Chapter 2 The Chemistry of Life

Matter-anything that has mass and takes up space –Solid: any substance that has a definite shape and a definite volume –Liquid: has a definite volume but no definite shape –Gas: has no definite volume or shape *Changing states requires adding or removing energy

Physical Changes A physical change is a change in the size, shape, or state of a substance –Ex: melting, freezing, molding clay, cutting wood

Atoms Atoms- the smallest particles that make up all matter –Protons(+): –Protons(+): positively charged particles found in the nucleus of an atom –Neutrons(o): –Neutrons(o): neutral particles found in the nucleus of an atom –Electrons(-): –Electrons(-): negatively charged particles found outside of the nucleus

Model of the Atom

Elements Elements are substances made of only one type of atom –Ex: O 2 (oxygen) H 2 (hydrogen) O 3 (ozone)

Ions Ions are atoms that have lost or gained electrons Ions have a positive(+) or negative(-) charge Na Lose Electron Na + Cl Gain Electron Cl _ Positive ionNegative ion

Compounds & Molecules Compounds and Molecules are formed when 2 or more different elements are bonded together Ex: Compound- Salt(NaCl) Molecule- Water(H 2 O)

Molecular Formulas Molecular formulas show the kind and # of atoms in a molecule –H 2 O = 2 hydrogen atoms + 1 oxygen atom –CO 2 = 1 carbon atom + 2 oxygen atoms –C 6 H 12 O 6 = 6 carbon atoms + 12 hydrogen atoms + 6 oxygen atoms –NaCl = 1 sodium ion(Na) + 1 chlorine ion(Cl)

Chemical Change Chemical change occurs when atoms combine or separate to create new substances Chemical changes use or give off energy Ex: Combustion(burning) C 3 H 8 + O 2  CO 2 + H 2 O propane + oxygen  carbon dioxide + water Ex: Oxidation(rusting) Fe + O 2  Fe 2 O 3 iron + oxygen  ironoxide(rust)

Mixtures A mixture forms when chemicals combine but do not bond –Ex: salt water, salad dressing, chocolate milk Solutions: is a mixture with it’s parts evenly mixed Solute – substance that gets dissolved ex: salt, sugar, chocolate Solvent – substance that dissolves another substance ex: water, milk, alcohol

Bonding Bonding is a force of attraction holding atoms together Types of Bonding: –Covalent Bonds –Ionic Bonds –Hydrogen Bonds

Covalent Bonds Covalent bonds form when 2 or more neutral atoms share electrons to form a molecule –Ex: H 2 O(water) -Ex: CO 2 (carbon dioxide)

Ionic Bonds Ionic bonds form when 2 or more ions become held together by their opposite charges Ex: NaCl(salt) –Positive ions are attracted to negative ions

Hydrogen Bonds Hydrogen bonds hold together water molecules

Cohesion & Adhesion Cohesion- the attraction between molecules of the same kind –Ex: water forms droplets, surface tension Adhesion- the attraction between different substances –Ex: water drops stick to leaves and skin

Cohesion & Adhesion

Acids & Bases Acids- contain large amounts of hydrogen(H + ) ions –Acids turn pH paper RED Ex: stomach acid(HCl), vinegar, citric acid Bases- contain large amounts of hydroxide(OH - ) ions –Bases turn pH paper BLUE Ex: bleach, ammonia, soap

Neutral Substances Neutral substances have equal amounts of hydrogen(H + ) and hydroxide(OH - ) ions Ex: water (H 2 O), alcohol (C 2 H 5 OH), oil - neutral substances do not change pH paper

Types of Compounds Inorganic- come from non-living things, do not contain carbon Ex: Salt (NaCl) – sodium chloride Water (H 2 O) Organic- come from living things and contain carbon Ex: Carbohydrates, Fats, Proteins, Nucleic Acids

Carbohydrates Used for Short Term energy Contain: carbon(C), Hydrogen(H), oxygen(O) Ex: sugars- glucose, sucrose, fructose starches- bread, pasta, potatoes Glucose - C 6 H 12 O 6

Fats & Lipids Used for Long Term energy storage Contain: carbon(C), hydrogen(H), oxygen(O) Ex: fats, oils, waxes

Proteins Used to Build and Repair body tissues Contain: carbon(C), hydrogen(H), oxygen(O), & nitrogen(N) Proteins are made from amino acids

Nucleic Acids Used to make DNA Contain: carbon(C), hydrogen(H), oxygen(O), nitrogen(N), & phosphorus(P)

Enzymes Enzymes are a special type of protein used to perform chemical reactions within the body Certain enzymes build new molecules and others break down molecules within the body

Enzymes Enzymes bind to a substrate with a matching active site

END OF CHAPTER 2 NOTES!!!