Introductory Concepts, Page 5

Law of Conservation of Energy:

The Law of Conservation of Energy says that energy can neither be created nor destroyed. In a chemical process, the energy in the system may change appearance, but the total will be constant. This law is true for traditional reactions such as those done in a chemistry lab. This is one of the fundamental ideas of all chemical processes. If a reaction were to occur that involved burning a 5 pound log, the log would initially contain a specific amount of energy. After the burning process is completed, the log will be gone. In its place a number of other substances will have formed, such as ash and gases, along with some heat. The total energy content of the ash, gases, and heat would add up to the same amount of energy that was originally present in the log. Often the energy changes form. It may appear as heat, light, electricity, or many other options. Still, the sum total of energy, before and after the process, will be equal, regardless of the form that it is in.

Law of Conservation of Mass-Energy:

The Law of Conservation of Mass-Energy says that the sum total of mass and energy in the Universe is constant. Mass can be converted into energy and energy can be converted into mass. However, the loss of one will be exactly balanced by the creation of the other. This law was developed to take into consideration the mass-energy conversions that occur in nuclear processes. Mass and energy do not undergo conversions during the more traditional processes that take place in a chemistry lab. The need for this law only became obvious after Einstein determined that matter and energy were interchangeable. That idea is the core concept of nuclear processes and is derived from the equation

Mass:

Mass is the measure of the quantity of matter. It is the only universal method of measuring the amount of a substance in a given sample. Weight is frequently confused with mass. Because Weight varies with the pull of a gravitational force, it is not constant. Weight would not be a good way to measure the quantity of matter. In a lab setting, substances are massed, they are not weighed. Anything that has Mass will exhibit the qualities of Inertia.

Mass Number:

Mass Number is the sum of the protons and neutrons within a nucleus, or Mass Number is the sum of the nucleons within a nucleus. The term is somewhat deceptive, because it sounds as if it should give the mass of a nucleus. It does not do that. Instead, it indicates the number of objects within the nucleus. Since the majority of the mass of an atom is located within the nucleus, this term refers to the area of concentrated mass in an atom by indicating the number of objects in the nucleus. By universal agreement the symbol for the Mass Number is the upper case letter A. If an atom contains 7 protons and 9 neutrons, then it has a mass number of 16, or A = 16. Note that in this instance, the atomic number is 7, or Z = 7.

Matter:

That which takes up space and has mass.

Millikan Oil Drop Experiment:

This experiment was developed by Robert Millikan. It was designed to measure the charge on a single electron.

By placing negative charges on oil drops he was able to suspend them between two charged plates.	His experimental set-up allowed him to regulate the magnitude of the charge on the two plates.
When the electrostatic forces drawing the charged oil drops upwards equaled the gravitational forces pulling the electrons downward, the oil drops floated in mid air. As he adjusted the magnitude of charge on the plates, Millikan observed that all of the oil drops were suspended by quantities of charge that were multiples of a single number.
He concluded that this single smallest amount of charge needed to suspend	the oil drops corresponded to the charge on one oil drop.

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