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Chapter 2 chemistry of Life Atoms • *Atom is the fundamental unit of matter. • *Can only be seen with an electron microscope. • *Backed by research, fact, and experimentation. Parts of the atom include • Nucleus- has two sub atomic particles -Proton and neutron -Proton has a positive charge -Neutron has no electrical charge • Electrons circle the nucleus and have a negative charge • Elements- these are substances that cannot be broken down chemically into simpler substances. Elements • 92 naturally occurring elements • Only six are abundant in living things Carbon Hydrogen Nitrogen Oxygen Phosphorus Sulfur CHNOPS Isotopes- an atom of an element that has a different number of neutrons than other atoms of that element • *most elements have two or more isotopes • The average mass of all of an elements isotopes is the atomic mass of the element which is listed on the periodic table • Radioisotopes- radioactive isotopes that release radiation that is valuable in experimentation. Compounds- consist of atoms of two or more elements • Example: Water contains two Hydrogen molecules and one Oxygen molecule Compounds- consist of atoms of two or more elements • Example: Water contains two Hydrogen molecules and one Oxygen molecule • H2O two gas elements combine to form a liquid. Compounds- consist of atoms of two or more elements • Example: Water contains two Hydrogen molecules and one Oxygen molecule • H2O two gas elements combine to form a liquid. • NaCl two deadly elements combine to form table salt. Ionic Bonds- A bond formed by the electrical attraction between two oppositely charged ions. • • • • • -one positive and one negatively charged ion -one electron is given from one atom to the other atom ion- an atom with an electrical charge -This is cause when an electron is either given away or received from another atom. Example: NaCl Covalent Bonds- Forms when two atoms share one or more pairs of electrons. • Example: Water Why is this important in Biology? The BIG picture. Why do we study atomic structure in Biology?