Learning goals: Essential Chemistry for Biology

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1. Explain major terms related to Atoms and Elements

• Identify the location and charge of protons, electrons and neutrons.
• Define the terms atom, element, molecule and compound.
• Identify the elements corresponding to the following chemical symbols: C,H,N,O,P,S along with Na, Cl, K.
• Distinguish between atomic number and mass number.
• Explain what isotopes are and why they are useful.

2. Explain the relationship between electrons and chemical properties of atoms

• Explain the term electron shell and the relationship between electrons and energy.
• Explain why the outer most electron shell is important.

Comments:

Always remember: Electrons can gain, carry and loose energy! If you have had chemistry the electron shells are sometimes referred to as energy levels. Also as a rule of thumb. atoms with an outer most electron shell which is almost empty tend to give up those electrons to other atoms (example Na); atoms with an almost full outer most electron shell (examples O, Cl) tend to grab electrons from other atoms. If the outer most electron shell is 'full' then the atom does not easily react with other atoms(example He).

3. Distinguish between the main types of chemical bonds.

• Define "chemical bond" in terms of electrons.
• Distinguish between and give examples of compounds and molecules.
• Define what happens to electrons in the following types of bonds:
  • Ionic
  • Covalent bonds.
• Interpret the representations of molecules using molecular formulas, structural formulas, space filling and ball and stick models. Fig 2.9
• Define the terms reactant and product with respect to chemical reactions.

4. Discuss the major Life supporting properties of water and how they relate to hydrogen bonding.

• Define hydrogen bond and explain how they arise.
• Explain why hydrogen bonds are important.
• Sketch the electric charges on a water molecule. See figure 2.11.
• Explain the role of hydrogen bonds in water's
  • Cohesion
  • Ability to moderate temprature
  • The fact that ice floats.
  • Solvent properties

 

Comment: note that some substances dissolve very well in water or in the case of substances that do not dissolve in water, for instance sugar and cellulose, attract water molecules. Such substances are called hydrophilic. Substances that do not dissolve in water and do not attract water molecules are called hydrophobic, for instance wax and oil.

5. Distinguish Acids Bases and Buffers

• Explain what the pH scale measures. Note that the scale is based on powers of 10. See fig 2.17
• Distinguish between acids and bases in terms of change in hydrogen ion concentration.
• Explain what a buffer is and why buffers are important. Explan the bicarbonate buffering system in the blood.

Discussion question: The various properties or characteristics of water as a liquid (the fact that water is cohesive, a great solvent for polar molecules and ions, holds a lot of heat etc..) are often called emergent properties. What does this term mean? What are some other 'properties' in the world around us that might be considered emergent properties?

6. Define the following terms:

pgd 01/23/05