Link to Chemistry for Biology Students: Student Learning Guide

1. To understand biology, you need to understand (some) chemistry

Biology (the science of life) is based on chemistry (the study of matter).

rotating DNA-375
DNA, the molecule of heredity. Click to see a larger, 3-D, rotating view (By brian0918™  via Wikimedia Commons)
  • EXAMPLE 1: How did you inherit your biological traits (such as height, skin color, physical appearance, etc.) from your parents? Heredity is based on DNA, the molecule that tells cells what to do and directs how bodies develop. DNA’s structure, along with its ability to direct its own replication and to control cells and patterns of development, is all chemistry.
  • EXAMPLE 2: When you get ill, how do you fight off infections? Your immune system works through the action of huge molecules called  antibodies. Antibodies have a specific shape that lets them destroy organisms that invade your body. The shape is determined by the internal chemistry of the antibody.  

You don’t need to know a lot of chemistry to understand biology. Most of what you need is taught in an 8th grade science class. So what follows the next tutorials is a brief review: the chemistry that you’ll need in your biology course.

2. What you’ll learn in these chemistry tutorials

These tutorials cover

  1. The structure of atoms
  2. The chemical symbols of the most common atoms
  3. How to read a chemical formula
  4. Key chemistry terms
    1. element
    2. compound
    3. molecule
    4. ions
  5. The “Octet Rule” for electron configuration
  6. Ionic Bonds
  7. Covalent Bonds
  8. Structural Formulas

3. A Basic Chemistry Pretest

[qwiz repeat_incorrect=”false”; style = “border: 3px solid black; ” qrecord_id=”sciencemusicvideosMeister1961-Basic Chemistry Prequiz (M3)”]

[h] PRETEST: Basic Chemistry
[i]Before starting, let’s assess what you already know. Don’t worry if you don’t know a lot—it’s just a pretest. Just taking this pretest will improve your learning, so don’t skip it.

[!]QUESTION 1 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”atomic structure and drawing atoms”]The building block of matter is the

[c] nucleus

[c*] atom

[c] proton

[c] electron

[f] No. The nucleus is the central part of the building block of matter. What would you call the unit that makes up the nucleus plus the electrons?

[f] Correct. Atoms are the building blocks of matter.

[f] No. Protons are found in the nucleus. What would you call the unit that makes up the nucleus plus the electrons?

[f] No. Electrons orbit outside the nucleus. What would you call the unit that makes up the nucleus plus the electrons?

 

[!]QUESTION 2 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”atomic structure and drawing atoms”]Electrons are found in

[c] the nucleus

[c*] energy levels

[f] No. The nucleus is the central part of the atom, where protons and neutrons are found.

[f] Correct. Electrons are found in energy levels (also called shells)

[!]QUESTION 3 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”elements, compounds, molecules, formulas”]An element is composed of

[c*] Only one type of atom

[c] At least two types of atoms

[c] Only atoms that have lost their electrons

[f] Yes. An element is a substance that is composed of only one type of atom.

[f] No. Substances composed of two or more types of atoms are compounds (and we’ll learn more about them later.

[f] No. While an atom might temporarily lose its electrons (more about that later), there are no substances that are composed of atoms that have lost their electrons.

[!]QUESTION 4 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”elements, compounds, molecules, formulas”]Which of the following could NOT be the chemical symbol for an element

[c]Fe

[c*]Heg

[c]I

[c]Mn

[f] No. Chemical symbols consist of one or two letters. The first (or only) letter is capitalized. The second letter is lower case. “Fe” is a perfectly legitimate symbol…the symbol for the letter Iron.

[f] Yes: “Heg” could NOT be a chemical symbol for an element. Chemical symbols consist of one or two letters. The first (or only) letter is capitalized. The second letter is lower case. With three letters, “Heg” is not a legitimate chemical symbol. 

[f] No. Chemical symbols consist of one or two letters. The first (or only) letter is capitalized. The second letter is lower case. “I” is a perfectly legitimate symbol…the symbol for the element Iodine.

