2-2: ENERGY  Energy (nrg) – the ability to do work or cause change The amount of energy in the universe stays the same but energy can change forms  Types of nrg: Chemical Thermal Electrical Mechanical Ex. Electrical Radiant (light) + thermal (heat)

Energy in Living things  Free energy – energy available to fuel cell processes Ex. Breakfast/Lunch/Dinner  Food (chemical) Work (thermal)

States of Matter  State – rate at which atoms or molecules move

 Solid –tightly packed - particles move slow; definite shape + volume  Liquid – particles move faster; definite volume, no definite shape (takes shape of container)  Gas – particles move the fastest – no attraction to one another: no definite shape or volume

Chemical Reactions (rxns)  Living things undergo 1,000’s of chemical reactions to survive  Chemical reaction = an equation Ex. CO 2 + H 2 O H 2 CO 3 Reactants - CO 2 + H 2 O Products - H 2 CO 3 Two-way arrow means the rxn can go either direction

NRG Transfer  Main source of nrg – FOOD Breakdown sugar to CO 2 + H 2 O, nrg gets released  Exergonic Reactions – net release of free energy A + BC + nrg  Endergonic Reactions – net absorption of free energy A + B + nrgC

Exergonic Reaction

Endergonic Reaction

Activation Energy  Activation nrg  Activation nrg – nrg needed to start a chemical rxn In order for rxns to happen quickly in body, catalysts are used to speed up chemical rxns Catalysts lower the Activation nrg Example:  Enzymes  Enzymes – 1,000s in body; each for different rxns

Reduction-Oxidation Reactions  REDOX- involve transfer of electrons (e-) between atoms  Oxidation – reactant loses e- ~ ”+” charge - - Na Na +  Reduction – reactant gains e- ~ “-” charge - - ClCl -

Another example… CO 2 + H 2 CO + H 2 O How do we know electrons have been transferred?  Because H combined w/ O

Redox (cont.)  Redox rxns always occur together!!!  OILRIG “OIL” – Oxidation is Loss (of e-) “RIG” – Reduction is Gain (of e-)  LEO says GER Loss of e - is Oxidation Gain of e - is Reduction