BSC2010 EXAM 1 DENNIS Chapter 1 6 in BOOK Lecture NOTES 1 7 1 10 12 Hydrocarbons stronger bonds gasoline Matter consists of pure elements and combinations of elements called compounds o organisms are composed of matter o matter anything takes space and has mass Elements and compounds matter is made up of elements element is a substance that cannot be further broken down by chemical reactions compound substance consisting of 2 or more elements in a fixed ratio Periodic Table Rows top to bottom are layers of electrons First Shell Second shell Third Shell Outermost shell can contain 8 electrons Outermost shell goes from left to right starting with 1 then 2 3 4 all the way to 8 Essential elements in life Figure 2 1 About 25 elements are essential C H N O Make up 96 of living matter Most of remaining 4 is Calcium Phosphorus potassium sulfur Trace Elements are required in minute quantities Elements properties depend on structure of atoms Sodium explosive metal Chlorine dangerous Chemical Sodium Chloride Emergent property New Property formed by compounds Each element consists of unique atoms An atom is smallest unit of matter that retains the property of an element Atoms are composed of subatomic particles ON TEST Particle Neutron Charge Neutral 0 Mass 1 Dalton Location Atomic Nucleus Proton Electron Positive Negative 1 Dalton No Mass 0 Atomic Nucleus Electron Cloud Isotopes All Atoms of an element are defined by the number of protons Isotopes are two atoms that differ in the number of neutrons Unstable giving off energy Energy level of electrons Energy is the capacity to cause change Potential energy is energy due to location or structure Electrons e of an atom differ in their energy Lowest Shell is located closest to Atomic Nucleus Lowest Shell has lowest energy Highest Shell has Highest Energy Glow in the dark Light gives energy to bump up electrons and as they fall back down a faint light is given off Electron distribution and chemical properties Chemical behavior of atom is determined by the distribution of electrons in electron shells The Period Table shows the electron distribution for each element ON TEST See a periodic Table Day two slides asking to provide number of electrons Atomic number or mass Given the name of element Once a lower shell is filled it is no longer needed to understand electron Valence Electrons are outermost shell Outermost Shell is Valence Shell The Chemical Behavior of Atom is determined mostly by valence electrons Elements with full valence shells are full at maximum capacity 8 Chemically inert Do not react Electronegativity is the propensity of an element or the atom of an element to pull electrons From Bottom left Giving to Top Right Taking Electronegativity Increases WHAT IS THE MOST ELECTRONEGATIVE ATOM THAT MAKES UP 96 OF LIVING MATTER OXYGEN Not Giving or taking CARBON Simplest smallest perfect sharer of electrons Carbon is backbone of life Hydrogen Has one electron Can hold up to two Would add one Equally Shared would bring together two hydrogen to make stable compound H H Stable Covalent Bond Carbon Has four Would need four total of 8 covalent bond with perfect sharing Oxygen More electronegative Hydrogen are shared Lowercase delta on drawing used to show partial charge bonds are easier to break Polar covalent bond unequal sharing of electrons Non polar covalent bond are equal sharing of bonds Chlorine So electronegative that it strips hydrogen of its one electron 7 protons and 7 neutrons Covalent bonds Polar and non polar Because you know the behavior thats represented the shells valence electrons and number to fill in outer shel in addition to electronegativity you can pair up any atoms of any elements you can understand if bonds are shared perfectly or non perfectly shared unequally you define them as partially negative or positive Pair up any of the atoms of any elements The pairing is with an atom that is so electronegative it strips away the electron of another element An ionic bond Hydrogen Bonds found in anything Water Hydrogen bonds found in water are ultimately responsible for life on earth Ice forming in lattice is less dense so it floats if it sank it would build and build The ends and sides of water make it so that the water arranges itself in solid and liquid form in predictable matters Hydrogen bonds are weak interactions Many weak interactions create an incredibly strong interaction 1 15 13 Hydrogen Bonding Water partial negative and partial positive charge oxygen is a taker of electrons more negative Water appears to be unique to earth Covers 3 4 of the earth s surface Constitutes 60 70 of the weight of all life regenerates and is redistributed through the water cycle only molecule that exists naturally on earth in all three states Gas solid liquid absolutely essential to LIFE MUST BE ABLE TO DRAW WATER AND DIPULL MOMENT Concepts Hydrogen Bonding Emergent Properties Acid Base chemistry H H O Solid Form Ice Organized Hydrogen Bonds stable Crystal lattice Ice Hexagonal Lattice More spacious than the liquid form Liquid Form Fragile Disorganized Hydrogen bonds Last only few trillionths of a second constantly broken and reformed Gas Form single molecules liberated by edition of energy Emergent Properties of WATER make H2O ideal for life on earth Adhesion cohesion surface tension ability to moderate temperature evaporative cooling expansion upon freeing universal solvent Adhesion Cohesion Surface Tension Cohesion Phenomenon of Hydrogen Bonds holding water together Surface Tension Measure of how hard to break surface of liquid Adhesion the phenomenon of Hydrogen Bonds of water holding that water to something else Trees As one molecule is lost due to the cohesion of water another is brought up Ability to Moderate Temperature Water absorbs heat from warmer air and releases stored heat to cooler air can absorb a huge amount of heat energy with a slight change in its own temperature EX Shining two heat lamps one on water and one on steel water would be cooler Water has a high specific heat Specific Heat the amount of heat that must be absorbed or lost for 1 gram of that substance to change its temperature by 1 degree celcius 1 ml of water weighs 1 gram 1 calorie per gram per degree celcius 1cal g c Waters high specific heat can be traced to hydrogen bonding Heat is absorbed when hydrogen bonds break Heat is released when Hydrogen bonds form Evaporative Cooling Evaporation is the transformation of liquid to a gas Heat of Vaporization The
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