CHEM 121 Lecture 2: Chapter 1 Notes
Document Summary
The study of matter and the changes it undergoes. Matter is anything that has mass and takes up space. A compound is a pure substance composed of two or more elements chemically united in fixed proportions. Chemical means must be used to break a compound into its elements. An element cannot be separated into simpler substances by chemical means. 90 elements occur naturally: gold, aluminum, lead, oxygen, carbon. 28 elements have been created by scientists: technetium, americium, seaborgium. Element names have a variety of modern and ancient roots. Element symbols are deri(cid:448)ed fro(cid:373) (cid:374)a(cid:373)es . (cid:271)ut (cid:374)ot al(cid:449)a(cid:455)s a (cid:272)o(cid:373)(cid:373)o(cid:374) name. * copper was the first element ever known and found. Periods (rows) go across the table from the left to the right. Groups share common behavior and go from the top to the bottom. Prefer to gain electrons: noble gases (8a, halogens (7a)-extremely reactive. Prefer to lose electrons: alkali metals (1a)
