the horizontal rows (not groups) are known as periods.
The horizontal rows are called periods, there are 7. The vertical rows are groups and there are 18.
The periodic table is just ONE table. There are not sub-tables. The periodic table is divided into periods (the horizontal rows of the table) and groups (the vertical columns). As you move horizontally across the table, an increase is the atomic number is seen, along with trends in acidity, bonding behavior, and reactivity. The groups are arranged to contain elements that have similar properties. For example, Group 1 is called the alkali earth metals group; all are light, highly reactive metals. Many more trends and groupings exist.
The columns are known as groups.
Because the elements that have similar properties are arranged in groups - or 'periods'.
7The Periodic Table has 7 periods and 18 groups.
There are 18 families. They are made according to the properties of elements. So the elements in a group has similar properties.
Seeing as most periodic tables I use are in black and white, its mostly patterns. Vertical columns share certain properties, horizontal rows share some properties, and the various series are also related.
A group or family is a vertical column in the periodic table. A period is a horizontal row in the Periodic Table. Some groups have specific names also; alkali metals, alkaline earth metals, halogens, pnictogens, chalcogens, and noble gases. However, some other groups, such as group 7, have no trivial names and are referred to simply by their group numbers, since they display fewer similarities and/or vertical trends.
The periodic table has 7 periods and 18 groups. The periods are in a horizontal line and the groups are in a straight line like up to down.
Groups
These chemical elements are called transition metals.
It is arranged such that similar elements with similar preferred bonding arrangements are aligned vertically. This exposes the various s, p, d, and f bonding orbitals for each successive "exterior" shell, and so appears to repeat... hence "periodic".