neutrons
Approximately how big are atoms
0.1 nm
Approximately how big or small molecules?
0.2 nm
Which number tells you the number of protons?
Atomic number
Which number tells you the number of nucleons?
Mass number
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
Charge of a proton
+1
Charge of a neutron
0
Charge of an electron
-1
Why are atoms neutral?
The number of positive protons equals the same number of negative electrons
What happens when atoms absorb or an emit electromagnetic radiation?
Electrons change orbit
How can atoms form positive ions?
By loosing radiation
Give origin of three background radiation
Cosmic rays, rocks and soil, living things
