An iron atom has 26 protons in its nucleus. How many electron does it have? How many electrons does the iron ion contain?

An iron atom (symbol Fe, from the Latin ferrum) has 26 protons, 30 neutrons, and 26 electrons in its natural, neutral state.
An ion is an atom of an element that contains the same number of protons and neutrons in the nucleus, but a different number of electrons. A neutral atom has no electrical charge. The addition of electrons to the atom gives the resulting ion a negative charge, and loss of electrons gives the ion a positive charge.
Ions most often result from a chemical interaction with other elements, but they can also be created by heat or high levels of radiation.
The two most common iron ions are known as Fe(II), or Fe+2, and Fe(III), or Fe+3. The "+" means that the atom has a positive charge because it lost either 2 or 3 electrons, giving the atom a positive charge.
Therefore, Fe(II) has 24 electrons, and Fe(III) has 23 electrons.