How we find groups and periods in chemistry

1.	How we find groups and periods in chemistry
Answer» If electrons have 3 valency then 10+3=13 Groups means vertical.... Periods mean horizontal DirectionsIn groups-------->In periods direction towards down Vartical columns called "groups\'\' and horizontal rows called " Period\'\'. Number of shells is equal to the number of periods and electrons in the last shell gives us the group number. If the electron in last shell is less than 3 then it\'s group number is same but if it is more than 3 then v have to add 10 to it to get group number

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