Due Sept. 24: Chemistry Assignment

Please answer the following questions and email your responses to bio1homework@lesleybio.net with the subject line Chemistry Assignment by 5pm Sept. 24th. Or turn in your responses on paper during class on Sept. 24th. If you have any questions about the assignment, let us know in the comments section of this blog post.

1. A covalent bond is
(a) a single shared electron (b) the attraction between two oppositely charged ions (c) a pair of shared electrons (d) nondirectional

2. How many electrons are in the outer shell of the following atoms?
bromine (Br) ___ neon (Ne) ___ potassium (K) ___

3. How many electrons do the following atoms need to complete their outer shells?
phosphorus (P) ___ hydrogen (H) ___ Argon (Ar) ___

4. Give an example of an ionic compound that we have not discussed in class. How many electrons are lost and gained by the atoms that make up the compound?

Select the characteristic of water responsible for each phenomenon.

5. Water soaking into paper
(a) adhesion (b) cohesion (c) polar solvent

6. Water dissolving sugar
(a) adhesion (b) cohesion (c) polar solvent

7. You have to shake vinaigrette salad dressing to mix the oil with the water, but the vinegar in the dressing stays mixed with the water because it is
(a) hydrophobic (b) hydrophilic (c) covalently bonded with water molecules (d) ionically bonded with water molecules

8. Lemon juice has a pH value of 2. How many hydrogen ions does lemon juice have relative to pure water?
(a) 5 times more (b) 10,000 times more (c) 5 times fewer (d) 10,000 times fewer

9. Describe the difference between adhesion and cohesion.

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One thought on “Due Sept. 24: Chemistry Assignment”

  1. Here are the answers…

    1. A covalent bond is
    (a) a single shared electron

    2. How many electrons are in the outer shell of the following atoms?
    bromine (Br) 7; neon (Ne) 8; potassium (K) 1

    3. How many electrons do the following atoms need to complete their outer shells?
    phosphorus (P) 3; hydrogen (H) 1; Argon (Ar) 8

    4. Give an example of an ionic compound that we have not discussed in class. How many electrons are lost and gained by the atoms that make up the compound?

    MgBr2 (magnesium loses two electrons, each bromine gains one); NaF

    Select the characteristic of water responsible for each phenomenon.

    5. Water soaking into paper
    (a) adhesion

    6. Water dissolving sugar
    (c) polar solvent

    7. You have to shake vinaigrette salad dressing to mix the oil with the water, but the vinegar in the dressing stays mixed with the water because it is
    (b) hydrophilic

    8. Lemon juice has a pH value of 2. How many hydrogen ions does lemon juice have relative to pure water?
    none of the options given; 100,000 times more

    9. Describe the difference between adhesion and cohesion.
    cohesion is water molecules sticking together; adhesion is water sticking to other things

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