APA citation style: Historic American Buildings Survey, C. & Benison, G. (1933) Oakland Plantation, Mount Pleasant, Charleston County, SC. Documentation Compiled After. [Pdf] Retrieved from the Library of Congress, https://www.loc.gov/item/sc0292/.
There are 18 groups (columns) in the periodic table. Group 1 (also known as the alkali metals) is the column on the far left of the table. Elements in the same group have similar, but not identical characteristics. This is because they all have the same number of electrons in their outermost shell.
When you look at the periodic table, it is very apparent that the elements have been organized into some kind of order, in rows and columns. The first and most important division within the table is the individual columns, known as Groups or Families. Let's take a tour of the different groups one at a time.