BI0L 1110

Indicate whether each of the following statements about covalent bonds is true or false.

1. A water molecule is held together by two single polar covalent bonds. true 2. Because oxygen has a greater electronegativity than hydrogen, water molecules are polar with two partial negative charges near the oxygen atom and one partial positive charge near each hydrogen atom. true 3. Atoms differ in their affinity for neutrons, a property called electronegativity. false 4. In general, electronegativity increases from left to right across each row of the periodic table and also increases down each column. false 5. In a nonpolar covalent bond there is an equal sharing of electrons between two atoms while polar covalent bonds involve an unequal sharing of electrons. true 6. A single molecule of oxygen (O2) is held together by two double nonpolar covalent bonds. false 7. A covalent bond is formed when two atoms share one or more pairs of electrons. true 8. Polar molecules are electrically neutral but the distribution of charge within the molecule is not uniform. true 9. Although C and H differ slightly in electronegativity, this small difference is negligible, and C-H bonds are considered polar. false 10. Of the 4 most common elements found in living organisms, nitrogen has the highest electronegativity and, therefore, the greatest affinity for electrons. false 11. A slightly positive hydrogen atom on one water molecule can attract the slightly negative oxygen atom on a different water molecule, leading to the formation of a hydrogen bond. true

Given the electronegativity of each of the following atoms, place the bonds in order from most polar to least polar. O = 3.5, N = 3.0, C = 2.5, H = 2.1.

Correct: 3 C-N Correct: 4 C-H Correct: 2 C-O Correct: 1 O-H Correct: 5 C-C

How is the bond in F2 different from the bond in KCl?

F2 is covalent and KCl is ionic

Given the atomic numbers of the following atoms, order the atoms by the number of covalent bonds they could form, from least to most. O = 8, N = 7, C = 6, H = 1.

H=1, C=4, N=3, 0=2

You identify an enzyme involved in a cellular reaction. How does the enzyme affect the reaction equilibrium between reactants and products and the time needed to reach equilibrium?

The reaction equilibrium is unaffected, but it shortens the time needed to reach equilibrium.