Chapter 11
The Atomic Nature of Matter
Atomic Hypothesis
• What is smallest divisible amount of matter
has been pondered for thousands of years.
• Aristotle disagreed with the idea of atoms and
pushed the idea of matter beings composed
of 4 elements.
• During the early 1800’s atomic theory was
reintroduced by John Dalton.
Atomic Hypothesis
• In 1827 Robert Brown hypothesized that these
invisible atoms moved and collided, now
called Brownian Motion.
• 1905 Albert Einstein presented a detailed
explanation of atomic nature that allowed
atomic masses to be derived.
The Elements
• All things are made of a combination of 88
different elements.
• There are a total (as of 2001) 118 different
elements.
• The most common element is Hydrogen,
which stars use a fuel.
• Elements that comprise all livings things are
Hydrogen, Carbon, Oxygen, and Nitrogen.
Elements
• Atoms are incredibly small.
• Atoms are numerous: there are about 1023
atoms in a gram of water.
• Atoms are ageless: atoms are continually
recycled into other materials.
• Atoms get around: Since atoms are
constantly in motion they have an endless
ability for diffusion.
Atomic Models
• Since we cannot see atoms we have to make a
model.
• In 1911 Ernest Rutherford and Niels Bohr
came up with the most common atomic
model.
Atomic Imagery
• Atoms are too small to ever been seen with
visible light.
• Using high frequency electron beams pictures
of element chains were photographed in the
1970.
• Using a scanning tunneling microscope can
revel the surface topology of atoms.
Electrons
• Electron is the Greek word for amber.
• Using a cathode-ray tube the electron was
discovered.
• An electron has a negative charge and very
little mass.
Atomic Nucleus
• Using an emitting alpha particles at a piece of
thin gold foil caused some of the beam to
scatter, while most of it passed through the
material.
• Scattered particles struck the nucleus of the
gold atoms.
• Electrons orbit the nucleus at a huge diameter.
The Nucleus
• Though small, subatomic particles have strong
electrical fields.
• These fields keep no bonded atoms from
interacting.
Proton
• The nucleus’s active particle is the Proton.
• Protons are 2000 times more massive then
electrons.
• Electrons stack into shells around the nucleus
of an atom.
• When an atom has a complete shell it
becomes nearly chemically inert
Neutrons
• Neutrons are electrical inert and mass to the
nucleus of the atoms.
• Most atoms have a set number of neutrons,
but this is not a set rule.
• Isotopes are atoms that have an more or less
neutrons.
Quarks
• Quarks are fundamental particles that build
electrons, protons, and neutrons.
• Quarks exists only in large particles and not
individually.
Elements, Compounds, Mixtures
• Fundamental atomic compositions are
elements.
• Combinations of elements are called
compounds. The atoms share electron bonds.
• Substance that mix, but do not bond are
called mixtures.
Referances
• http://www.colorado.edu/physics/2000/apple
ts/