Chapter 2: Chemistry of Living Things

-Anything that has mass and takes up space Matter   -Anything that has mass and takes up space

Atoms   Parts of an Atom Nucleus Electrons Shells -Smallest particle of matter -center of the atom -Neutrons-neutral (0) -Protons-positive (+) -Electrons-negative (-) -They move rapidly around the nucleus -The further from the nucleus it is, the more energy it has

Ions   Charges -Gain or loss of electrons -(+) have fewer electrons -(-)have extra electrons

Elements   Periodic Table  You need to know -a pure substance made of just one kind of atom - Can predict the ability of atoms to react  hydrogen carbon nitrogen oxygen sodium potassium sulfur phosphorus calcium

Isotopes   Radioisotopes -atoms of the same element that differ in the number of neutrons they contain -isotopes with unstable nuclei, their nuclei tend to release particles or radiant energy or both

Compounds   Example -When two or more elements chemically combine to form a new substance -If Na mixes with water it becomes explosive -Cl is a poisonous green gas -When you combine Na and Cl you end up with NaCl – table salt

  Molecular Formula Examples -Shows the proportions of each kind of atom in a compound -It is the proportion of atoms that give compounds their chemical personality H2O (water) = 2 Hydrogen and 1 Oxygen H2O2= 2 Hydrogen and 2 Oxygen

Mixtures   Solution Solvent Solute Example -Molecules of different substances mingling without combining chemically -particles of one substance disperse in another substance to make a uniform mixture -a substance that dissolves -Water is a universal solvent -a substance that gets dissolved Sugar dissolves in water

   Energy    Exergonic (exothermic) Endergonic(endothermic) Activation Energy  -All atoms and molecules in any substance are in constant motion (heat is a form of energy) -Energy is never destroyed or created it only changes form -release of energy Example -burning of wood -feels hot -use of energy -Cellular reactions -feels cold (in non-living things) -energy required to start a chemical reaction

Chemical reactions   Ionic Bond Covalent Bond    Example -process of breaking existing chemical bonds and forming new bonds -when an atom transfers an electron to another atom -Covalent-occurs when 2 or more atoms share an electron -Covalent bonds do not break easily -water H2O, each hydrogen gets it’s electron part of the time and oxygen gets it the other part of the time -Usually there will be a slightly negative end (where the electron spends most of its time) and a slightly positive end to a molecule

Equations   Reactants Products Arrow Symbols -describe what happens in a chemical reaction -do the reacting - are produced during reaction, on right side of the arrow -points in the direction of the products (always) -Subscript-fixed number that tells the number of atoms of an element in one molecule -Coefficients-the correct proportion of substances in the reaction

Acids and Bases   Acids (acidity) Bases (alkalinity) pH scale -pH range of 0-7 -stomach pH2, Vinegar pH3, Urine pH6 -Chemical opposite of an acid -Bases – Ammonia pH12, -Milk of magnesia pH10.5 -pH range of 7-14 -Below 7 is an acid -7 is neutral (water) -Above 7 is a base