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So I'm still struggling with cations and anions.. so when its Na+ its a cation but can someone explain to me the difference in size? I remember something about the more protons, the smaller and the less protons, the bigger.. why is that???
As you move from left to right on a periodic table, the number of protons is increasing but the number of shells stays the same (n). Thus, the increase in protons increases the effective nuclear charge on the electrons and pulls them in tighter, so both atomic and ionic radius decrease as you move from left to right. As you move from up to down on the periodic table, the number of shells increases (n increases), so the atomic radius will increase. In the example for Na, Na+ has a smaller radius than Na, because Na+ has lost an electron and so the effective nuclear charge increases, so the radius will decrease.
Cations are ions that have lost an electron/electrons. Since they have less electrons, the nucleus is able to pull them in more tightly. On the other hand, anions gain electrons. Having more electrons will cause more repulsion, leading to a larger size, relative to its parent atom.
cations tend to be smaller in size because the positive charge of the atom is stronger than the negative charge of the atom. There is also less electron shielding, so the outer electrons are pulled in tighter by the positive nucleus.
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