Atomic structure Flashcards
What did Rutherford’s alpha scattering experiment prove?
- Straight through particles = empty space in the atom
- Slightly deflected = the alpha particles hit positively charged particles (protons)
- Directly backwards = positive mass was concentrated in a tiny nucleus
What was Niels Bohr’s discovery
Electrons orbit the nucleus at certain distances called energy levels
What was James Chadwick’s discoveries
Neutrons to explain the imbalance between atomic and mass numbers
Features of a proton
Mass = 1
Charge = +1
Features of a neutron
Mass = 1
Charge = 0
Features of an electron
Mass = 0
Charge = -1
Why does an atom have no overall charge
Protons always equal electrons
How can energy levels move in an atom
Absorbing or losing EM radiation
What is an isotope
An atom with the regular number of protons (same charge) but different amount of neutrons (different mass)
How many isotopes of an element are stable
1 or 2
How do unstable isotopes attempt to become stable
Decay into other elements and give out radiation to try and become stable
What is ionizing radiation
Radiation which knocks electrons off an atom, creatin an ion
Features of an alpha particle
- Helium nucleus (2 protons, 2 neutrons)
- Not very penetrating (stopped by a few cm of air and absorbed by a sheet of paper)
- Strongly ionizing
Features of a beta particle
- Fast moving electron
- Moderately penetrating (can travel a few metres of air, absorbed by a sheet of aluminium)
- For every beta particle emitted, a neutron becomes a proton
Features of a gamma ray
- Waves of electromagnetic radiation
- Very penetrating (absorbed by thick sheets of lead/ concrete)
- Weakly ionizing, as they pass straight through
Nuclear equation for an alpha particle
- 4 from the mass
- -2 from the atomic number
- a helium nucleus