Arsenic valence electrons

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Arsenic valence electrons
Arsenic valence electrons | Image: Learnool

Arsenic has 5 valence electrons.


We can write the valence electrons of arsenic using two different methods:

#1 Using periodic table
#2 Using electron configuration

Let’s break down each method in detail.

Using periodic table

Periodic table | Image: Learnool

Get the periodic table having the chemical elements marked on it as mentioned above.

Now mark the location of arsenic on the periodic table.

Arsenic location marked on periodic table | Image: Learnool

Next, mark the group number of arsenic on the periodic table.

Arsenic group number marked on periodic table | Image: Learnool

The valence electrons of each main-group element can be determined by the column in which it is located.

(i.e., all group 1 elements have 1 valence electron, all group 2 elements have 2 valence electrons, skip the transition metals… then, all group 13 elements have 3 valence electrons, all group 14 elements have 4 valence electrons, and so on up to group 18 elements)

Since arsenic is in group 15, it has 5 valence electrons.

Using electron configuration

  • First, write electron configuration of arsenic

The electron configuration of arsenic is [Ar] 4s2 3d10 4p3.

  • Second, find highest energy level in electron configuration
Green colored number represent highest energy level | Image: Learnool

In the above electron configuration, the highest energy level (4) is marked with green color.

  • Finally, count electrons of that energy level
Number circled with green color represent electrons | Image: Learnool

The 4th energy level contains 4s and 4p subshells. There are 2 electrons in the 4s subshell and 3 electrons in the 4p subshell. So arsenic has a total of 2 + 3 = 5 valence electrons.

Next: Selenium valence electrons


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