Write the chemical symbol for three different atoms or atomic cations with 24 electrons

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