Name_________________
Date______________
The
Basics of the Atom
From How Atoms
Work by Craig
C. Freudenrich, Ph.D.
http://science.howstuffworks.com/atom.htm/printable
In 530 BC Democritus, an _______________ Greek, originated
the concept of the “atom” as the smallest _______________ of
matter. To the ancient Greeks, this
idea was very poetic and _______________, but of course there was no _______________
that it had any reality.
|
proof particle philosophical ancient |
Modern atomic theory was _______________
in 1808 by John Dalton, an English school teacher and scientist. This theory still has the following _______________:
·
Every _______________ is made of atoms
·
All atoms of any element are the
_______________ (size, mass and other properties)
·
Atoms of different elements are
_______________ (size, mass and other properties)
·
Atoms of different elements can
_______________ to form compounds.
·
In _______________ reactions,
atoms are not made, destroyed, or changed
· In any chemical reaction, the numbers and kinds of atoms
remain the same.
Dalton thought of atoms as tiny balls
with _______________ on them. These “hooks” would allow atoms to connect
together
to form _______________. In
this theory hydrogen atoms would “hook
up” with oxygen atoms to form _______________.
|
element combine principles different water chemical proposed same hooks compounds |
For most of the 19th _____________ scientists continued
to think of atoms as _____________ spheres (Dalton’s
model) until a series of experiments conducted by Ernest Rutherford
demonstrated that most of an atom is actually _____________
space!
Rutherford and other 19th
century scientists did a lot of experiments involving _____________ which we now know of
as streams of subatomic particles.
Rutherford _____________ thin foils of gold with alpha rays and _____________
the
results. Most of the alpha particles
passed straight through the _____________ and only a very
small _____________ of them had their paths deflected. Rutherford reasoned that the alpha particles
with _____________ paths were passing through empty space. And
that whatever caused the alpha particles to _____________ was obviously very
small.
Another British scientist named J.J.
Thompson had already _____________ the
electron, so Rutherford came up with a new model of an atom. Instead of
a Dalton’s solid _____________ Rutherford’s atom consisted of a tiny _____________
surrounded by
electrons which revolve around the nucleus the way planets _____________
around their
sun.
|
century revolve recorded ball radiation percentage nucleus
bounce new discovered bombarded gold empty solid straight |
In 1913 the Danish _______________ Niels Bohr came up with a
slightly more advanced _______________ for
the atom. Neils Bohr was one of the _______________
of a new
branch of physics known as _______________ Mechanics. Bohr reviewed a series of _______________
that recorded
the light spectrums given off by various elements exposed to electrical or heat
energy. The spectrums (or wavelengths)
of different _______________ conformed to certain _______________
patterns.
Studying these patterns Bohr’s _______________ was that electrons
could only orbit an atomic nucleus at certain energy levels and that the number
of possible energy levels is _______________.
|
founders Quantum intuition model experiments regular limited elements physicist |
Bohr’s model had some important _____________ for basic
chemistry. Instead of Dalton’s hooks -
electrons were what connected _____________ atoms together to
form _____________ compounds.
According to Bohr an atom’s ability to _____________
with other
atoms depends on the number of electrons in its outermost energy level. Atoms
whose outermost energy levels are “full” of _____________ will not react with
other _____________.
Atoms whose outermost energy levels are not _____________
will give,
take, or _____________ electrons from other atoms and in that
process become bonded _____________. For example: helium atoms have a _____________
outer “shell”
of electrons and therefore helium atoms are chemically “inert”. (They do not _____________
easily with
other atoms). Oxygen atoms, on the
other hand, are very _____________.
|
different bond react atoms together implications reactive
molecular complete electrons complete share |
Some Definitions
- atom - smallest unit of an element that _____________ its
chemical properties
- compound - _____________ that can be chemically broken down into elements
- electron – negatively charged particle
_____________ an atom’s nucleus
- element - substance that _____________ be
broken down by chemical reactions
- ion - electrically _____________ atom (i.e., excess positive or negative charge)
- molecule - smallest unit of a _____________ that
keeps its chemical properties (consists of two or more atoms)
- neutron - particle in the nucleus of
an atom with no _____________
- nucleus - dense, central _____________ of an
atom (made of protons and neutrons)
- proton - particle
in the nucleus of an atom with a _____________ charge
|
charged
positive orbiting charge keeps substance core compound cannot |