Mentioned in email Biology Final Review Polarity Hydrophobic H ion concentration is the basis for pH H ion concentration is also a major concept in cellular respiration and photosynthesis because it is the H concentration differences that provide the proton motive force that drives ATP synthesis Overall process of cellular respiration involving the oxidation of large molecules and electrons are stripped from those molecules to drive ATP production through the electron transport chain and chemiosmosis Oxidation Reduction Exergonic Endergonic Exam 1 Study Guide Chapter 2 The Chemical Context of Life Thoroughly understand the structure of an individual atom The atomic nucleus Made up of protons and neutrons Atomic number How many protons are in the nucleus Atomic mass Number of protons and neutrons Isotopes Two atoms of the same element with different numbers of neutrons in their nuclei The arrangement of electron shells There are multiple shells surrounding the atomic nucleus the third shell has the highest energy level the second shell has the next highest and the first shell has the lowest energy level Valence electrons An electron of an atom located in the outermost shell the valence shell of the atom that can be transferred to or shared with another atom Relative potential energy of electrons The relative potential energy of electrons depends on the position of the electron relative to the nucleus Know the types of bonds that form between atoms and why Covalent bonds A chemical bond that involves the sharing Which types of atoms form covalent bonds with each other of electron pairs between atoms Non metals ones with similar electronegativity such as carbon oxygen nitrogen Polar vs non polar covalent bonds Polar covalent bonds are a type of chemical bond between 2 non metal atoms where a pair of electrons is unequally shared between two atoms and one atom has a stronger pull than the other atom and attracts electrons example water aka H2O Non polar covalent bonds are a type of bond that occurs between 2 non metal atoms when they share a pair of electrons with each other the shared electrons glue two or more atoms together to form a molecule they have the same electronegativity example H H bond is between two atoms has one electron pair sharing form the valence shell of both the atoms For double covalent bonds the pair of electrons sharing form the valence shell of the respective atoms increases by two and three respectively Single vs double covalent bonds A single covalent Ionic bonds The complete transfer of valence electron s between atoms it generates two oppositely charged ions Which types of atoms form covalent bonds with each other Weak interactions Do not involve the exchange or sharing Hydrogen bonds Important weak bond forms when a of electrons Non metals hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom Understand the concept of chemical equilibrium It is reached when the forward and reverse reactions occur at the same rate At equilibrium the relative concentrations of reactants and products do not change Chapter 3 Water and Life Realize the importance of hydrogen bonds between water atoms Water molecules are held together by hydrogen bonds and they are responsible for the characteristics of water Understand how hydrogen bonds are responsible for the following The cohesion of water The hydrogen bonds create a slightly positive side and a slightly negative side that allow the water to stick easily together and break apart Resistance to changes in temperature Water absorbs heat from warmer air and releases stored heat to cooler air and it can absorb or release a large amount of heat with only a slight change in its own temperature due to its high specific heat measure of the total kinetic energy due to molecular motion and temperature measures the intensity of The storage and release of heat energy Heat is a heat due to the average kinetic energy of molecules A calorie is the amount of heat required to raise the temperature of 1 g of water by 1 degree Celsius A joule is also a unit energy where 1 J 0 239 cal or 1 cal 4 184 J The specific heat of a substance is the amount of heat that must be absorbed or lost for 1 g of that substance to change the temperature by 1 degree Celsius The specific heat of water is 1 cal g degree Celsius Water resists changing its temperature because of its high specific heat Hydrogen bonds break when heat is absorbed and is released when hydrogen bonds form The high specific heat of water minimizes temperature fluctuations to within limits that permit life Heat of vaporization is the heat a liquid must absorb for 1 g to be converted to gas As a liquid evaporates its remaining surface cools a process called evaporative cooling in water The ability is based on the presences of polarity in the molecules In inability of non polar hydrophobic molecules to dissolve in water This inability is because of the relatively non polar bonds The ability of polarized hydrophilic molecules to dissolve Understand the concept of Molarity and how it relates to molecular mass Molecular mass is the sum of all masses of all atoms in a molecule The number of molecules are usually measured in moles where 1 mole mol 6 02 x 10 23 molecules Molarity is the number of moles of solute per liter of solution Know the chemical basis for acids and bases A hydrogen atom in a hydrogen bond between two water molecules can shift from one to the other leaving its electron behind so it is transferred as a proton or hydrogen ion H The molecule with the extra proton is now a hydronium ion H3O though it is often represented as H The molecule that lost the proton is now a hydroxide ion OH An acid is any substance that increases the H concentration of a solution A base is any substance that reduces the H concentration of a solution pH stands for the Potential of Hydrogen which is a measurement of the relative amount of H ions in a solution Focus on the concentration of H and OH ions and the relationship between the two In pure water at 25 degrees Celsius the concentration of H and the concentration of OH are both 1 0 x 10 7 M This means that the concentrations are equal and is described as a neutral solution In most cases when H increases OH decreases and vice versa H OH 10 14 What molecules can change either the H or OH concentration of a solution Acids dissociate into H and lower pH bases dissociate into OH and raise pH and
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