Periodic Table is a chart that organizes all known elements into a grid of horizontal row and vertical columns arranged by increasing atomic number.

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Groups

​Groups are the vertical columns of the periodic table. Each representative group has the same number of valence electrons

Periods

​A horizontal row of elements in the modern periodic table. This is equal to the number of energy levels allowed in the atom.

​Valence electrons:

​The electrons in an atom’s outermost orbitals; determine the chemical properties of an element.​

-Each group of representative elements (1,2, 13-18) have an assigned amount of valence electrons.