Matter Definition, Classification, and the Periodic Table

Matter is commonly defined as anything that occupies space and has mass. All matter is made up of tiny particles called atoms. An atom is the smallest particle of an element. 

One of the milestones in the study of matter was the theory pubUshed by English chemist John Dalton (1766-1844) in 1803, now commonly known as the Dalton s atomic theory. Dalton postulated that all matter could be described according to the following rules  

Elements with similar properties such as comparable atomic radius are placed in the same columns called groups or families (1-8 or 1-18). Because of their similar properties, four main regions in the periodic table can be distinguished  

TABLE 4.1. Some Good, Bad, and Ugly Common Elements 

Nitrogen and explosives Lead and paint Arsenic and poisoning 

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