Answer – A neutral atom of iron has 26 protons, 30 neutrons, and 26 electrons. These numbers vary when iron is in any of its ionic or isotopic forms.

Explanation:

Iron, which belongs to Group 8 of the periodic table, is a transition metal. Due to the varying number of valence electrons in its d-orbital, the element is unstable with its properties transitioning between the s-block elements on the left and the p-block elements on the right.

But like with any other element, the number of its protons, neutrons, and electrons can be found using its atomic and mass numbers from the periodic table. 

Fe in its neutral atomic state

To calculate the number of protons and electrons in a neutral iron atom, its atomic number must first be identified from the periodic table.

⇒ Atomic number of Fe = 26

This atomic number is equal to the number of protons in an iron atom.

So the number of protons in one atom of Fe is 26.

Further, the number of protons is the same as the number of electrons in a neutral iron atom.

Thus, an iron atom has 26 electrons.

Now, to find the number of neutrons, the mass number of Fe ought to be found from the periodic table.

⇒ Mass number of Fe ≈ 56

Since the mass number is the sum of the protons and neutrons in one atom of an element:

Number of protons in Fe = Mass number of Fe – Proton number of Fe = 56 – 26 = 30

So a neutral iron atom has 30 neutrons.

A neutral iron atom has 26 protons, 26 electrons, and 30 neutrons.

Fe in its isotopic forms

When the species of iron being considered is an isotope, the number of electrons and protons in it will be the same as that in the neutral atom but the number of neutrons will vary.

Iron has 2 other isotopes besides ⁵⁶Fe; they are ⁵⁷Fe and ⁵⁴Fe. To find the number of neutrons in each of these, the proton number must be subtracted from the respective mass numbers.

So ⁵⁷Fe will have 57 – 26 = 31 neutrons, while ⁵⁴Fe will have 54 – 26 = 28  neutrons. Both species will, however, contain 26 protons and 26 electrons each.

Fe in its ionic forms

Iron exists in its ionic form as either Fe²⁺ or Fe³⁺. These consist of a varying number of electrons but the same number of protons and neutrons.

Fe²⁺ is formed from the loss of 2 valence electrons. Therefore, it has 26 – 2 = 24 electrons with 26 protons and 30 neutrons.

Fe³⁺, on the other hand, is the ion resulting from the loss of 3 valence electrons. So it has 26 – 3 = 23 electrons.

Popular Questions