Dr. Kent McCorkle, or "Dr. Kent' to his student, has helped thousands of students be successful in chemistry.

# Chemistry Lesson: Average Atomic Mass Calculations

[View the accompanying Atomic Mass Practice Problems Part I here.] Atomic Mass The atomic mass is an experimental number determined from all of the naturally occuring isotopes of an element. As we saw in our lesson on atomic structure, not all … Read More

# Chemistry Lesson: Unit Analysis (Unit Conversions, Dimensional Analysis)

Converting Units When we need to convert between units (for example, converting minutes to seconds) we use conversion factors. Conversion factors are a ratio that specify how one unit of measurement is related to another unit of measurement.  For example, … Read More

# Chemistry Lesson: Structure of the Atom – Protons, Neutrons & Electrons

Basic Structure of the atom The atom is very tiny, having a diameter of about 10-10 meters. Keep in mind that’s like saying 0.0000000001 meters, or about one-billionth of a meter across! But within this already extremely small atom is … Read More

# Chemistry Practice Problems: Scientific Notation

[View the accompanying Lesson on Scientific Notation here.] [Download the accompanying PDF worksheet.] Convert the following numbers into scientific notation: 1.  192 Gs 2.  0.00478 fm 3.  50800 qt 4.  390.0200 K 5.  0.08200 µm 6.  4000 °F   Convert the following … Read More

# Chemistry Lesson: Scientific Notation

[View the accompanying Scientific Notation Practice Problems here.] What is Scientific Notation? Scientific notation is a method of writing really large or really small numbers in a more concise form that removes all of the extraneous zeroes.  For example, 0.0000000072 … Read More

# Chemistry Lesson: Significant Digits & Measurements

[View the accompanying Significant Digits & Measurements Practice Problems here.] Why Significant Digits? Significant digits (also called significant figures or “sig figs” for short) indicate the precision of a measurement.  A number with more significant digits is more precise.  For example, … Read More