Atomic number and the periodic table

Question 1

The nucleus

Answer 1

1. center of an atom.
2. Contains protons and neutrons.
3. Positive charge because of the protons.
4. Almost the whole mass of the atom is concentrated in the nucleus.

Question 2

The electrons

Answer 2

1. Move around the nucleus in electron shells.
2. Negatively charged and tiny, but they cover a lot of space.
3. Electrons has no mass.
4. Volume of the orbits determines the size of the atom