What is periodic table?
Answers
Periodic table:
The Periodic Table is how scientists have organised the 100+ elements that make up all matter.
It was proposed in 1869 by Russian chemist, Dmitri Mendeleev.
Mendeleev arranged the elements in order of the mass of their electrons.
He also left gaps for elements that had not yet been discovered.
This allowed him to predict what those undiscovered elements would be like.
The periodic table arranges the elements in two ways:
Periods: these go across the table from left to right.
As you move in this direction, the number of protons in the nucleus of the atom increases by 1.
Groups: each vertical column is a group.
Groups contain elements with the same kind of properties, because they usually have the same number of electrons in their outer shell.
The charts of elements arranged in a systematic order of increasing order of atomic weight or atomic number is called periodic table.