Why is the second ionization energy of potassium greater than the second ionization energy of calcium?

Answer 1

The atomic number of potassium is 19. The outer shell of potassium contains one electron. It can attain a stable configuration by loosing this electron. This is the reason that potassium forms k+ ions.

Similarly, calcium contains two electrons in its outer shell and attain stable configuration by loosing the 2 electrons. Thus, it forms Ca2+ ions.

Answer 2

Well, that's because K atom is the neutral atomic form, having 19 protons in the core and 19 electrons, but the K+ ion has 19 protons (19 positive charge) and only 18 electron (18 negative charge). This means, the effective attraction of the electrons is bigger, because not one proton has to attract one electron, but 19/18 proton has to attract one electron. More effective attraction pulls the remaining 18 electron closer to the positive core, making the potassium and all the other alkalimetal (Li, Na, K, Rb, Cs, Fr) ions' electron cloud smaller. And also that's the reason for the halogenic negative ions (F,Cl,Br,I) to be bigger than the atom: they have more negative charge, so the eletrcons are not as attracted to the core as they are in the atomic form.

Answer 3

Potassium the Molar Mass is 39, the molar mass of calcium is 40

Potassium has 19 protons and 20 neutrons, because the atomic number of potassium is 19

Calcium has 20 protons and 20 neutrons, because the atomic number of calcium is 20

The mass from potassium is smaller then the mass of calcium, because there are less protons. That also explains why the size is different. If there is less, then the molecule is smaller.

Answer 4

There is only one electron in outermost shell of Potassium atom so the removal of 2nd electron from inner octet requires very high amount of heat so 2nd ionization energy for Potassium is very high, in case of Calcium there are two electrons in outermost shell so the removal of 2nd electron from the same shell does not requires a very high amount of heat.

Answer 5

A neutral potassium atom has one electron in its outer shell. Therefore, to form a potassium ion, this outer electron is lost. As electrons have a negative charge and one of these electrons is lost, the atom now has more protons (positively charged subatomic particles in the nucleus) than electrons, so the net charge on the ion is positive. It has a charge of 1+ as it has lost one electron. If it had lost 2 electrons, it would have a charge of 2+ and so on. If it had gained an electron, it would have a charge of 1-.