2 Compounds and BondingPage 145Compound- a substance that is composed of atoms of two or more different elements that are chemically combined
3 Most elements in nature are found combined in the form of compounds How and why do atoms combine?Combine when the resulting compound is more stable than the individual atoms.For many elements, an atom becomes more stable when its outermost energy level is full- by sharing electrons with other atoms
5 Page 146Covalent bond- force that holds atoms together when they are sharing electronsMost compounds in organisms have covalent bonds.
6 Molecule A group of atoms held together by covalent bonds. No overall chargeExample-molecule of water
7 Chemical formula Page 147 Use the chemical symbol for atoms Subscripts represent the number of atoms presentExample:
8 Ionic BondsAn atom gains or loses electrons, it has an electrical charge (charged particle) and will assume the name ION.atoms combine with each other by gaining or losing electrons in their outer energy levels- not sharing of electronsExample page 147- sodium chloride
9 Chemical Reactions Page 147 Occur when bonds are formed or broken, causing substances to recombine into different substancesAll of the chemical reactions that occur within an organism are referred to as that organism’s metabolismConsists of reactants and products
10 Chemical Equations Reactants Products Number before each formula indicates the number of molecules of each substanceSubscripts in a formula indicate the number of atoms of each element in a molecule of the substanceEquations must always balance
22 BIG PICTUREAn acid is any substance that form hydrogen ions (H+) in waterA base is any substance that forms hydroxide ions (OH-) in waterMini lab 6.1
23 LAB- Analysis Questions 1. What would happen to our bodies if blood pH was changed or altered?2. The pH of stomach acid is 2, why is this both good but possibly destructive to our bodies?3. What could happen to our local environment if a company pumped materials into the atmosphere which created a drastic pH change in the rain water?