Atomic Number and Electron Configuration

The atomic number of an element represents the number of protons in the nucleus of an atom. It also determines the number of electrons in a neutral atom. To find the electron configuration of an element, we can use the Aufbau principle, which states that electrons occupy the lowest energy orbitals first.

Electron Configuration of Element with Atomic Number 26

The atomic number 26 corresponds to the element iron (Fe). To determine the electron configuration of iron, we can use the periodic table as a guide.

1. Identify the Period and Group of the Element

Iron is located in period 4 and group 8 (or group 8B). In the periodic table, the periods correspond to the energy levels or shells, while the groups represent the number of valence electrons.

2. Determine the Number of Electrons in Each Energy Level

In the ground state, all the electrons of an atom are arranged in the lowest energy levels possible. Each energy level has a maximum number of electrons it can hold, based on the formula 2n², where n is the principal quantum number.

For iron (Fe), the electron configuration can be represented as:

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

3. Count the Electrons in the M-Shell

The M-shell refers to the third energy level (n = 3), which includes the 3s, 3p, and 3d orbitals. From the electron configuration, we can see that iron has a total of 2 electrons in the 3s orbital, 6 electrons in the 3p orbital, and 6 electrons in the 3d orbital.

Therefore, the M-shell of iron in the ground state contains a total of 2 + 6 + 6 = 14 electrons.

Summary

In summary, the element with atomic number 26, which is iron (Fe), has an electron configuration of 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶. The M-shell, corresponding to the third energy level (n = 3), contains a total of 14 electrons.