The atomic mass number is equal to the number of protons plus neutrons. This number is typically found beneath the element symbol. Atoms with the same atomic number, but different mass numbers are called Isotopes. Below is a diagram of a typical cell on the periodic table. Groups are the vertical columns which include elements with similar chemical and physical properties.
Periods are the horizontal rows.
Going from left to right on the periodic table, you will find metals, then metalloids, and finally nonmetals. The 4th, 5th, and 6th periods are called the transition metals. These elements are all metals and can be found pure in nature. They are known for their beauty and durability. The transition metals include two periods known as the lanthanides and the actinides which are located at the very bottom of the periodic table.