Atomic Number of the Elements


The atomic number of the elements provides information on the number of protons in the nucleus.

The periodic table as laid out by Dimitri Mendeleev, the founding father of the periodic table is based on a key concept that everything relates to the mass of the atom. Dimitri Mendeleev initially began by structuring the periodic table based on the different elements' chemical properties, much as it still is today but a key concept underpinning the periodic table is Atomic Number. The atomic number of an element links back to the mass of a proton. As we say that a proton has a mass of 1 for every proton we have in the nucleus this corresponds to an increase in a. mass of 1.

For example the atomic number of Beryllium is 4 as it has 4 protons in the nucleus each worth a mass unit of 1. If we looked at the atomic mass of Beryllium considering the real mass of a proton (1.672622x10-27 Kg) the actual atomic mass would be 9.012182 x10 -27 Kg when considering the mass of protons in Kg. This is compared to Hydrogen that. has one proton in the nucleus and would have a mass of 1.672622x10-27 Kg.

Every element has a different number of protons in the nucleus. This is what determines what element it is. For example, Carbon has 6 protons and Chlorine has 17. This difference in the number of protons means not only are they different elements but they are at different places in the periodic table. A key trend in the periodic table is its ascending number of protons from left to right, going across the periods. And as you progress down the periodic table the atomic numbers also increase. This means as we progress along a period (from side to side) or down a group (up and down) the atoms get progressively larger usually by a unit of one. This is because a proton is added to the nucleus each time. This is a natural phenomenon, when the universe first began stars were areas of high gravity, heat and force. Under these conditions it is possible to undergo nuclear fusion, adding nucleuses together to increase the number of protons and neutrons. The universe began with simple elements like hydrogen and helium that under high heat and pressure were forced together binding their protons and neutrons with a strong nuclear force.

Terms in section

A neutron is a neutral sub atomic particle that makes up the nucleus with the proton


A proton is a positive particle that makes up the atom in the nucleus with a positive charge

Strong nuclear force

The strong nuclear force is the attractive force between protons and neutrons that keeps them together in the nucleus


The nucleus is the term given to the centre of the atom comprising of the proton and neutron

Atomic number

Atomic number is the number of protons in the nucleus


Mass is the amount of substance that can be measured in grams or kilograms

Chemical properties

Chemical properties are the properties of how the element or compound reacts with other elements and compounds. Such as will it give off heat or light when it reacts.

Dimitri Mendeleev

Dmitri Mendeleev was a Russian scientist who in 1869 proposed the first structure of the periodic table


Chemical Properties


Atomic Mass of the Elements