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Chemistry is the study of matter, which is anything that hass mass and volume. You are made up of matter, as is
your books, sneakers, etc. Even the gases that make up our atmosphere are matter. Chemistry is the branch
of science that is concerned with the composition of matter and the changes that occur to it.
This topic is an introduction to the foundations of matter, in terms of; basic classifications, how it was originally
viewed and current thoughts, and the structure of the atom.
I. EARLY STUDIES OF MATTER
The early studies of matter starts with the Greeks! They viewed all matter to be composed of particles from four
elemental substances
This view was held until the 1600s when a man named Robert Boyle identified Gold
and Silver as being elemental in themselves (the most basic)..and not made up of what the
Greeks termed as an elemental substance
John Dalton built on
Boyle's work and in the 1700s theorized that the basic unit of matter is called the ATOM and summarized his findings into
four postulates
1. All elements are composed of indivisible atoms
2. All atoms of a given element are identical
3. Atoms of different elements are different and have different masses
4. Compounds are formed by the combination of atoms of different elements
That's great...atoms make up elements...elements
make up compounds..but what is an ATOM composed of?
J.J Thomson discovers the electron..click on the tube!
Thomson proposed that the electrons might be imbedded in the atom...small negatively charged particles in a large positive
sphere..he called this the Plum Pudding Model
Rutherford discovers the nucleus...click on the man!
Modern Atomic Theory
Neils Bohr proposed a model of the atom showing a dense nucleus with electrons found
in surrounding orbits. He later performed work on the hydrogen atom and comcluded that electrons can jump from
a lower energy level (one closer to the nucleus) to a higher energy level by absorbing a specific amount of energy; this
specific amout is equal to the energy difference between the two levels. click on the Professor to find out more!
The Wave Mechanical Model advances the study of energy and atomic structure by modifying
the atomic model. Energy had been view as waves and matter as particles, however, in the late 1900s, energy and matter
were viewed as acting as both..NOT as seperate entities, but with a dual nature. In fact, energy is viewed to exists
in discrete packets called quanta.
This new model places the electrons not in specific orbits (as in Bohr's Model), but as packets with distinct amounts
of energy moving in orbitals
An Orbital is described as a region in which an electron of a particular amount of energy might be found.
The Wave Mechanical Model is our current view of Atomic Structure...
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