Answer :
- Identify the outermost electron shell: In Magnesium, it's the n=3 shell.
- Determine valence electrons: Magnesium has 2 valence electrons in the $3s^2$ subshell.
- Determine core electrons: Magnesium has 10 core electrons in the $1s^2 2s^2 2p^6$ subshells.
- Final Answer: Magnesium has 10 core electrons and 2 valence electrons.
### Explanation
1. Understanding the Problem
We are given the electron configuration of Magnesium (Mg) as $1s^2 2s^2 2p^6 3s^2$. We need to determine which electrons are core electrons and which are valence electrons. Core electrons are those in the inner, filled shells, while valence electrons are those in the outermost shell.
2. Identifying Electron Shells
The electron configuration is $1s^2 2s^2 2p^6 3s^2$. The principal quantum numbers (n) represent the electron shells. Here, we have electrons in shells n=1, n=2, and n=3.
3. Determining Valence Electrons
The outermost shell is the one with the highest principal quantum number, which is n=3 in this case. The electrons in the 3s subshell are the valence electrons. From the electron configuration, we see that there are 2 electrons in the 3s subshell ($3s^2$). Therefore, Magnesium has 2 valence electrons.
4. Determining Core Electrons
All electrons that are not valence electrons are core electrons. In this case, the core electrons are those in the n=1 and n=2 shells. The electron configuration for these shells is $1s^2 2s^2 2p^6$. This means there are 2 electrons in the 1s subshell, 2 electrons in the 2s subshell, and 6 electrons in the 2p subshell. In total, there are $2 + 2 + 6 = 10$ core electrons.
5. Final Answer
Therefore, Magnesium (Mg) has 10 core electrons and 2 valence electrons.
### Examples
Understanding core and valence electrons is crucial in chemistry for predicting how elements will interact to form chemical bonds. For example, magnesium, with its two valence electrons, readily forms ionic bonds with elements like oxygen or chlorine to achieve a stable electron configuration, leading to the formation of compounds like magnesium oxide (MgO) or magnesium chloride (MgCl2). This concept is fundamental in designing new materials and understanding chemical reactions.
- Determine valence electrons: Magnesium has 2 valence electrons in the $3s^2$ subshell.
- Determine core electrons: Magnesium has 10 core electrons in the $1s^2 2s^2 2p^6$ subshells.
- Final Answer: Magnesium has 10 core electrons and 2 valence electrons.
### Explanation
1. Understanding the Problem
We are given the electron configuration of Magnesium (Mg) as $1s^2 2s^2 2p^6 3s^2$. We need to determine which electrons are core electrons and which are valence electrons. Core electrons are those in the inner, filled shells, while valence electrons are those in the outermost shell.
2. Identifying Electron Shells
The electron configuration is $1s^2 2s^2 2p^6 3s^2$. The principal quantum numbers (n) represent the electron shells. Here, we have electrons in shells n=1, n=2, and n=3.
3. Determining Valence Electrons
The outermost shell is the one with the highest principal quantum number, which is n=3 in this case. The electrons in the 3s subshell are the valence electrons. From the electron configuration, we see that there are 2 electrons in the 3s subshell ($3s^2$). Therefore, Magnesium has 2 valence electrons.
4. Determining Core Electrons
All electrons that are not valence electrons are core electrons. In this case, the core electrons are those in the n=1 and n=2 shells. The electron configuration for these shells is $1s^2 2s^2 2p^6$. This means there are 2 electrons in the 1s subshell, 2 electrons in the 2s subshell, and 6 electrons in the 2p subshell. In total, there are $2 + 2 + 6 = 10$ core electrons.
5. Final Answer
Therefore, Magnesium (Mg) has 10 core electrons and 2 valence electrons.
### Examples
Understanding core and valence electrons is crucial in chemistry for predicting how elements will interact to form chemical bonds. For example, magnesium, with its two valence electrons, readily forms ionic bonds with elements like oxygen or chlorine to achieve a stable electron configuration, leading to the formation of compounds like magnesium oxide (MgO) or magnesium chloride (MgCl2). This concept is fundamental in designing new materials and understanding chemical reactions.
