What does the nucleus of an atom contain?
- Protons
- Neutrons
What does the atomic number represent and what does the mass number represent?
- Atomic number: how many protons it has
- Mass number: protons + neutrons
What are the relative mass and charges of protons, neutrons, and electrons?
- Protons: 1, +1
- Electrons: 0, -1
- Neutrons: 1, 0
Why are atoms neutral?
They have the same number of protons and electrons, balances charge out.
How many electrons have the outer shells hold?
2 in the first shell, 8 in every other shell.
What is an isotope?
Elements with the same atomic number but different mass numbers, has a different number of neutrons.
What does the position of an atom in the periodic table mean?
- Group number (columns) represents how many electrons are in the outer shell
- Period number (rows) represents how many shells it has
Who developed the theory of atoms?
John Dalton
Who found evidence to support John Dalton’s theory and made the first model of an atom?
- J.J Thomson
- Rutherford
- Bohr
Who contributed to the model of the atom later?
- Geiger
- Marsden
