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 * AP Biology** **Name _**
 * Chapter 2 Guided Reading Assignment **

This chapter is a review of basic chemistry – we will be going through this chapter very quickly. If you have any problems – please see me before school for additional help.

1. Contrast the term element with compound.
 * An element is an atom, or molecule composed of a single type of atom, for example carbon. A compound is a molecule made consisting of two or more different elements, or atoms, for example carbon and oxygen make carbon dioxide. **

2. Label the diagram below and define the terms that you label.
 * [[image:bealbio/chem_chapter_2_Q_2_image.jpg caption="chem_chapter_2_Q_2_image.jpg"]] ||
 * chem_chapter_2_Q_2_image.jpg ||


 * Electrons are stable subatomic particles with a charge of negative electricity. Protons are stable subatomic particles occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign (+). Neutrons are subatomic particles of about the same mass as protons but without an electric charge. The nucleus is the middle of any atom and contains all of the mass of the atom. It consists of protons and neutrons. The cloud of negative charge is simply a snapshot compilation of the two electrons overtime. **


 * A: **
 * ** The blue dust symbolizes a cloud of negative electric charge created by a snapshot compilation of 2 electrons overtime. **
 * ** The (+) indicates protons **
 * ** The brown ball indicates neutrons **
 * ** The nucleus is the protons and neutrons together **

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 * B: **
 * The (+) indicates protons **
 * ** The brown ball indicates neutrons **
 * ** The nucleus is the protons and neutrons together **
 * ** The (-) is indicative of electrons **

3. Contrast the terms atomic mass and atomic number.
 * The atomic mass is the sum of protons and neutrons in the nucleus whereas the atomic number is merely the number of protons in the nucleus. **

4. What is the difference between the terms atomic mass and atomic weight? Atomic mass is the number of protons and neutrons of a single isotope. However, atomic weight is the average mass of the element between all of its isotopes, based on their abundance in the natural world.

5. What is an isotope and what is “special” about radioactive isotopes? Isotopes have different numbers of neutrons in them relative to the number of protons. Thus, Carbon 14 (6protons,8neutrons) is an isotope, while Carbon 12 (6protons,6neutrons) is not. Radioactive isotopes are unstable because their nuclei decay spontaneously, releasing energy and subatomic particles. 6. Explain how radioactive tracers are used in science? Radioactive tracers are isotopes that are put into solutions to create various new compounds. Then, when the tracers decay, they react with scintillation fluid to produce flashes of light, which are then measured and can be used to calculate the amount of compound produced. They are widely used in the medical field for various purposes as explained in this [|video.]

7. Explain how the movement of electrons relates to the concept of potential energy – use the diagram below to help answer the question.


 * [[image:bealbio/chem_chapter_2_Q_7_image.jpg caption="chem_chapter_2_Q_7_image.jpg"]] ||
 * chem_chapter_2_Q_7_image.jpg ||

8. Explain how the movement of electrons relates to the concept of potential energy – use the diagram below to help answer the question.

9. What determines interactions between atoms? Why are valence electrons important?

Interactions between atoms are determined by electron configuration.Valence electrons are important because they determine chemical behavior.

10. Define the following terms: a. Chemical bond - The action of an atom being binded to another atom through electrical attraction

b. Covalent bond- This is a type of bonding where the, instead of one atom taking another's electrons, they share and form a more stable bond. c. Single bond When a pair of shared valence electrons/ single covalent bond d. Double bond When electrons share two pairs of valence electrons to form two covalent bonds

An atoms bonding capacity

f. Electronegativity The attraction of a particular kind of atom for the electrons of a covalent bond.

g. Nonpolar covalent bond A type of covalent bond in which electrons are shared equally between the two atoms of the same electronegativity



h. Polar covalent bond A type of covalent bond between atoms that have a different electronegativity so the shared electrons are pulled closer to the stronger electronegative atom



11. What is the difference between a structural and molecular formula?

A structural formula indicates how the atoms are bonded to one another, where atoms are joined by lines representing covalent bonds. It is also a type of molecular notation. A molecular formula shows the number of the atoms that makes up the molecule. A molecular formula also indicated the numbers and types of elements in one molecule of a substance.

Example of structural: H -- H Example of molecular: H subscript 2

12. How do ionic bonds compare with covalent bonds? Ionic bonds are when cations and anions attract each other. So, atoms are attracting each other based on their charges. the transfer of an electron is not the formation of a bond, it just allows a bond to form because it results in two ions. And any two ions of opposite charge can form an ionic bond. Covalent bonds make bonds by sharing a pair of valence electrons to fill up their valence shells which thus makes a molecule. 13. Compare and contrast hydrogen bonds and van der Waals interactions.

A hydrogen bond forms when a hydrogen atom covalently bonds to one electronegative atom is also attracted to another electronegative atom. Van der Waals interactions occur only when atoms and molecules are very close together. It is when positive and negative charge enabled all atoms and molecules to stick to one another. / These two are similar b/c they are both weak bonds, they can form between molecules and different regions of a single large molecule, and they reinforce the three-dimensional shape of a large molecule.

Van Der Waals Hydrogen Bonds

14. Based on the reading, what is an example, in a living system, of how molecular shape is critical? Endorphines that are naturally in the synapses of the brain to endorphine receptors the molecules at the end of the chain of a natural endorphine is copied by morphine and absorbded the same way. Without the similar shape, morphine would have no practical use.

15. Define a dynamic chemical equilibrium in terms of quantities of reactants and products. This is a critical concept! This is the point at which, the reactants and the products of a given reaction reach a ratio in which they are equal.