Answer:
3. Group
5. Valence electron
6. The atomic number tells you the presence of proton and electron.
Explanation:
The electrons which are present in the last shell or orbit is called valence electron and the shell is valance shell. When you go from left to the right side of the periodic table, number of shells remains the same but number of electron increases while when we go from top to bottom of periodic table, number of shell increases but the number of valance electrons remains the same.
