February 7 is National Periodic Table Day. Established in 2016, this day is in recognition of chemistry’s building blocks. The periodic table is credited for all the breakthroughs and advancements made in chemistry. The first periodic table was published on February 7, 1863 by scientist John Newlands. The present-day periodic table was framed by Dmitri Mendeleev in 1869. He was born the day before February 7. It all started back in 1817, when chemists Johann Doberiener and J.J. Berzelius worked together on experiments with hydrogen ignition and potassium powder. This led to Doberiener organizing elements with similar properties into groups of three. The rest, they say, is history. You can learn more about the creation and importance of the periodic table here.
Each element has its own chemical and physical properties. For hundreds of years, Scientists have tried to learn more about the elements by studying their properties. Early scientists knew a little about the mass of atoms. They were able to arrange the elements in order from the atom with least mass to the atom with the most mass. When they looked at this list, they saw something interesting. The properties of the elements repeated every so often. For example, the 4th, 12th, and 20th elements showed the same properties. They arranged the elements in a table that showed how properties repeated. Each time the properties started to repeat, they started a new row of the table. This table is called the periodic table of the elements. Download your own copy of the periodic table here.
Look at the periodic table. Each square has the symbol of a different element. Some of the symbols do not look like the names of the elements. For example, the symbol for gold is “Au”. The numbers in the squares are called atomic numbers. Notice that the numbers get bigger from left to right in each row. The atomic number is equal to the number of protons in the nucleus of each atom of that element. The atomic number is also equal to the number of electrons. So, each element has one more proton and one more electron than the element just before it. Each up-and-down row is called a group. The groups are numbered from 1 to 18 across the top of the table. Take time to study the periodic table and see the patterns for yourself.