Oxygen is a classified nonmetallic element and its symbol is O. Oxygen is the 8th element of the periodic table so its atomic number is 8.
The atomic number of an element is equal to the number of protons and electrons in that element. Therefore, an oxygen atom has eight protons and eight electrons.
The number of neutrons in an atom can be determined by the difference between the atomic mass and the number of protons.
The difference between the mass number of the oxygen atom and the number of protons is eight. Therefore, an oxygen atom has eight neutrons.
The number of neutrons depends on the isotope of the element. The oxygen atom has three stable isotopes.
Element Name | Oxygen |
Symbol | O |
Atomic number | 8 |
Atomic weight (average) | 15.999 |
Protons | 8 |
Neutrons | 8 |
Electrons | 8 |
Group | 16 |
Period | 2 |
Block | p-block |
Electrons per shell | 2, 6 |
Electron configuration | [He] 2s22p4 |
Oxidation states | -2 |
This article discussed in detail how to easily find the number of protons, neutrons, and electrons in an oxygen atom.
Also discussed is the position of electrons, protons, and neutrons in an atom, the number of atomic masses, and the isotopes of oxygen. Hopefully, after reading this article you will know the details about this topic.
Where are the electrons, protons and neutrons located in an atom?
An atom is the smallest particle of an element that has no independent existence but is directly involved in chemical reactions as the smallest unit. Atoms are so small particles that they cannot be seen even under a powerful microscope.
The diameter of anatom of hydrogenis 0.1nm (1.0nm = 10-9m). So, if 1000 crore atoms of hydrogen are arranged side by side, it will be 1 meter long.

However, it has been possible to detect atoms by increasing the vision of a very powerful electron microscope by two million times. Numerous permanent and temporary particles exist in the atom.
Electrons, protons, and neutrons are located in the atom as permanent particles. Also, neutrino, antineutrino, positron, and mason are located in an atom as temporary particles.
Atoms can usually be divided into two parts. One is the nucleus and the other is the orbit. Experiments by various scientists have shown that the nucleus of an atom contains protons and neutrons.
The only exception ishydrogen, which has only protons in its nucleus but no neutrons. Electrons revolve around the nucleus in a specific orbit.
How to easily find the number of electrons, protons and neutrons in an oxygen atom?
Scientist Henry Gwynn Jefferies Mosle examined the X-ray spectrum of various elements in 1913-to 1914. The results of his experiments show that each element has a unique integer equal to the number of positive charges in the nucleus of that element.
He called that number the order of the atoms. Thus, the number of positive charges present in the nucleus of an element is called the atomic number of that element. The atomic number of the element is expressed by ‘Z’.
This number is equal to the serial number of the periodic table. We know that protons are located in the nucleus of an atom as a positive charge. That is, the atomic number is the total number of protons.
The atom is overall charge neutral. Therefore, the number of negatively charged electrons orbiting in its orbit is equal to the number of positively charged protons in the nucleus.
Atomic number (Z) = Number of charges in the nucleus (p)
How many protons does an oxygen atom have?
Protons are the permanent core particles of an atom. It resides in the center or nucleus of the atom. Whena hydrogen atomremoves an electron from its orbit, the positively charged particle that remains is called proton. Hence, the proton is expressed by H+.
The relative mass of protons is 1, which is approximately equal to the mass of hydrogen (1.00757 amu). However, the actual mass of the proton is 1.6726 × 10−27kg. That is, the mass of a proton is approximately 1837 times greater than the mass of an electron.
Proton is a positively charged particle. Its actual charge is +1.602 × 10−19coulombs. The diameter of a proton particle is about 2.4 × 10−13cm.
There are 118 elements in the periodic table and the 8th of these elements is oxygen. The elements in the periodic table are arranged according to their atomic number. Since oxygen is the 8th element of the periodic table, the atomic number of oxygen is 8.
We must always remember that the atomic number and the number of protons of an element are equal. Therefore, an oxygen atom contains eight protons.
How many electrons does an oxygen atom have?
