Chemistry of Life Matter-anything that occupies space and has mass Mass -quantity of matter an object has Weight -force produced by gravity acting on mass Atom Element -simplest particle of an element; determines structure & properties of matter -substance that cannot be broken down chemically

Interpreting the Periodic Table Chemical Symbol Atomic Number Atomic Mass proton neutron nucleus electron (e - ) -# of protons -# of protons + # of neutrons -positive charge -no charge -central region, made up of protons and neutrons -negative charge, same # as protons, very little mass, located in orbitals

 most atoms are not stable, tend to react with other atoms  isotopes  compounds -are atoms of the same element that have a different amount of neutrons -have different masses -are made up of atoms of 2 or elements in fixed proportions

Chemical Bonds -attractive forces that hold atoms together Covalent Bonds -2 atoms share one or more pairs of electrons Ex. H 2 O molecule –simplest part of a substance that retains the properties of that compound or element

Chemical Bonds continued… Ionic Bonds -bond between two ions with opposite charges ion -an atom or molecule with an electrical charge by either gaining or losing an e - Ex. NaCl, Na + Cl -

-ability to do work -can be neither created nor destroyed -ex. chemical, thermal, electrical, mechanical States of matter Energy

Chemical Reaction -1 or more substances change to produce 1 or more substances -energy is absorbed or released when chemical bonds change CO 2 + H 2 O  H 2 CO 3 Reactants  Product(s) Metabolism – all chemical reactions that occur in a living organism

Activation Energy -the amount of energy needed to start a reaction; usually a large amount Catalyst-chemical substances that reduce the amount of activation energy needed for a reaction Enzyme -a protein or RNA molecule that speeds up metabolic reactions without being permanently changed or destroyed; can function within narrow range

Polar Compound Non-Polar Compound -uneven distribution of charge -even distribution of charge o 2 polar compounds have stronger covalent bond than a polar bonded with a non-polar compound Ex. H 2 O

Hydrogen Bond –force of attraction between H molecules Cohesion Adhesion -attractive force between same substance -attractive force between different substances pH Scale -potential of Hydrogen -measures the acidity and alkalinity -ranges from 0 to 14; 0 very acidic, 14 very basic, 7 neutral Ex. Surface tension Ex. Water molecules and glass molecules

Acids -# of H 3 O - greater than OH - -Sour taste Hydroxide ion: OH - Hydronium ion: H 3 O + Bases -# of H 3 O - less than OH - -Bitter taste Buffer -helps control pH levels -neutralize small amounts of acids/bases