Download The Atom - Hickman Science Department

The Atom
What are Atoms?
Atoms are the basic building blocks of matter that
make up everyday objects. A desk, the air, even
your body is made up of millions of atoms.
There are 90 naturally occurring kinds of atoms
and 25 more that are man-made.
The Periodic Table of the Elements list these atoms
– from smallest to largest.
The idea of the atom
was first devised in
530 B.C. by a Greek
named Democritus.
He was born about 460 B.C.
and died at more than a
hundred years of age. It is
said that from then on he
spent his days and nights in
caverns and sepulchers, and
in order to master his
intellectual faculties, he
blinded himself with burning
glass. This story, however, is
discredited by the writers who
say he wrote books and
dissected animals, neither of
which could be done well
without eyes.
Science TV
Atom - Democritus
Review of Atomic Structure
The nucleus was discovered in 1911 by
Ernest Rutherford. Here’s how he did it:
Atom – Rutherfords Experiment
Let’s take a look again at that nucleus…
Science TV
Atom - Nucleus
The nucleus is the massive center of the atom.
It was discovered in 1911 but it took another
21 years of experimenting to identify what it
was made up of.
Protons
Neutrons
Scientists thought that there was nothing
smaller than the proton in the nucleus of the
atom.
In 1968 scientists discovered new particles
inside the proton. They called these particles
quarks.
There are three quarks in each proton. Quarks
are held together by other particles called
gluons.
In the neutrons they found
the same thing…..
Quarks and gluons.
So, in summary, the center
of the atom contains two
different particles called
protons and neutrons (which
are made of quarks). This
center is called the
nucleus. Around the
nucleus electrons are found.
Electrons are extremely small and very light. It
is easy to strip electrons off of atoms and use
them for electrical power and in devices like
TV sets
Science TV
Atom - Electrons
Most of an atom consists of ______________ ?
Science TV
Atom – Scale of the atom
Analogy…….. The Meadowlands
So how many protons, neutrons, and
electrons does an atom
exactly have???
Welllllll, it all depends on which one of the 115 (or so) atoms it is….
What pattern
do you see
here???
Look closely…..
In an atom there will always be the same number of
protons (+) as there are electrons (-).
As a result, most atoms are electrically neutral – the
positives cancel out the negatives.
Sodium (Na)
Gold (Au)
Electrons are so light they are not figured in on the mass of an
atom. (Kind of like having an ant on your arm when you weigh
yourself. The ant really isn’t adding significant weight to you).
Although more details of the atom were discovered in the
1900’s a man named John Dalton came up with something
called the Atomic Theory in 1808. Dalton was the guy that was
able to link what was known about atoms to the elements.
Dalton was an English
school teacher and
scientist .
Science TV
Atom - Dalton
Here’s what Dalton’s atomic theory said:
1. Every element is made of atoms - piles of paper clips.
2. All atoms of any element are the same - all the paper clips in the pile
are the same size and color.
3. Atoms of different elements are different (size, properties) - like
different sizes and colors of paper clips.
4. Atoms of different elements can combine to form compounds - you
can link different sizes and colors of paper clips together to make new
structures.
5. In chemical reactions, atoms are not made, destroyed, or changed no new paper clips appear, no paper clips get lost and no paper clips
change from one size/color to another.
6. In any compound, the numbers and kinds of atoms remain the
same - the total number and types of paper clips that you start with are
the same as when you finish.