The Periodic Table

The periodic table is a system which helps to classify the elements.

In 1735 there were only 13 known elements.

In 1815 there were 47.

Today there are over 100 including several man-made elements.

The periodic table that we use today was devised by a Russian scientist named Dmitri Mendeleev in 1886

Using his model, he was able to predict the properties of missing elements before their actual discovery took place.

The periodic table can tell us many things, elements are arranged in order of their atomic numbers.

The atomic number is based on the number of protons in the atom. A proton is a very small part of an atom that has a positive charge.

The atomic weight/mass of an element and symbol are also given.This is the average mass of the element based on atomic mass units (AMUs)

The atomic weight/mass of an element and symbol are also given

One AMU is equal to one twelfth (1/12) of the mass of carbon.

This is Carbon and Iron.

The horizontal rows in the periodic table are called periods.

The vertical columns are called groups.

All elements in the same group have similar characteristics. For example the last group – helium, neon, argon, krypton, xenon and radon are inactive gases