The columns of the Periodic Table are called groups and all elements in a group have the same number of electrons in their outer electron shell. The group that an element occupies generally determines its chemical properties as the number of outer shell electrons establishes the way it reacts with other elements to form molecules. So, because each element has the same number of electrons in its outer shell, each has similar reactivity.
Elements in the same group in the Periodic Table of the Elements have the same:
number of electrons in their outer electron shell |
|
number of electrons |
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number of atomic mass units |
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number of electron shells |