Download The Atomic Theory

MY INFO The Atomic Theory
Developed by John Dalton
1. Each element is composed of very small particles
called atoms.
2. All atoms of an element are identical, atoms of
different elements are different.
3. Atoms of an element are not changed into different
atoms by chemical reactions; atoms are not created
or destroyed by chemical reactions.
4. Compounds are formed when atoms of more than
one element combine.
EQ: What is important about atoms?
 What does an atom look like?
 How are ions formed?
 What happens to atoms as matter changes state?
What does an atom look like?
 modern atomic model
 electrons move around
the nucleus in a "cloud"
of energy
 valence electron
 the outermost electron (s)
that circle the nucleus of
an atom.
 valence electrons are very
important in the bonding
of atoms!
How are ions formed?
 Ions are formed when an atom gains or loses an
electron.
 atoms in a solid
 Very close together, they
do not have much energy
but still can move
slightly.
 As the atoms of a solid
gain energy, they begin
to move more and spread
out.
 atoms in a liquid
 Still quite close to each
other, but they have
enough room and energy
to flow freely past each
other.
 As the atoms of a liquid
gain energy, they move
more quickly and spread
out.
 atoms in a gas
 These atoms have A LOT
of energy – they are
spread very far apart and
move quickly. This is
why a gas has no definite
shape of volume.
 atoms in a plasma
 A collection of
electrically charged
particles that take the
form of gas-like clouds.
(ionized gas)