The+Periodic+Table

All the gas based elements are put together like argon and helium into a **group.** Special name for this group **noble gases.** A **period** is a horizontal row, left to right decreasing atomic size and metal to nonmetal.

The Periodic Table of Elements was made by **Dmitri** // **Mendeleev,** a Russian. //

 // The number on the top left is called the **atomic number,** the number under the chemical symbol is the **atomic mass.** //

// **Between the purple and green elements is a zigzag line separating nonmetals(top) from metals(bottom).** //