Write the condensed electron configurations for the following atoms and indicate how many unpaired electrons each has: (a) Mg.

Verified step by step guidance

1. Identify the atomic number of Magnesium (Mg) from the periodic table, which is 12. This tells us that a neutral magnesium atom has 12 electrons.
2. Write the full electron configuration for Mg. Since Mg is in the third period and the s-block of the periodic table, its electrons will fill the 1s, 2s, 2p, and 3s orbitals.
3. Condense the electron configuration by using the nearest noble gas preceding Mg in the periodic table, which is Neon (Ne), and then add the remaining electron configuration beyond Ne.
4. The condensed electron configuration for Mg will be represented as [Ne] followed by the configuration of the electrons that are in higher energy levels than those in Ne.
5. Determine the number of unpaired electrons by examining the electron configuration in the outermost shell. Since the 3s orbital is fully filled with two electrons, both paired, Mg has zero unpaired electrons.

Key Concepts

Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. It is represented using a notation that indicates the energy levels and sublevels occupied by electrons. For example, magnesium (Mg) has an atomic number of 12, leading to the electron configuration of 1s² 2s² 2p⁶ 3s², which shows how electrons fill the available orbitals.

Unpaired Electrons

Unpaired electrons are those that occupy an orbital alone, without a partner of opposite spin. The presence of unpaired electrons is crucial for understanding an atom's magnetic properties and reactivity. In the case of magnesium, its electron configuration reveals that there are two unpaired electrons in the 3s orbital, which influences its chemical behavior.

Hund's Rule

Hund's Rule states that electrons will fill degenerate orbitals (orbitals of the same energy) singly before pairing up. This principle helps minimize electron-electron repulsion and stabilizes the atom. Understanding this rule is essential for determining the number of unpaired electrons, as it explains why the 3s orbital in magnesium has two unpaired electrons instead of one paired electron.