Arsenic Protons Neutrons Electrons (And How to Find them?)

Arsenic has 33 protons, 42 neutrons and 33 electrons.

But how will you find the number of protons, neutrons and electrons in Arsenic (As)?

Well, it is very easy to find the protons, neutrons and electrons of arsenic atom.

Here I have given a very simple method for finding the protons, neutrons and electrons of arsenic atom.

Let’s dive right into it!

Finding the Protons, Neutrons and Electrons in Arsenic

How to find protons?

• The number of protons can be found by knowing the atomic number of that atom. ^[1]

How to find neutrons?

• The number of neutrons can be found by subtracting the atomic number from its atomic mass.

How to find electrons?

• For a neutral atom, the number of electrons can be found by knowing the atomic number of that atom.

Let’s calculate the number of protons, neutrons and electrons in arsenic.

#1 Number of Protons in Arsenic

If you have a periodic table with you, then most of the answers are in front of you.

You can see the elements, their atomic number and their atomic mass from the periodic table.

Now here our element is Arsenic (As).

So from the above periodic table, you can see that the atomic number of arsenic is 33.

As the atomic number of arsenic is 33, it has a total of 33 protons in its nucleus.

Thus, the number of protons in Arsenic is 33.

#2 Number of Neutrons in Arsenic

In order to find the number of neutrons of an arsenic atom, you should know its atomic mass first.

The number of neutrons in arsenic can be obtained by subtracting the atomic number from its atomic mass.

The atomic mass of arsenic is 74.922 u (which you can round it to 75). ^[2]

So from this atomic mass (i.e 75), you have to subtract its atomic number (i.e 33).

So you will get 75 – 33 = 42.

Thus, the number of neutrons in Arsenic is 42.

#2 Number of Neutrons in Arsenic

In order to find the number of neutrons of an arsenic atom, you should know its atomic mass first.

The number of neutrons in arsenic can be obtained by subtracting the atomic number from its atomic mass.

For a neutral atom, the number of electrons and the number of protons are the same.

Here, the arsenic atom is a neutral atom.

So the number of electrons in arsenic is equal to its number of protons (which is also equal to its atomic number).

In the beginning, we have found that the number of protons in arsenic is 33.

Thus, the number of electrons in Arsenic is 33.

Summary

Number of Protons in Arsenic

• The number of protons can be found by knowing the atomic number of that atom.
• Number of Protons in Arsenic = Atomic number of Arsenic = 33

Number of Neutrons in Arsenic

• The number of neutrons can be found by subtracting the atomic number from its atomic mass.
• Number of Neutrons in Arsenic = Atomic mass of Arsenic – Atomic number of Arsenic = 75 – 33 = 42

Number of Electrons in Arsenic

• For a neutral atom, the number of electrons can be found by knowing the atomic number of that atom.
• Number of Electrons in Arsenic = Atomic number of Arsenic = 33

I hope you have understood the simple method for finding the protons, neutrons and electrons of arsenic atom.

Check out related topics for more practice;
Selenium protons neutrons electrons
Bromine protons neutrons electrons
Krypton protons neutrons electrons
Indium protons neutrons electrons
Tin protons neutrons electrons