What are isotopes?
Elements with the same number of protons but different number of neutrons
What did Niel Bohr discover about electrons?
They orbit the nucleus in shells.
Why did Mendeleev leave gaps in his periodic table?
He predicted that there were elements that existed that had not yet been discovered. He also predicted their mass and properties.
What happened in the alpha-scattering experiment?
Alpha particles were shot at a piece of gold foil. Most of the alpha particles went through the gold foil, some deflected and some bounced back.
What is the overall charge of an atom?
0
Where is the mass of an atom concentrated?
In the nucleus