The Periodic Table
There are about 100 elements in the world. The elements are arranged in a table. The table is known as the periodic table. Going across the rows of the periodic table, atomic weights increase. The columns of the periodic table contain elements with similar chemical properties.
The periodic table has seven rows. The rows are unequal in length. The seven rows contain the following numbers of elements:
2, 8, 8, 18, 18, 32, 23
The numbers 2, 8, 18, and 32 are twice the squares of 1, 2, 3, and 4.
Each element is numbered according to its place in the periodic table. These numbers are the atomic numbers of the elements.