[f] No. Chemical symbols consist of one or two letters. The first (or only) letter is capitalized. The second letter is lower case. “Mn” is a perfectly legitimate symbol…the symbol for the element Manganese

[!]QUESTION 5 ++++++++++++++++++++++++++++++++++++++++++++[/!]

[q topic=”atomic structure and drawing atoms”] Potassium has 19 protons, 19 neutrons, and 19 electrons. Following the Octet Rule for placing electrons in energy levels, which of the following arrangements is correct?

[c] Ten electrons in the first energy level, nine in the second.

[c*] Two electrons in the first energy level, eight in the second, eight in the third, and one in the fourth.

[c] Two electrons in the first energy level, ten in the second, and seven in the third.

[f] No. To represent the structure of electrons in atoms, keep in mind the capacity of each energy level (two electrons in the first, eight in the  second, and eight in the third). In Potassium, with 19 electrons, the first two electrons go into the first energy level. The next 8 go into the second energy level. The next 8 go into the third energy level. That leaves one electron for the fourth energy level.

[f] Nice job! In Potassium, with 19 electrons, the first two electrons go into the first energy level. The next 8 go into the second energy level. The next 8 go into the third energy level. That leaves one electron for the fourth energy level.

[f] No. To represent the structure of electrons in atoms, keep in mind the capacity of each energy level (two electrons in the first, eight in the  second, and eight in the third). In Potassium, with 19 electrons, the first two electrons go into the first energy level. The next 8 go into the second energy level. The next 8 go into the third energy level. That leaves one electron for the fourth energy level. 

[!]QUESTION 6 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”elements, compounds, molecules, formulas”]How many individual atoms are found in a molecule of CH4O?

[c]3

[c]4

[c*]6

[f] No. There are three elements in this molecule: carbon (C), hydrogen (H), and oxygen (O). The lack of a subscript next to the carbon and oxygen indicates one atom of each. The subscript “4” next to the hydrogen (H4) indicates that there are four hydrogen atoms. 4 + 1 + 1 = 6 total atoms. 

[f] No. You might have been confused by the 4 next to the H (H4). Here’s how it works: There are three elements in this molecule: carbon (C), hydrogen (H), and oxygen (O). The lack of a subscript next to the carbon and oxygen indicates one atom of each. The subscript “4” next to the hydrogen (H4) indicates that there are four hydrogen atoms. 4 + 1 + 1 = 6 total atoms. 

[f] Yes. There are three elements in this molecule: carbon (C), hydrogen (H), and oxygen (O). The lack of a subscript next to the carbon and oxygen indicates one atom of each. The subscript “4” next to the hydrogen (H4) indicates that there are four hydrogen atoms. 4 + 1 + 1 = 6 total atoms.

[!]QUESTION 7 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”elements, compounds, molecules, formulas”]What’s the smallest piece of a compound that still has the properties of that compound?

[c*]A molecule

[c]An atom

[c]An ion

[f] Yes. A molecule is the smallest piece of a compound that still has all of the properties of that compound. 

[f] No. Atoms are the building blocks of matter. But compounds (combinations of chemically bonded atoms) have properties that are very different from the atoms that make them up. The smallest unit of a compound to still have that compound’s chemical properties would be a molecule

[f] No. Ions are atoms that have lost electrons, and thereby gained an electrical charge. Compounds are combinations of chemically bonded atoms. The smallest unit of a compound to still have that compound’s chemical properties would be a molecule.

[!]QUESTION 8 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”ionic bonds”]The type of chemical bond that would result from the electron swapping shown below is a(n)

[c]covalent bond

[c*]ionic bond

[c]hydrogen bond

[f] No. Covalent bonds result when atoms share electrons (as opposed to swapping them, which is what is shown in this diagram. This type of swap is the basis for an ionic bond. 

07_NaCl bonding 4
An ionic bond

[f] Yes. In ionic bonds, atoms swap electrons. Electron swapping results in charged ions, which bond with one another because of their opposite electrical charges. 

