The periodic table of chemical elements includes all of the currently known elements and provides basic information for each of them. All elements are consequently arranged from left side to right, as well as from top to bottom; their order is determined by an increasing atomic number. Generally, the order also coincides with ascending atomic mass.
Each row of the Table is called a period. Each element’s period number signifies the highest level of energy occupied by an electron in this element (with its state being unexcited). As you look down the table, you’ll notice that numbers of the electrons increase. Thus, as long as the level of an atom’s energy increases, the number of sub-levels in each energy level ascends as well.
Elements that belong to the same column on the table (known as a “group”) get identical electron valance configurations and behave in the same way chemically. For example, in this interactive model of the Periodic Table, you can see that all elements of group 2 are alkaline earth metals.
Who Invented the Periodic Table?
A prominent inventor and chemist from Russia, Dmitri Mendeleev, is called the “father” of the periodic table of elements. Being a lecturer, in the 1860’s he decided to write a textbook in Russian on organic chemistry, which would help to sort out the disordered chemical elements. Depending on the earlier discoveries of other scientists, in 1869 Mendeleev came up with the periodic table acknowledged by the world’s scientific community.
The elements on Mendeleev’s table were arranged according to both valance and atomic weight. Although almost half of the elements were not yet discovered, they later were added in slots left empty by Mendeleev.
How Do We Read the Table?
On the periodic table, you can find information on the elements’…
- atomic number: the number of protons in an element’s atom that defines its identity and determines its behavior.
- atomic/element symbol: an international abbreviation which represents each element (g., “Ca” for calcium or “Al” for Aluminium).
- atomic weight: the average value of an element’s mass, measured in AMU – atomic mass units.