Transcript AM-1 Power point - Moline High School

AM1: Atomic Structure
Chapters 38 and 39
Atom
 Atom-The smallest division a particle can
be divided into and still maintain the
properties.
The Development of the Atomic
Theory
• First theory of the atom:
• Greek Philosopher
Democritus 400 BC
- “atom”
(means- “unable to be cut
or divided”)
Second try
• John Dalton in 1808
1. Atoms can not be divided
2. All atoms of a given element
were exactly the same
3. Atoms of different elements
could join to form compounds
• Used the law of definite
proportions.
• Says a chemical
compound always
contains the same
elements in exactly the
same proportions.
• Ex. water
Third try
 J.J. Thomson in 1897
- First to say atom could be
broken into smaller parts
-He discovered the “electron”
-Theorized that an atom was
made of negative particles
scattered throughout positive
matter.
- He called this the
-“plum pudding theory”
 Thomson found this
“negatively” charged
particle when he did
experiments with the
cathode ray
http://www.youtube.com/watch?v=O9Goyscbazk
• When a magnet was
brought near the ray it
deflected away from the
magnet! There had to be
something in the atoms that
was negatively charged!
Fourth try
 Rutherford 1908
- Majority of atom is empty
space
-With a large dense positive
center in the atom
--the nucleus
- the negatively charged
electrons orbit around the
nucleus
experiment
http://www.youtube.com/watch?v=5pZj0u_XMbc
• “Rutherford” performed the “gold-foil experiment”
Shot photon beam at a gold foil. Most of the beams
went straight through, but some were deflected off to
the side.
Extra information found!
 Chadwick 1935
-found the neutron in the nucleus
- Neutron-An electrically neutral
particle found in the nucleus of
an atom
Bohr Model-“Planetary Model”
 Electrons orbit in
energy levels
Subatomic
Particle
Location
Charge
Mass (AMU)
Proton
Nucleus
+
1
Neutron
Nucleus
0
1
Electron
Outside the
nucleus
-
0
 Proton
Element
 Element-Substance made of only one kind of
atom.
Periodic Table of Elements
 Periodic Table of Elements-Chart that lists
elements by atomic number and by electron
arrangement
Element Key
Atomic Number = number of protons
Proton-A positively charged particle
found in the nucleus of atoms
6
Element symbol
C
carbon
12.011
Element name
Average atomic mass =the average mass
of all the isotopes of an element, this is
weighted
Mass number- the whole number based on the average
atomic mass.
Ex. Carbon would have the mass number of 12.
It is equal to the number of protons + neutrons found in the
nucleus.
Isotope
 Isotope-A form of an element that has the
same number of protons but a different number
of neutrons.
Ion
 Ion-Charged atom due to the loss or gain
of electrons
 If an atom gains electrons, becomes negatively
charged (anion)
 If an atom loses electrons,
becomes positively charged
(cation)
Explanation of the Atom
 WKRP – Venus
explains the atom
 http://www.youtube
.com/watch?v=hhb
qIJZ8wC