07_NaCl bonding 4
An ionic bond

[f] No. A hydrogen bond is a bond between molecules. The kind of electron trading shown above results in charged ions, which bond with one another because of their opposite electrical charges. The resulting bond is an ionic bond (see below)

07_NaCl bonding 4
An ionic bond

[!] QUESTION 9 START+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++[/!]

[q topic=”ionic bonds”]What’s the charge on a calcium ion?

[c] It has no charge

[c] + 1

[c*] + 2

[c] -1
[f] No. The diagram shows a calcium ion with 20 protons, and 18 electrons (2 + 8 + 8 = 18). The charge on the ion is the number of protons, minus the number of electrons.
[f] No. The diagram is showing calcium with 20 protons, but only 18 electrons. The charge on the ion is the number of protons, minus the number of electrons.
[f] Excellent. The diagram is showing calcium with 20 protons, but only 18 electrons. Its charge has to be +2.

[f] No. The diagram is showing calcium with 20 protons, but only 18 electrons. The charge on the ion is the number of protons, minus the number of electrons.

[!]QUESTION 10 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”covalent bonds and structural formulas”]The bonds holding methane together are ___________  bonds.

[c]ionic

[c]atomic

[c]hydrogen

[c*]covalent

[f] No. If you look at the diagram above, you can see that the carbon and hydrogen are sharing electrons. The bond that involves sharing electrons is a covalent bond. 

[f] No. f you look at the diagram above, you can see that the carbon and hydrogen are sharing electrons. The bond that involves sharing electrons is a covalent bond. 

[f] No. Hydrogen bonds are bonds between molecules. If you look at the diagram above, you can see that the carbon and hydrogen are sharing electrons. The bond that involves sharing electrons is a covalent bond.

[f]Yes. If you look at the diagram above, you can see that the carbon and hydrogen are sharing electrons. The bond that involves sharing electrons is a covalent bond.

[!]QUESTION 11 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”covalent bonds and structural formulas”]The bond between the two carbon atoms in the diagram below is a(n)

[c]ionic bond

[c]single covalent bond

[c*]double covalent bond

[f] No. Ionic bonds involve atoms that have traded elecrons. In this structural formula diagram, the two lines between the carbon atoms (indicated by a C) indicate a double covalent bond, which means two shared pairs of electrons. 

[f] No.In this structural formula diagram, the two lines between the carbon atoms (indicated by a C) indicate a double covalent bond, which means two shared pairs of electrons. 

[f] Yes.In this structural formula diagram, the two lines between the carbon atoms (indicated by a C) indicate a double covalent bond, which means two shared pairs of electrons.

[!]QUESTION 12 ++++++++++++++++++++++++++++++++++++++++++++[/!] 

[q topic=”covalent bonds and structural formulas”]Which of the diagrams below is a structural formula?

[c]

[c*]

[c] CH4

[f] No. A structural formula shows the chemical symbols for the atoms in a molecule, and uses dashes to represent the shared pairs of electrons that connect these atoms. The structural formula was this one: 

[f] Yes.In this structural formula diagram, the two lines between the carbon atoms (indicated by a C) indicate a double covalent bond, which means two shared pairs of electrons. 

[f] No. “CH4” is a molecular or chemical formula. A structural formula shows the chemical symbols for the atoms in a molecule, and uses dashes to represent the shared pairs of electrons that connect these atoms. The structural formula was this one:

[x]Don’t worry about your score on this prequiz. However you did, just by having taken it you’ll learn more from the tutorials that follow. Please continue by reading below.

[/qwiz]

4. Next steps

Now that you’ve taken this practice quiz, please move on to the first tutorial in this series. Or, follow the other links below:

This Post Has 3 Comments

  1. Very good

  2. this is a cool website

  3. Thanks, Shamik. I’m curious about whether users like yourself are working on their own, or with a teacher. Let me know.
    Mr. W

Comments are closed.