1. Basic Chemistry

2. Background Element:Element: a substance that cannot be broken down into simpler chemical substances. 96%96% of the human body is composed of 4 elements: carbon, hydrogen, oxygen, and nitrogen symbolsElements are represented by one to two letter symbols

4. The rest of the human body is composed of trace elements. AtomAtom: smallest particle of an element that has the characteristics of that element.

5. Structure of an Atom Nucleus: center part; contains neutrons and protons Electron Cloud: outer shell of atom; contains electrons

6. Parts of the Atom Proton: positively charged particle Electron: negatively charged particle Neutron: neutral particle

7. Chemistry Vocabulary Isotope: atoms of the same element that have different numbers of neutrons –E–Example: C-12; C-14 Compound: substance that is composed of atoms of two or more different elements that are chemically combined –E–Example: Hydrogen gas Molecule: a group of atoms held together by covalent bonds; has no overall charge. –E–Example: sugars, fats, proteins,

8. Ion: charged particle made of atoms Metabolism: all the chemical reactions that occur within an organism Mixture: a combination of substances in which the individual components retain their own properties Solution: a mixture in which one or more substances (solute) are distributed evenly in another substance (solvent).

9. pH: measure of how acidic or basic a solution is Acid: any substance that forms hydrogen ions in water; pH below 7 Base: any substance that form hydroxide ions in water; pH above 7 Buffer: substance used to minimize the change in pH

10. Organic vs. Inorganic Organic: relating or belonging to the class of chemical compounds having a carbon basis –Important organic substance: carbon Inorganic: Describing a substance not derived from a living organism –Important inorganic substance: water