The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...

There are 118 elements in the periodic table, each with a unique symbol and atomic number. Symbol: A one or two-letter abbreviation used to represent the element. Atomic number: The number of ...

The atomic number is shown below the chemical symbol, and the mass number is shown above. In this example the atomic number is 17 and the mass number is 35. This means that each of these atoms has: ...