A system of ideas that explains many related observations and is supported by a large body of evidence collected through scientific investigation is considered a

Theory

Explanation:

Science is empirical in nature. It massively depends on the gathering of a large body of evidence to support one's idea.

In the scientific method, observations are subjected to rigorous experimentation until a large data of empirical evidences support such idea.

When such idea has been supported by massive empirical evidence, we now call it a theory.

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.