Electrons are the permanent core particles of an atom. It resides in a specific orbit of the atom and revolves around the nucleus. The properties of the elements and their compounds depend on theelectron configuration.
In 1897, scientist J. J. Thomson discovered the existence of electrons through cathode ray examination. The smallest of the permanent core particles of an atom is the electron. Its mass is about 1/1836 of the mass of a hydrogen atom.
The actual mass of the electron is 9.1085 × 10−28g or 9.1093 × 10−31kg. The mass of the electron is often ignored because this mass is too small. Electrons always provide a negative charge.

It is expressed by e–. The charge of electrons is –1.609 × 10–19coulombs and the relative charge is –1. That is, the charge of an electron is equal to that of a proton but the opposite.
We must also remember that the number of protons and electrons in an element is equal. Therefore, an oxygen atom contains eight electrons in its orbit.
How many neutrons does an oxygen atom have?
Scientist Chadwick discovered neutrons in 1932. It is located in the nucleus at the center of the atom. The neutron is a charge-neutral particle and it is expressed by n.
The charge of a neutron is zero and the relative charge is also zero. The mass of the neutron is 1.674 × 10−27kg. The number of electrons and protons in an atom is the same but the number of neutrons is different.
We already know that the nucleus is at the center of the atom. There are two types of particles in the nucleus. One is a positively charged particle proton and the other is a charge-neutral particle neutron.
Almost all the mass of the atom is accumulated in the nucleus. Therefore, the mass of the nucleus is called atomic mass. The nucleus is made up of protons and neutrons. Therefore, atomic mass refers to the total mass of protons and neutrons.
Atomic mass (A) = Nucleus mass = Total mass of protons and neutrons (p + n)
Again, the mass of each proton and neutron is about 1amu. Therefore, the total number of protons and neutrons is called the atomic mass number. That is, the number of atomic mass(A) is = p + n
Thus, the number of neutrons in an element is obtained from the difference between the number of atomic masses and the number of atoms. That is, neutron number (n) = atomic mass number (A) – atomic number (Z)
Mass number (A) | Atomic number (Z) | Neutron number = A – Z |
16 (15.999) | 8 | 8 |
We know that the atomic number of oxygen is 8 and the atomic mass number is about 16. Neutron = 16 – 8 = 8. Therefore, an oxygen atom has eight neutrons.
Based on the atomic number, mass number, and neutron number of the element, three things can be considered. These are isotope, isobar, and isotone. The number of neutrons depends on the isotope of the atom.
How to determine the number of neutrons through isotopes of oxygen?
Atoms that have the same number of protons but different mass numbers are called isotopes of each other. The English chemist Frederick Sodi first came up with the idea of isotopes in 1912, and the scientist Aston in 1919 identified two different massneon atoms(20Ne,22Ne).
He named the atoms with different masses of the same element as isotopes of that element. The number of protons in an isotope atom does not change but the number of neutrons does.
The oxygen atom has more than eighteen isotopes. Such as 11O, 12O, 13O, 14O, 15O, 16O, 17O, 18O, 19O, 20O, 21O, 22O, 23O, 24O, 25O, 26O, 27O and 28O.
Isotope | Mass number (A) | Atomic number (Z) | Neutron number = A – Z |
11O | 11.051250 | 8 | 3 |
12O | 12.034368 | 8 | 4 |
13O | 13.024815 | 8 | 5 |
14O | 14.00859670 | 8 | 6 |
15O | 15.0030656 | 8 | 7 |
16O | 15.994914619 | 8 | 8 |
17O | 16.999131755 | 8 | 9 |
18O | 17.999159612 | 8 | 10 |
19O | 19.0035780 | 8 | 11 |
20O | 20.0040754 | 8 | 12 |
21O | 21.008655 | 8 | 13 |
22O | 22.009970 | 8 | 14 |
23O | 23.015700 | 8 | 15 |
24O | 24.019860 | 8 | 16 |
25O | 25.029340 | 8 | 17 |
26O | 26.037210 | 8 | 18 |
27O | 27.047960 | 8 | 19 |
28O | 28.055910 | 8 | 20 |
Among the isotopes, 16O, 17O, and 18O are stable and are formed naturally. The remaining isotopes of oxygen are highly unstable and their half-lives are very short.
