Magnesium contains 12 protons, 12 neutrons and 12 electrons. The 12 electrons are distributed across shells in the electronic configuration 2, 8, 2, placing two in K-shell, eight in L-shell and two in M-shell.
Magnesium is essential for many biological processes, including muscle contraction. For an atom of magnesium with a mass number of 24 and atomic number 12, determine the number of (i) protons, (ii) neutrons, (iii) electrons and also illustrate the arrangement of electrons in a magnesium atom.
Share
For magnesium, the atomic number of 12 establishes 12 protons and 12 electrons in a neutral atom. Subtracting the atomic number from the mass number 24 yields 12 neutrons. Applying the Bohr-Bury rules, the arrangement of its twelve electrons across energy shells is K-shell contains 2 electrons, L-shell contains 8 electrons and M-shell contains 2 electrons, written as 2, 8, 2.
For more NCERT Solutions of Class 9 Science Exploration Chapter 8 Journey Inside the Atom Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-8/