Why is atomic number important?

Atomic number is one of the most important terms in the science of chemistry. Atomic number refers to numbers of protons in the nucleus of atom, and thanks to this number we can identify each chemical element and learn about its properties.

In chemistry atomic number is known under the symbol Z. Mass number (the total number of protons and neutrons in nucleus) has the symbol A, and this is the main reason why some people tend to mix these two numbers thinking that the symbol for atomic number is A. The number of neutrons in nucleus has symbol N.

The numbers of protons and neutrons doesn't have to be the same in the nucleus of an atom. Atoms that have the same atomic number Z but different neutron number N are known under the name of isotopes.

Atomic number is fundamental part of periodical law and one of the main foundations on which modern chemistry is built upon. The entire periodic table is arranged by means of atomic number because this offers the easiest solution to categorize chemical elements.


Atomic number is also important to determine the chemical properties of certain element. This is because neutral atoms have the same number of protons and electrons, so by knowing the atomic number you also know about the number of electrons, and electrons are the ones that make chemical bonds, therefore determining chemical properties of a given element.

The next time you look at the periodic table you'll know that the number listed for each element is its atomic number (A).

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What is an atom made of?

Atom is really the foundation on which your chemistry knowledge should be built upon. In order to understand the atom you first need to know the answer to the question of what is an atom made of.

The atom is made of nucleus and a lot of empty space. The nucleus, located at the center of the atom contains positively charged protons, neutrons which have no charge at all. The empty space around the nucleus is reserved for negatively charged electrons that are much smaller compared to protons and neutrons (an electron has a mass that is approximately 1/1836 that of the proton).

Protons and neutrons are called nucleons because they are the particles that make up the atomic nucleus. The often used term „nuclear force“ refers to interaction between two and more nucleons. Neutrons are slightly heavier than protons, by approximately 0.1%. Both the proton and neutron are made of three quarks.

Electrons (negatively charged particles) play vital role in phenomena such as electricity and magnetism. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding.

The number of protons in atom is very important because it determines which element it is in a periodic table. Hydrogen, the first element in periodic table has only one proton, carbon for instance is element number 6 in periodic table because it has 6 protons, and so on. The number of protons in each atom is its atomic number. If the atom has no charge then this means there is the same number of protons and electrons in the atom because the same number of positive and negative charges balance each other out.

Atoms are the main building blocks of all matter. Everything around us is is made of atoms, though more precise word in this case is molecule, since atoms when joined together form molecules.

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