How many core and valence electrons does one atom of magnesium (Mg) have? 2 core and 10 valence 6 core and 6 valence 10 core and 2 valence 4 core and 8 valence
The Correct Answer and Explanation is:
Correct Answer: 10 core and 2 valence
Magnesium (Mg) has an atomic number of 12, indicating it possesses 12 electrons in a neutral atom. These electrons are distributed among various energy levels or shells based on the principles of atomic structure.
The electron configuration of magnesium is:
1s² 2s² 2p⁶ 3s²
This notation shows that:
- The first energy level (1s²) contains 2 electrons.
- The second energy level (2s² 2p⁶) contains 8 electrons.
- The third energy level (3s²) contains 2 electrons.
Electrons located in the innermost shells (1s and 2s/2p) are referred to as core electrons. These do not participate in bonding or chemical reactions under normal conditions. In this case, the 2 electrons in the 1s orbital and the 8 electrons in the 2s and 2p orbitals make up the 10 core electrons in magnesium.
Electrons in the outermost shell, which in this case is the 3s², are called valence electrons. These are the electrons involved in chemical bonding and determine the chemical properties of the element. For magnesium, there are 2 valence electrons in the 3s orbital.
Valence electrons play a critical role in the formation of chemical compounds. Magnesium, with its 2 valence electrons, often loses both during chemical reactions to achieve a stable noble gas configuration, forming a Mg²⁺ ion in the process.
In summary, a neutral magnesium atom contains 10 core electrons and 2 valence electrons, corresponding to the electron distribution up to the third energy level.