Of the 18 radioisotopes of oxygen, the longest-lived radioisotope is 15O with a half-life of 122.266 sec, while the shortest-lived isotope is 11O with a half-life of 198 ys. The mass of stable 16O is about 16, 17O is about 17, and 18O is about 18.
How many protons, neutrons and electrons does oxide ion(O2–) have?
When an atom carries a negative or positive charge by accepting or rejecting electrons, it is called an ion. The ionic properties of the elements depend on the exchange of electrons.
In an atomic ion only the number of electrons changes but the number of protons and neutrons does not change. Oxygen has six electrons in its last orbit.

The last shell of an oxygen atom receives two electrons and turns into an oxide ion(O2–). In this case, the oxygen atom carries a negative charge.
O + 2e– → O2–
Here, the electron configuration of oxide ion(O2–) is 1s2 2s2 2p6. This negative oxide ion(O2–) has eight protons, eight neutrons, and ten electrons.
Oxygen Ion | Protons | Neutrons | Electrons |
O2– | 8 | 8 | 10 |
What are the properties of protons neutrons and electrons?
Name | Symbol | Relative Mass (amu) | Relative Charge | Actual Mass(kg) | Actual Charge(C) | Location |
Proton | p | 1.00757 | +1 | 1.672×10−27 | 1.602×10−19 | Inside the nucleus |
Neutron | n | 1.0089 | 0 | 1.674×10−27 | 0 | Inside the nucleus |
Electron | e– | 5.488×10−4 | –1 | 9.109×10−31 | –1.6×10–19 | Outside the nucleus |
Why is it important for us to know the number of electrons and protons?
Atomic number is a number that carries the properties of an element. The number of electrons and protons in an element is determined by the atomic number. Also, the exact position of an element is determined in the periodic table.
The properties of an element can be determined by electron configuration. Also, the valency,valence electrons, and ionic properties of the elements are determined by the electron configuration.
To determine the properties of an element, it is necessary to arrange the electrons of that element. And to arrange the electrons, you must know the number of electrons in that element.
To know the number of electrons, you need to know the atomic number of that element. We know that an equal number of protons of atomic number are located in the nucleus of the element and electrons equal to protons are in orbit outside the nucleus.
Atomic number (Z) = Number of electrons
We know that the atomic number of oxygen is 8. So, there are eight electrons in the atom of the oxygen element. That is, it is possible to determine the properties of oxygen from the electron configuration.
Now, the electron configuration of oxygen shows that the last orbit has six electrons. Therefore, the valence electrons of oxygen are six. The last shell of oxygen has two unpaired electrons, so the valency of oxygen is 2.
The last electron of oxygen enters the p-orbital. Therefore, it’s a p-block element. To know these properties of oxygen one must know the number of electrons and protons of oxygen.
Reference
FAQs
Protons, Neutrons, Electrons for Oxygen (O, O2–)? ›
Number of electrons in O2 = 8 + 8 = 16. In O2+, the number of electrons is 16 – 1 = 15.
How many electrons does O2+ have? ›Number of electrons in O2 = 8 + 8 = 16. In O2+, the number of electrons is 16 – 1 = 15.
How many protons and electrons are present in O2 − 2 −? ›Answer and Explanation:
Oxygen (O) is an element with the atomic number of 8. Therefore, every oxygen atom will contain 8 protons. The charge on this simple anion is -2, which implies an excess of 2 electrons. Therefore, this simple anion contains a total of 10 electrons.
Oxygen atom has 8 electrons, 8 protons and 8 neutrons.
What are the bond orders for O2+ O2 and O2 −? ›O2+ and O22- is O22- < O2- < O2 < O2+. The total number of covalently bound electron pairs between two atoms in a molecule determines the bond order of a covalent bond.
How many unpaired electrons are in O2 O2+ O2? ›O2 has 2 unpaired has electron white O+2 and O−2 have one each unpaired electron and O2+2 does not have any unpaired electron .