# What is Atomic Mass

In defining what is atomic mass, the combined weight of protons,neutrons and electrons needs to be considered – this constitutes the mass of an atom ( ma).  The weight of all of these grouped together in a single atom when the atom is motionless constitutes atomic mass. All elements and compounds in atomic masses are different, as they all contain a different number of protons, electrons and neutrons.

Atomic masses are given on a relative atomic mass scale, the masses of all atoms are compared with that of a carbon atom. The relative atomic mass of an atom can therefore be defined as the mass of an atom on a scale where the mass of a carbon atom is twelve units. So to test this out, one atom of carbon is twelve multiplied by the mass of one hydrogen atom (H).

You can determine how many electrons are needed to complete a full ring in the atom by the column in the periodic table where the element is present. Carbon is in group four, meaning it has four electrons on its outer ring, this means that when it bonds through ionic bonding, it will need to take two electrons from another atom. This will give it a negative charge of two, as it has lost the charge when it takes the electrons. Atoms need eight electrons around the outer ring to complete it and to bond.

The atomic structure of an atom can be described using two numbers: the atomic number, the number of protons and the mass number, the number of protons and neutrons.  As mentioned earlier, all atoms are made up of protons, neutrons and electrons; the protons and neutrons are found in the nucleus and the electrons float around shells around the nucleus. All of these put together give you the atomic mass of an element.

When elements and compounds bond, there are two ways for the bonding to occur, covalent bonding and ionic bonding. Ionic bonding involves electron transfer, so, using carbon again, the electrons are transferred to the carbon atom from another element that doesn’t need them. This can only happen between metal and non-metal atoms. The metals lose electrons and form positive ions – meaning both atoms complete their electron shells.

Covalent bonding involves electron sharing instead of electron transfer; instead of a metal and non-metal, both of the atoms are non-metal and this results in the formation of a molecule, but again, both atoms have complete outer shells of electrons and can now have their atomic mass measured.

So, in finding out what atomic mass is, understanding the combined weight of electrons, neutron and protons is important and considering covalent and ionic bonding will aid learning in this scientific sphere.