Chem – Periods, Rows, Columns, and Groups


One immediate division you might have seen on the periodic table is that the elements and their corresponding boxes are organized into vertical (up and down) columns and horizontal (left to right) rows. This link shows a periodic table with the columns (groups) and rows (periods) labeled. You should open that link up and keep it with you to compare with the explanations and examples in this section. In chemistry, we call the vertical organization either columns or groups. Whereas, the horizontal organization is called rows or periods. The columns or groups are usually labeled at the top of the periodic table by numbers; 1 through 18. On they periodic table that you have open one example of a group is group 17. It contains the elements fluorine, chlorine, bromine, iodine, and so on. The periods on most periodic tables are label on the left side of the periodic table by number 1 through 7. On the periodic table you have open one example of is period 4. It contains the elements potassium, calcium, scandium, titanium, and so on. In general, knowing the groups is a lot more important than knowing the periods. A lot of common properties between elements are shared if they are in the same group. For example, fluorine and chlorine are both in the same group and are both gases at a normal room temperature.


Examples: Given the period or group write at least 4 different elements in it.

Group 15 N, P, As, Sb, Bi
Period 3 Na, Mg, Al, Si, P, S, Cl, Ar


PRACTICE PROBLEMS: Given the period or group write at least 4 different elements in it.

Group 13 B, Al, Ga, In, Tl
Group 2 Be, Mg, Ca, Sr, Ba, Ra
Period 2 Li, Be, B, C, N, O, F, Ne
Group 8 Fe, Ru, Ir, Mt
Period 5 Rb, Sr, Y, Zr…Ag, Cd, In, Sn, Sb, Te, I, Xe


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