Question

How do atomic masses vary throughout the periodic table?

Answer 1

As we know that the periodic table contains a trend for every parameter like atomic number, electronegativity, ionisation enthalpy, electron gain enthalpy etc. which increases or decreases down the group or while moving from left to bottom.

Complete step-by-step answer:
As we know that a lot of trends are there in the physical and chemical properties of elements. So, let us talk about one of the trends observed for the Atomic masses is defined as the sum of the total number of protons and neutrons of an atom. And the atomic mass on moving from left to right in the periodic table increases because the more protons and neutrons are added to the nuclei of an atom.

Atomic mass of an atom also increases while moving from top to bottom because the atoms in the rows, on further moving down, have more protons and nucleons. Thus, we can say that when we move down a group in case of non-metals, the reactivity of elements decreases while moving from left to right it increases in case of metals.

Also, the atomic mass of the element actually uses average atomic masses of elements because naturally occurring elements exist as more than one isotopes which are the atoms of the same element which possess different relative masses.

Note: Remember that the atomic masses which are mentioned in the periodic table of elements for different elements actually represent their average atomic masses. And atomic mass always increases in a period or a group.