Question

How do you determine an atom or ions expected size? I've tried following the rules for atomic radius, but it is not working. please help!

Answer 1

RULES

1)The size of an atom or ion depends on the size of the nucleus and the number of electrons.

2)Generally atoms with higher numbers of electrons have larger radii than those with smaller numbers of electrons

3)The number of positive charges in the nucleus determines both the number of electrons that surround an atom and the number of electrons that can be lost or gained to form ions.

• Thus as the charge on the ion becomes more positive, there will be less electrons and the ion will have a smaller radius.
  
• As the charge on the ion becomes more negative, there will be more electrons and the ion will have a larger radius.
  
• As the atomic number increases in any given column of the Periodic Table, the number of protons and electrons increases and thus the size of the atom or ion increases.