Everything we can see and touch, and quite a lot that we can’t as well, is made of tiny particles called atoms. Some substances, like particles of this iron, contain only one kind of atom. Iron is an ...

Chemical reactions occur when elements or compounds combine and create new compounds. Elements are substances that contain only one type of atom and are represented by unique symbols on the periodic ...

1. Some Basic Concepts in Chemistry: Matter and its nature, Dalton’s atomic theory; concept of atom, molecule, element and compound; physical quantities and their measurements in chemistry, precision ...