At present, 118 elements are known to us. All these have different properties. Out of these 118, only 94 are naturally occurring. As different elements were being discovered, scientists gathered more and more information about the properties of these elements.
The modern table is based on Mendeleev’s table, except the modern table arranges the elements by increasing atomic number instead of atomic mass. The atomic number is the number of protons in an atom, which is unique for each element. The modern table has more elements than Mendeleev’s table because many elements have been discovered since Mendeleev’s time.
- Elements in the same group will have the same valence electron configuration and hence, similar chemical properties.
- Elements in the same period will have an increasing order of valence electrons. Therefore, as the energy level of the atom increases, the number of energy sub-levels per energy level increases.
- Dimitri Mendeleev put forward his periodic table based on some scientists’ findings before him, like John Newlands and Antoine-Laurent de Lavoisier. However, Mendeleev is given sole credit for his development of the periodic table.