How many electrons do these elements have in their outer shell? 1. Nitrogen 2. Chlorine 3. Calcium (b) Explain how you got your answer.
The Correct Answer and Explanation is:
Correct Answers:
- Nitrogen has 5 electrons in its outer shell.
- Chlorine has 7 electrons in its outer shell.
- Calcium has 2 electrons in its outer shell.
Explanation
To determine how many electrons are in the outer shell (also called valence electrons) of an element, we use the element’s atomic number, which tells us the total number of electrons in a neutral atom. Then we consider the electron configuration or use the element’s group number in the periodic table.
- Nitrogen (N) has an atomic number of 7, meaning it has 7 electrons. The electrons fill the shells in this order:
- The first shell holds up to 2 electrons.
- The second shell holds up to 8 electrons.
So, nitrogen’s configuration is 2 electrons in the first shell and 5 electrons in the second shell. Therefore, nitrogen has 5 outer shell electrons.
- Chlorine (Cl) has an atomic number of 17, meaning it has 17 electrons. The electron configuration is:
- 2 in the first shell
- 8 in the second shell
- 7 in the third shell
This means chlorine has 7 electrons in its outer shell. Elements in Group 17 (like chlorine) all have 7 valence electrons, which makes them very reactive as they seek to gain one more to complete their outer shell.
- Calcium (Ca) has an atomic number of 20, so it has 20 electrons. The configuration is:
- 2 in the first shell
- 8 in the second
- 8 in the third
- 2 in the fourth shell
Therefore, calcium has 2 electrons in its outer shell. Calcium is in Group 2, and elements in this group always have 2 valence electrons. These electrons are easily lost, which is why calcium readily forms positive ions.
In summary, knowing the atomic number and using either electron configuration or the periodic table group helps us determine the number of outer shell electrons.
