How Many Valence Electrons Does Arsenic (As) Have?

Arsenic is the 33rd element in the periodic table and the 3rd element in group 15. Arsenic is a notoriously toxic heavy metal and its symbol is ‘As’. The valence electrons are the total number of electrons in the last orbit(shell).

The total number of electrons in the last shell after the electron configuration of arsenic is called the valence electrons of arsenic. The last shell of arsenic has five electrons. Therefore, the valence electrons of arsenic are five.

The valence electrons determine the element’s properties and participate in forming bonds. Arsenic participates in the formation of bonds through its valence electrons.

This article discusses how to calculate the number of valence electrons in arsenic easily. Hopefully, after reading this article you will know in detail about this.

How do you calculate the number of valence electrons in an arsenic atom?

The valence electrons have to be determined by following a few steps. The electron configuration is one of them. It is not possible to determine the valence electron without electron configuration.

Knowing the electron configuration in the right way, it is very easy to determine the valence electrons of all the elements.

However, valence electrons can be easily identified by arranging electrons according to the Bohr principle. Now we will learn how to determine the valence electron of arsenic.

Step-1: Determining the total number of electrons in arsenic

1st we need to know the total number of electrons in the arsenic atom. To know the number of electrons, you need to know the number of protons in arsenic. To know the number of protons, you need to know the atomic number of the arsenic element.

To know the atomic number we need to take the help of a periodic table. It is necessary to know the atomic number of arsenic elements from the periodic table. The atomic number is the number of protons. Electrons equal to protons are located outside the nucleus.

That is, we can finally say that there are electrons equal to the atomic number in the arsenic atom. From the periodic table, we see that the atomic number of arsenic is 33. That is, the arsenic atom has a total of thirty-three electrons.

Step-2: Need to do electron configuration of arsenic

Step 2 is very important. In this step, the electrons of arsenic have to be arranged. We know that arsenic atoms have a total of thirty-three electrons. The electron configuration shows that the first shell of arsenic has two electrons, the second shell has eight electrons, the 3rd shell has eighteen electrons and the 4th shell has five electrons. Therefore, the number of electrons per shell of arsenic is 2, 8, 18, 5.

Step 3: Determine the valence shell and calculate the total electrons

The third step is to diagnose the valence shell. The last shell after the electron configuration is called the valence shell. The total number of electrons in a valence shell is called valence electrons.

The electron configuration shows that the last shell of arsenic has five electrons. Therefore, the valence electrons of arsenic are five.

How many valence electrons does an arsenic ion(As^3-) have?

The elements that have 5, 6, or 7 electrons in the last shell receive the electrons in the last shell during bond formation. The elements that receive electrons and form bonds are called anions.

During the formation of a bond, the last shell of arsenic receives three electrons and turns into an arsenic ion(As^3-). That is, arsenic is an anion element.

As + 3e^– → As^3-

The electron configuration of arsenic ion(As^3-) is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶. This electron configuration shows that the arsenic ion(As^3-) acquired the electron configuration of krypton and its last shell has eight electrons. Since the last shell of an arsenic ion has eight electrons, the valence electrons of arsenic ions(As^3-) are eight.

What is the valency of arsenic?

The ability of one atom of an element to join another atom during the formation of a molecule is called valency(valence). The number of unpaired electrons in the last orbit of an element is the valency of that element.

Valence is determined from the electron configuration of the element in the excited state. The electron configuration of arsenic(As*) in excited state is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹ 4p_x¹ 4p_y¹ 4p_z¹ 4d_xy¹.

Here, the electron configuration of arsenic shows that five unpaired electrons exist in the last shell. Therefore, the valency of the arsenic atom is 5.

The oxidation state of arsenic is +3. The oxidation state of arsenic +3 has been used in gallium arsenide(GaAs). The valency of arsenic in this compound is 3. The oxidation states of arsenic depend on the bond formation.