Question

A positive two ions of calcium, $C{{a}^{2+}}$ would have how many protons, electrons and neutrons?

Answer 1

Hint: In a neutral atom, numbers of electrons are always equal to the number of protons.
In a cation, number of electrons $=Z-$ Number of positive charge
In an anion, number of electrons $=Z+$ number of negative charge
Where $Z=$ Atomic number

Complete step by step answer:
In a neutral atom,
Atomic number $=$ number of electrons $=$ number of protons
Number of neutrons $=$ atomic mass $-$ number of protons/number of electrons
In an anion, number of electrons $=$ Atomic number $+$ number of negative charge present on an anion
In a cation, number of electrons $=$ Atomic number $-$ number of positive charge present on a cation
During the formation of cation the number of electrons gets decreased while the number of protons gets increased while during the formation of anion the number of electrons gets increased while the number of protons get decreased. Number of electrons increased or decreased in an ion depends upon the addition and removal of electrons. Higher the number of electrons gain higher will be negative charge on an anion and higher the number of electrons lost higher will be the positive charge on a cation.
In an anion or cation, the numbers of neutrons are calculated by the help of the following formula in which the number of protons are required only because during the formation of cation or anion number of electrons get changed.
Number of neutrons $=$ Atomic mass $-$ number of protons
Atomic number of Calcium $=20,$ atomic mass of calcium $=40$
Number of protons = atomic number $=20$
Number of neutrons $=$ Atomic mass $-$ number of protons
Number of neutrons $=40-20=20$
Here in the $C{{a}^{2+}}$ , number of electrons are calculated as follows
Number of electrons $=20-2=18$
Final answer:
In a $C{{a}^{2+}}$,
Number of electrons $=18$
Number of protons $=20$
Number of neutrons $=20$

Note:
Cations are mainly formed by metal of S-Block, D-Block and F-Block, and some metals of P-Block too, while anions are formed by non-metals of Group-IV,V,VI and VII.