Exam 1 Session 1

Question 1

Water and Polarity

A) the tendency of an atom to attract electrons to itself in a chemical bond is called __________.

B) in a __________ bond such as the O-H in water, oxygen is more electronegative than hydrogen. therefore the bonding electrons are closer to ____. This difference between the electronegativity gives rise to a partial positive and a partial negative charge.

1. Polarity is a permanent resonance of unshared electrons on one side of the molecule creating a permanent dipole.

C) in a _____ bond such as C-H the electronegativity difference is quite small and the sharing of electrons in the bonds is close to equal.

Answer 1

A) electronegativity

B) Polar, Oxygen

C) nonpolar

Question 2

Hydrogen Bonding

A) a hydrogen bond is an example of a non covalent interaction.

B) in a hydrogen bond a ___ atom is interspersed between two ____ atoms usually O and N. it is covalently bound to one of these.

Answer 2

B) H, electronegative

Question 3

Dipole-Dipole Interactions

A) Bonds with positive and negative ends are called ___.

B) Water is dipolar and forms solutions with other polar molecules (like dissolves like) to form a homogenous mixture.

C) 2nd law of thermodynamics: processes will occur spontaneously in ways that maximize the randomness of the universe.

Answer 3

A) dipoles

Question 4

Forces Between Molecules

A) Four major types of forces between molecules

B)

1. what is the general bond strength of all covalent bonds?
2. what is the general bond strength of the three strongest noncovalent forces?
3. What is the general bond strength of the weakest non covalent force?

C) Name the four types of noncovalent forces

D) name the non-electrical interactions

Answer 4

A) Covalent bond, noncovalent forces, hydrophobic interactions, steric hindrance

B) 100, 10, 0.1

C) Hydrogen bond, ionic interaction, dipole-dipole, van der waals forces

D) hydrophobic interactions, Steric hindrance

Question 5

Hydrophobic Interactions

A) ionic and polar substances are referred to as ____ substances.

B) the interactions between ___ molecules are called hydrophobic interactions.

C) _____; a single molecule having both polar and nonpolar portions.

1. when in water they form ___ in which the polar groups face the outside and the nonpolar groups face the inside.

Answer 5

A) Hydrophilic

B) Nonpolar

C) Amphipathic, Micelles

Question 6

Water vs Oil

1) Methyl groups are ___ and therfore do not bond to water.
2) water molecules will rearrange their H bonds to surround methyl groups which introduces order to the system.
3) The smaller the interface the (less) order is introduced to the system therefore the system will equilibrate to minimize the surface area interface.
4) The best way to do this is for the methyl groups to interact (form a blob) so that the surface area to voume ratio is (minimized).
5) this set of events is (spontaneous)
6) ____ are structures that are formed when water and oil come together.

A) They orient ___ molecules together

B) they conform to the ___ law of thermodynamics by increasing ___ randomness and allowing for more H bonding to the water molecules.

Answer 6

1) hydrophobic
6) clathrate

A) nonpolar

B) 2nd, entropy

Question 7

Acids Bases and pH

A) a ___ is a molecule that acts as a proton donor. a ___ is a proton acceptor.

B) ____ is the acid dissociation constant.

1) the greater the Ka the (stronger) the acid.
2) an acid that is 75% dissociated at equilibrium is (stronger) than an acid that is 15% dissociated at equilibrium.

Answer 7

A) acid, base

B) Ka