First, we write the atom with 24 electrons. Atoms are neutral, so their electrons and protons are equal in number. The element with proton number 24 is chromium.
Next, a manganese atom has 25 electrons, so if it forms a cation with a +1 charge, it will have 24 electrons. Similarly, if an iron atom which normally has 26 electrons forms a +2 charge cation, it also has 24 electrons. The three symbols are:
Cr
Mn⁺¹
Fe⁺²
