i ii iii i ii iii i i i ii i BSC 2010 FINAL EXAM STUDY GUIDE I Unit 1 A Basic Chemistry 1 Protons Neutrons Electrons a Atom b Subatomic Particles Neutrons no charge 1 In the nucleus Protons charge 1 In the nucleus Electrons charge 1 Form a cloud around the nucleus the smallest unit of matter that still retains the properties of an element c Atomic number d Mass number e Isotopes the of protons in nucleus the sum of protons neutrons in nucleus have the same number of protons but may differ in number of neutrons decay spontaneously giving off particles and energy Isotope Radioactive Isotopes Applications of radioactive isotopes 1 Dating fossils 2 Tracing atoms through metabolic processes 3 Diagnosing medical disorders 2 Periodic Table e in shells valence a Energy b Potential energy the capacity to cause change energy that matter has because of its location or structure Electrons of an atom differ in their potential energy c Electron shell energy level an electron s state of potential energy Chemical behavior of an atom is determined by the distribution of electrons in electron shells d Valence electrons electrons in the outermost shell Chemical behavior of an atom is mostly determined by the valence e Elements with full valence shell are chemically inert e Orbital a 3D space where an electron is found 90 of the time Each electron shell consists of a specific number of ortbitals 3 Electronegativity a The more electronegative an atom the more strongly it pulls shared electrons toward an atom s attraction for the electrons in a covalent bond electrons are shared equally electrons are NOT shared equally b Nonpolar c Polar d Unequal sharing of electrons causes a partial positive or negative charge for each atom itself or molecule 4 Bonds a Atoms with incomplete valence shells can share or transfer valence electrons with b Chemical bonds c Covalent Bonds certain other atoms i ii Molecule when atoms stay close together the sharing of a pair of valence electrons by two atoms The shared electrons count as part of each atom s valence shell consists of 2 or more atoms held together by covalent bonds BSC 2010 FINAL EXAM STUDY GUIDE sharing of one pair of valence electrons sharing of two pairs of valence electrons combination of two or more different elements the atom s valence atoms share the electron equally one atom is more electronegative and the atoms do not Single covalent bond Double covalent bond Structural Formula H H iii iv v vi Molecular Formula H2 vii viii ix x Compound Bonding capacity Nonpolar covalent bond Polar covalent bond share the electron equally d Ionic bonds i ii iii attraction between an anion and a cation Atoms strip electrons from their bonding partners After the transfer both atoms have charges Ion 1 Cation 2 Anion Ionic compounds Salts are often found in nature as crystals a charged atom a positively charged ion a negatively charged ion iv v compounds formed by ionic bonds salt e Weak Chemical Bonds i Most of the strongest bonds are covalent bonds that form a cell s molecules ii Ionic bonds and Hydrogen bonds are weak chemical bonds 1 Hydrogen bonds formed when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom a Electronegative partners are usually Oxygen or Nitrogen together as a result of hot spots of positive or negative charge a If electrons are distributed asymmetrically they can result in hot spots of positive or negative charge interactions between molecules that are close 2 Van der Waals Interactions 5 Molecular Shape Function a Molecules shape is important for its function b Shape is determined by positions of the valence orbitals c In covalent bond the s and p orbitals may hybridize creating specific molecular shapes 6 Chemical Reactions MAKE and BREAK chemical bonds the starting molecules of a chemical rxn the final molecule of a chemical rxn a Reactants b Products c Photosynthesis is important chemical rxn d Sunlight powers conversion of CO2 and H2O into Glucose and Oxygen i 6CO2 6H2O C6H12O6 6O2 e Some chemical rxns go to completion all reactants are converted to products f All chemical rxns are REVERSIBLE products of the forward reaction become reactants for the reverse reaction g Chemical equilibrium reached when the forward and reverse reaction rates are equal BSC 2010 FINAL EXAM STUDY GUIDE 7 8 B Water Carbon 1 Water a Structure i ii i ii iii iv One O is covalently bonded to two H Angle is 105 b Polarity O is electronegative Electrons of H spend more time closer to the O O region gives a slight charge H region has slight charge i c H Bonding Liquid 1 Fragile disorganized hydrogen bonds 2 Constantly reforming ii iii i ii iii iv BSC 2010 FINAL EXAM STUDY GUIDE Solid 1 Organized hydrogen bonds making ice less dense 2 Crystal is more spacious than disorganized liquid Gas 1 Single molecules liberated by addition of energy d Emergent Properties Cohesion Adhesion and Surface tension 1 Cohesion 2 Adhesion of water against gravity in plants plant cell walls 3 Surface tension Ability to Moderate Temperature 1 Heat and Temperature hydrogen bonds hold water molecules together helps the transport attraction between different substances i e between water and measure of how hard it is to break the surface of a liquid a Water absorbs heat from warmer air and releases stored heat to cooler air b Water can absorb or release a large amount of heat with a slight change in c the amount of heat required to raise the temperature of 1g of its own temperature calorie water by 1 C 2 Specific heat amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1 C a Water 1cal g C b Heat is absorbed when hydrogen bonds break c Heat is released when hydrogen bonds form Evaporative Cooling 1 Evaporation 2 Heat of vaporization 3 Evaporative cooling transformation of a substance from liquid to gas a Helps stabilize temperatures in organisms and bodies of water heat a liquid must absorb for 1 g to be converted to gas as a liquid evaporates the remaining surface cools 4 Water reaches greatest density at 4C Universal Solvent 1 Definitions a Solution b Hydrogen shell solvent solute 1 Water is versatile solvent due to its polarity allowing it to form hydrogen bonds easily 2 When ionic compound is dissolved in water each ion is surrounded by hydration shell sphere of water molecules 3 Water can dissolve compounds made of nonionic polar molecules 4 Large polar molecules can dissolve in
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