The world's 92 different kinds of atoms, or elements, are placed in a list called the Periodic Table. This list starts with the lightest and simplest element, hydrogen, and goes to the heaviest, uranium. The atoms' place in this list is called its ATOMIC NUMBER. This video shows all the elements on the Periodic Table, plus some extra ones that clever scientists have made in the laboratory.
Scientists rearranged the list of elements to form The Periodic Table, but still keeping all the elements in their correct weight order, and they placed all the Noble Gases in a vertical column on the extreme right.
They then arranged all the other elements that shared similarities in columns to form 18 vertical groups of elements all with similar properties to each other. Because the Noble Gases was on the extreme right it became Group 18. Group 17 were called the Halogens, group 1 were called the Alkali Metals, and group 2 were called the Alkaline Earth Metals. All the other groups do not have a special name, but they are still nevertheless considered "families" of elements. You can see that the Periodic Table also has 7 horizontal rows. Moving from left to right across a row, the elements move from being very metallic, to less metallic in their properties. A metal is an element that is usually shiny, solid, malleable and can conduct electricity well. The elements on the right hand side of the Periodic Table are non-metals, and are usually gases or liquids, and they cannot conduct electricity at all. The in-between elements (shown in grey cells on the table) are semi-metals and can conduct electricity a little bit. The Periodic Table is called "periodic" because each row repeats this trend from metal to semi-metal to non-metal.