Question

An atom has the following electron configuration.

1s22s22p63s23p3

How many valence electrons does this atom have?

3
5
8
15

Answers

GPT-4o mini
To determine the number of valence electrons in the given electron configuration (1s² 2s² 2p⁶ 3s² 3p³), we need to consider the electrons in the outermost shell, which is the highest principal energy level (n).

In this case, the outermost shell is the third shell (n=3) and contains the following electrons:

- 3s² (2 electrons)
- 3p³ (3 electrons)

Now, we can sum these electrons:

- 2 (from 3s) + 3 (from 3p) = 5 valence electrons.

Therefore, the atom has **5 valence electrons**. The correct answer is **5**.

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