Fundamentals of Chemistry, Day #1 Lecture Notes

Chemistry AS403 – Lecture 1 Notes: Fundamentals of Chemistry

Okay, let the good times roll. Today we cover the basic tools one needs to start taking a crack at chemistry.

Let’s start with VOCABULARY, some simple definitions that will put all of us on the same page as the game gets underway. In alphabetical order:

• Accuracy = closeness of a measured value to the true value
• Atom = the smallest particle of an element (Gr. atomos = “uncut”)
• Chemistry = a science that investigates the composition of materials and how their properties change by their environment
• Compound = substance combining fixed proportions of 2 or more elements
• Density = ratio of an object’s mass to its volume
• Element = a substance that cannot break into a simpler one
• Energy = a quality allowing an object to do work. The two main classes:
• Kinetic = energy in a moving object
• Potential = stored energy (which can be converted to kinetic type)
• Heat = energy that is transferred among objects with different temperatures
• Law = a broad generalization known by experimentation to be true for all people and all times
• Mass = the quantity (NOT weight!) of a given substance
• Matter = anything that occupies space and has mass
• Mixture = material combining variable proportions of 2 or more substances
• Molecule = Smallest particle of a compound
• Precision = closeness of repeated measurements to each other
• Property = characteristics unique to a given substance. Two types are:
• Chemical = trait that can change as a substance reacts with others
• Physical = trait that can be observed without changing the substance
• Specific gravity = ratio of a substance’s density to that of water
• Temperature = property proportional to the average kinetic energy
• Theory = a well-tested explanation of a natural phenomenon
• Weight = the force with which a substance is attracted by gravity
  

Once we have a common lingo, we need some other COMMON PROCEDURES. Chemists, indeed all scientists, use the following tools each and every day. The “Big Three” pieces in the tool kit are the International System of Units (SI), Significant Figures, and Scientific Notation.

The SI scheme offers standard units of measurement for seven basic quantities. The most common in the chemistry laboratory are for length (meter, m); mass (kilogram, kg); time (second, s); temperature (kelvin, K); and amount (mole, mol). The base units can be modified by adding prefixes and suffixes, the most typical of which are mega (10⁶, M); kilo (10³, k); centi (10^-2, c), milli (10^-3, m), micro (10-6, m), and nano (10^-9, n). Conversion factors are used when necessary to convert between the various units. Examples for length and volume (with derived units of length cubed) include:

1 m = 100 cm = 1000 mm

1 m³ = 1000 L (where L = liter)

1 L = 1000 cm³ = 1000 mL

Significant figures are those which have been accurately derived by careful measurements. The number of significant figures in a measured value is equal to the number of digits known for certain plus one that is not totally certain. The higher number of significant figures, the greater the degree of precision.

Scientific notation is a shortcut for writing very large or very small numbers. In science, the standard use is to write numbers to base 10, using exponents. As an example, an electron (a very small subatomic particle) has a mass of about 0.000 000 000 000 000 000 000 000 000 000 910 kg. In scientific notation, this number is rendered as 9.10 x 10⁻³¹ kg. Simple rules for working with exponents allow scientists to manipulate numbers easily when working with minute samples and very rapid reactions.