Question

1. use the word hydrophobic or hydrophilic to complete the following: a. molecules like to interact with water. b. molecules do not like to interact with water. c. molecules like to interact with hydrophobic molecules. 3. explain why water is called a polar molecule. 4. how does water dissolve sodium chloride (nacl)? 5. draw the phospholipid bilayer of the cell membrane (find a picture in the textbook or online). label the hydrophobic and the hydrophilic parts. knowing that the cells cytoplasm (cytosol) is made up of a lot of water and that the environment outside the cell is very watery, explain why the phospholipid bilayer is oriented this way.

Explanation:

1. a. Hydrophilic molecules like to interact with water as they have polar groups that can form hydrogen - bonds with water. b. Hydrophobic molecules do not like to interact with water as they are non - polar and cannot form hydrogen bonds with water. c. Water is a polar molecule because of the unequal sharing of electrons between oxygen and hydrogen atoms, creating partial positive and negative charges.
2. Water is polar due to the bent molecular shape and the electronegativity difference between oxygen and hydrogen. The oxygen atom is more electronegative, pulling electrons towards itself, resulting in a partial negative charge on oxygen and partial positive charges on hydrogen. This polarity allows water to form hydrogen bonds with other polar substances.
3. Sodium chloride (NaCl) is an ionic compound. When it dissolves in water, the polar water molecules surround the sodium (Na⁺) and chloride (Cl⁻) ions. The partially negative oxygen atoms of water are attracted to the Na⁺ ions, and the partially positive hydrogen atoms of water are attracted to the Cl⁻ ions, breaking the ionic bonds in NaCl and dispersing the ions in the water.
4. In a phospholipid bilayer of the cell membrane, the hydrophilic heads face the watery cytoplasm (cytosol) and the extracellular environment, while the hydrophobic tails face each other in the interior of the bilayer. This arrangement occurs because the hydrophilic heads can interact with water, and the hydrophobic tails avoid water, creating a stable membrane structure.

Answer:

1. a. Hydrophilic molecules like to interact with water.

b. Hydrophobic molecules do not like to interact with water.
c. Water is a polar molecule.

1. Water is polar due to unequal electron - sharing and electronegativity difference.
2. Water's polarity allows it to surround and separate Na⁺ and Cl⁻ ions of NaCl.
3. Hydrophilic heads face water; hydrophobic tails face each other in the bilayer.