EXAM 1 ( Chemical Foundations of Bio; Water and the Environment’s fitness; Carbon and Molecular Diversity; Macromolecules ) The number of protons in an uncharged atom equals the number of electrons Two atoms of the same element must have the same number of protons Isotopes of an element will always differ in atomic mass A covalent bond is likely to be polar if one of the atoms sharing the electrons is much more electronegative Hydrogen bonds occur when partial opposite charges on molecules come close enough to attract each other The number of bonds atoms can form depend on the number of valence electrons An element has 9 protons, 10 neutrons, and 9 electrons. Its atomic number and atomic mass, respectively, are 9 and 19 The chemical characteristics of an element depend mostly on the number of electrons in its outer shell Oxygen (O) is much more electronegative then hydrogen (H). Which of the following statements is correct about H20 each hydrogen atom has a partial positive charge Which of the following statements describes a reversible reaction that has reached chemical equilibrium the rate of the reverse reaction equals the rate of the forward reaction In a group of water molecules, hydrogen bonds form between the oxygen atom in one water molecule and a hydrogen atom in another water molecule When two atoms are equally electronegative, they can interact to form nonpolar covalent bonds Because molecules of water are farther apart in ice than in liquid water ice floats Water is a very versatile solvent because water molecules are polar Hydrophobic molecules are. . repeled by water An acid is a compound that donates hydrogen ions to a solution A substance that minimizes changes in the concentration of H+ and OH- in a solution is a(n) buffer What would be the pH of a solution with a hydroxide ion concentration (OH-) of 10-8M 6 What do the following have in common with reference to water: cohesion, surface tension, specific heat all are properties related to hydrogen bonding A molecule that has all nonpolar covalent bonds would be hydrophobic The carbon atom is tetravalent; this means that a carbon atom can complete its valence shell by forming four covalent bonds Which of these is found in all amino acids Both –COOH and –NH2 Which one of the following molecules has carboxyl functional group R-COOH Which of the following functional groups is associated with a release of energy that cells can harvest to perform many functions phosphate Which two functional groups are part of the monomers of polypeptides carboxyl and amine A chemist wishes to make an organic molecule less acidic, which of the following functional groups should she add to the molecule amino What is the process by which cells link monomers together to form polymers dehydration/condensation synthesis Cellulose is a ….Made of many… polymer, glucose molecules In what polysaccharide form do plants store glucose to be available later as an energy source starch Which one of the following components of a tossed salad
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