CH354 Chapter Notes - Chapter 1: Decimal Mark, Significant Figures, Osmium
Document Summary
Matter is made up of very tiny units called atoms, of which we know about 114 types. Each type of atom is the building block of a different chemical element, thus there are 114 elements. 90% of all elements are natural and the remaining percentage of elements is those synthesized in the laboratories. When two or more elements are joined, they form a compound. A molecule is the smallest entity having the same proportions of the constituent atoms as does the compound as a whole. An element and compounds are referred to as substances. When two or more substances mix, they form a mixture. When a mixture is uniform in composition and properties throughout, it is known as a homogeneous mixture or solution (e. g. ordinary air, seawater, and gasoline). When the composition and physical properties vary from one part of the mixture to another, it is known as a heterogeneous mixture (e. g. sand and water).