ERSC 2220H Lecture Notes - Lecture 2: Ionic Compound, Atomic Number, Human Body
28 Oct 2016
School
Department
Course
Professor
Document Summary
Ersc 2220 lecture 2 elements and compounds. Element: the most basic form of matter that exists under ordinary circumstances. Compound: a unique substance that is composed of two or more elements that are chemically combined. Only a few elements are found in their free state (not combined with other elements) Earth has 88 elements present in measurable amounts: 10 constitute <99% of the crust. 118 known elements: 26 spontaneously decompose into other elements. Human body is 93% carbon, hydrogen, and oxygen. Matter is made up of small indivisible particles called atoms. Atoms of the same element are identical and have the same properties: except in the case of isotopes. Chemical compounds are composed of atoms of different elements combined in small whole number ratios. Chemical reactions are merely the rearrangement of atoms into different combinations. Atoms are the smallest fundamental particle of an element that has the porperties of that element.
