BIOL 1441 1st Edition Exam 1 Study Guide Lectures 1 10 Lecture 1 January 15 Structure function Atom smallest unit of matter that still retains the properties of an element o Electrons o Protons o Neutrons neutral o ALL HAVE NEUTRAL CHARGE UNLESS OTHERWISE INDICATED o of protons of electrons Matter made up of elements o Protons neutrons make up nucleus Anything that takes up space has mass Element cant be broken down into other substances by chemical reactions o Trace element required in minute quanitities Iron iodine Goiter iodine deficiency o Categorized by the of atoms o Carbon oxygen hydrogen nitrogen Make up about 96 of all living matter Compound substance consisting of 2 or more DIFFERENT elements combined in a fixed ratio Atomic mass weight of nucleus neutrons protons o Electrons weigh almost nothing o Dalton atomic mass unit 1 proton or 1 neutron 1 dalton Atomic number of protons o All atoms of a particular element have the SAME number of protons Isotopes same elements but different of neutrons mass will change o Atomic number stays the same number of protons didn t change o Atomic mass changes o Radioactive isotopes unstable Start spontaneously decaying Gives off particles energy Give off proton element change Energy When atoms collide only the ELECTRONS interact Energy capacity to cause change o Kinetic energy energy of movement o Potential energy energy matter possesses due to location or structure low energy stable electrons have potential energy Electrons have greater potential energy since the electrons are very attracted to the positively charged nucleus so it takes more energy to keep them farther away from the nucleus in the outer valence shell The closer the electron is to the nucleus the lower the potential energy MATTER MOVES TO THE LOWEST POSSIBLE STATE OF POTENTIAL ENERGY Energy level how much potential energy electrons possess o Correlates to the average distance from nucleus Electron shells energy levels o Electrons can move through them o Absorbing energy moving farther away from nucleus o Losing energy moving closer to the nucleus Chemical properties Chemical behavior is determined by ELECTRON CONFIGURATION Chemical behavior depends on the of electrons in the outermost shell VALENT SHELL Valence electrons electrons in the outermost shell Valence shells o 1st shell can hold 2 electrons o 2nd shell can hold up to 8 electrons o 3rd shell can hold up to 8 electrons o Full valence shell stable unreactive inert o Incomplete valence shell unstable reactive o Shells are not actually real just a space Orbital pathways that the electrons move through o Each orbital can hold 2 electrons Shell 1 1s 1st orbital Shell 2 2s 1st orbital 3p 3rd orbital fills up after 2s Lecture 2 January 17 chemical bonds Unpaired electrons reactive Atoms combine to fill their valence shells o Covalent strongest o Ionic 2nd strongest o Hydrogen weakest A covalent bond is a very strong chemical bond that occurs when one or more pairs of electrons are shared between two atoms o Polar covalent bond is a covalent bond where the electrons are not shared equally so there is a charge a water molecule o Nonpolar covalent bond is a covalent bond where electrons are shared equally so there is no charge 2 atoms of the same element o Molecule 2 or more atoms held together by a covalent bond single covalent bond hydrogen molecule shares 1 electron H H Double covalent bond oxygen molecule shares 2 electrons O O Valence the bonding capacity o The number of electrons it takes to fill the valence shell Electronegativity the attraction of an atom for the electrons in a covalent bond CANT CHANGE o The more electronegative an atom the more strongly it pulls shared electrons to itself HIGH ELECTRONEGATIVITY Oxygen Nitrogen LOW ELECTRONEGATIVITY Hydrogen Carbon NON POLAR pairs of the same element bonded O O N N C C H H C H Water is a polar molecule o Delta partial charge POLAR O C O H N C N H What is an ionic bond Ionic bond is also a strong bond that forms between two atoms of different charges one negative and one positive o Ex Sodium chloride o Ion a charged atom molecule that has lost or gained an electron Lose electron positive charge CATION Gain electron negative charge ANION TRANSFERRING THE ELECTRON IS NOT THE FORMATION OF AN IONIC BOND o Transfer of electron creates an ION Ionic compounds salts o In nature found as crystals 3D lattice structure o Only has a RATIO of elements NaCl 1 1 MgCl2 1 2 What is a hydrogen bond Hydrogen bond relatively weak bonds between polar molecules o Hydrogen atoms covalently bonded to one electronegative atom in another polar covalent bond o Easy to pull apart replicate Chemical reactions Chemical equilibrium when the rate of forming and breaking forward reverse chemical bonds in a reaction is the same but not the quantities of the reactants and products Rate of reaction concentration of reactants o More reactants for frequent collisions so more reaction more bonds formed Lecture 3 January 22 water Hydrogen bonding is responsible for water properties Water is the only substance that naturally exists in all 3 states liquid solid gas Water properties o Cohesion o Moderation of temperature o Expansion upon freezing o Universal solvent Cohesion holds substances together o H2O molecules are attracted to each other b c of Hbonds o Contributes to the transport of water and dissolved nutrients against gravity in plants Water evaporates from leaves Upward pull is transported through all cells from roots o Adhesion clinging of one substance to another Water adheres to walls of the cells o Surface tension measure of how difficult it is to stretch break the surface of a liquid Moderation of temperature o Water heat band stores heat Can lose and gain lots of heat and not change much in temp o Heat TOTAL amount of kinetic energy due to the molecular motion in a body of matter Is a form of energy depends on the volume of the matter o Temperature AVERAGE of kinetic energy Average speed of molecules increase temperature increases o Heat and temp are related but NOT the same Ex Humans have a higher temperature than the ocean but the ocean has more heat more volume o ENERGY WILL FLOW FROM HIGH TO LOW CONCENTRATION Heat will always pass to the cooler object until the two are the same temp o Water freezes 0 C o Water boils 100 C o Human body 37 C o Room temp 20 25 C o Refrigerator 4 C Measure of heat Calorie amount of heat it takes to raise the temperature of 1 gram of water by 1 C o