Structure of the Atom B. Suspension : mixture where particles are - PDF document

2/18/2013 Everything around us is made up of matter . CHEMISTRY OF LIFE Why is chemistry important? Chemistry is related to Biology because all the Matter: anything that has mass and processes that go on in our world and in your body volume are a result of chemical reactions. - photosynthesis Mass: amount of matter in an object - digestion Volume: amount of space and object - metabolism takes up Biochemistry : chemistry of living organisms Weight: force of gravity on mass Classification of Matter States of matter 1. Solid: definite shape and volume 2. Liquid: indefinite shape, definite volume 3. Gas: indefinite shape and volume Classification of matter B. Compound : two or more elements chemically combined in a definite proportion I. Pure substances : a substance that is identical throughout Ex: H 2 O, H 2 O 2 A. Element : composed on only one type of atom CO 2 , CO Ex: Na, Pb, Cl, etc ……. O 2 , O 3 - 109 elements - 90 natural ** cpds have different properties than original - 19 synthetically made in lab, basically radioactive elements that make them - most solid - represented by symbols (from Latin) Ex: NaCl sodium: metal, poison Ex: lead Pb plumbus Sodium Na natrium Chlorine: gas, poison Iron Fe ferrium 1

2/18/2013 Two types Mixtures II. Mixture : two or more substances (element or compound) A. Solution : mixture where substances are equally distributed mixed but not chemically combined and appear as one substance Components of a solution - original substances keep their identities and can be separated out by physical means Solute : substance being dissolved Ex: salt water – boil off water and collect salt Solvent : substance doing dissolving ex: ice tea mix in water ex: 0.85% NaCl in plasma (water component of blood) Ex of mixtures: salad dressing rocks, sand, water, blood, Aqueous solution : water is UNIVERSAL SOLVENT earth’s atmosphere (O, N, CO 2 , Ar, etc) when two same states of matter: solvent is substance in larger amount Structure of the Atom B. Suspension : mixture where particles are too small to Atom : basic unit of matter, pure substance settle and stay suspended due to movement Subatomic structure of water molecules Protons – positive, inside nucleus 1. Ex: milk 2. Neutrons - neutral, inside nucleus 3. Electrons - negative, outside nucleus equals the number of protons Example of solution and suspension: ( size of nucleus compared to whole atom blood: salt in water - solution is like pea in giants stadium ) blood: cells in saline - suspension Atomic number = protons Protons = Electrons Atomic mass = protons + neutrons Uses of Isotopes Isotopes : different form of the same element due to different number of neutrons - Study age of fossils and rocks C 14 • most radioactive (elements with unstable nuclei which break down and emit particles) - Radiation therapy: cobalt 60, cancer carbon 14, brain tumors Ex: C 12 , C 13 , C 14 6 protons 6 protons 6 protons 6 neutrons 7 neutrons 8 neutrons - Medical tests: cobalt 60 H 1 H 2 H 3 protium deuterium tritium Thallium, stress tests 1 proton 1 proton 1 proton Iron 59, blood circulation 0 neutrons 1 neutron 2 neutrons Iodine, thyroid tests 2

2/18/2013 Bonding Bonding Basics Chemical bond : process if joining atoms in a compound • Electrons are subatomic particles involved in bond • Goal of bond: to complete outer shell and become stable • To form a compound electrons: - gain - lose - share Types of Bonds Bonding Basics 1. Ionic : • Atoms try to fill valence transfer of electron between shell (orbital) to become metal and non metal stable - metal gives electrons to • H and He: need 2 valence non metal electrons - i ons (charged atoms) • All other atoms: need 8 formed valence electrons Ex: NaCl, • Metals lose electrons MgBr 2 • Non metals gain electrons - strong magnetic attraction keeps compound together Types of Bonds Types of Bonds 2. Covalent : 3. Hydrogen : two non metals share electrons weak chemical attraction between polar molecules - called molecules ex: H2O, CO2 - interparticular forces keep atoms together 3

2/18/2013 WATER AND SOLUTIONS WHENEVER BOND IS FORMED A CHEMICAL CHANGE TAKES PLACE • universal solvent in organisms Chemical reaction (change): • one of few liquid compounds found naturally on earth, most solid process in which a chemical change occurs due to bonding • expands in solid form Ex: decaying of apples digestion of food • covers > 75% of earth burning of coal decomposition of plants • most abundant compound in living organisms rusting of iron (human body ~ 70%) EVERYTHING THAT OCCURS IN LIVING • most important compound in organisms ORGANISMS IS A RESULT OF CHEMICAL - cells surrounded by it - filled with it REACTIONS. - cellular events occur in it) - carries or dissolves other substances Properties of Water 2. Cohesion/Adhesion 1. Polar molecule (polarity) • Cohesion : attraction of same substances of same kind Will carry or dissolve other (water to water) substances in it which are vital for life. • Adhesion : attraction of water to other materials - Hydrophilic : substances that dissolve rapidly in water - oxygen end: negative charge *Generally polar molecules - hydrogen end: positive charge. or ions (unlike charges highly attracted to each other) The hydrogens of one water molecule are attracted to the oxygen from other water - Hydrophobic : substances that molecules. This attractive force is what gives are insoluble in water water its cohesive and adhesive properties. *Generally non-polar molecules (water molecules are more attracted to each other than the non polar molecules) 3. Surface Tension : cohesion of water molecules at the 4. Capillary Action surface of a body of water adhesion of water molecules to other - Each molecule in the water drop is attracted to substances which allow it the other water molecules in the drop. to be drawn up the surface of the other subst. - This causes the water to pull itself into a shape with the smallest amount of surface area, a Ex: meniscus bead (sphere). plants pull water - All the water molecules on the surface of the into themselves bead are creating surface tension. (like a large group of people tightly holding hands) water “climbing” up a straw 4

2/18/2013 IONS AND LIVING CELLS 5. Stores heat efficiently Salt is a very important polar molecule. - When mixed with water, the ionic bonds are broken and the Na and Cl ions separate ( dissociation) - absorbs a lot of energy before it will raise its - The charged ends of each ion are attracted to the polar ends of temp. water - retains its heat longer than many other substances - This is very important because ions such as Na, Cl, K, and Ca are involved in many reactions inside the cell - this property keeps temperature fluctuations to a minimum in order support life on land and in water Ionization pH: number of H ions in a solution Process of water (non-ionic) being converted into ions Acid : any compound that releases H ions into water - H 3 O + (hydronium ion is formed) Result: ex: hydrochloric acid in water Separate H+ and OH- ions HCl  H+ + Cl- H+ combines with water to make H3O+ ion **** Most reactive ion due to no electrons- attacks bonds in many molecules Base : compound that releases OH- ions into water Ex: NaOH  Na+ + OH- • Neutralization reaction : production of The pH scale H 2 O from mixture of strong acid and base Acid : below ph 7 (more H ions) neutral H = OH Base : above pH 7 (more OH ions) acidic H > OH IMPORTANCE OF PH: basic, alkaline H < OH • most reactions in organisms can only occur with enzymes Buffer • enzymes very pH specific solution which resists changes in pH when small quantities of an acid or an alkali are added to it ***failed kidney function is most often reason for inability to maintain normal blood pH • Important in maintaining pH in organisms 5