Columns in the periodic table are called groups, and the rows are called periods. Notice that the groups are labeled 1 to 18 and the periods are labeled 1 to 7. Groups 1, 2, and 13 to 18 are called the main group elements, groups 3 to 12 are the transition elements, and the bottom two rows are called the lanthanides and actinides, respectively.
This table gives properties and alternate names for some of the groups:
Group Name Properties
1 Alkali metals React to form 1+ ions.
2 Alkaline earths React to form 2+ ions.
17 Halogens React to form 1 ions.
18 Rare gases(noble gases) Stable and unreactive. (Elements from other
groups form ions to achieve the same number
of electrons as a noble gas.)
i) What is the atomic number of the element located in group 16, period 2 of the periodic table? Enter the atomic number.
ii) If a new element were discovered and it was found to form 1 ions, in which group would you place it in the periodic table? Enter the group number.