The Periodic Table: Families and Periods. In the periodic table of elements, there are seven horizontal rows of elements called periods. The vertical columns of elements are called groups, or families. (See also The Periodic Table: Metals, Nonmetals, and Metalloids.)
Then, what do the rows mean in the periodic table?
The periodic table has rows and columns, and they each mean something different. When a column goes from top to bottom, it's called a group. The elements in a group have the same number of electrons in their outer orbital. Those outer electrons are also called valence electrons.
What do the rows on the periodic table represent?
When you look at the periodic table, each row is called a period (Get it? All of the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons.
How are the rows of the periodic table arranged?
The periodic table is a tabular arrangement of the chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties, whose structure shows periodic trends.