Download The Development of Atomic Theory

What is this?
What is an atom?
Atoms are the basic unit of matter
All matter is made up of tiny atoms
Atom
Smallest Unit of an Element – made of
subatomic parts
Molecule
Atom
O
Oxygen
H
H
Subatomic Parts
Subatomic Parts
Draw a basic sketch of an
atom
Nucleus:
Dense/Heavy but tiny part of atom
Found in center of an atom
Electron cloud
Around nucleuselectrons fly
around
http://www.youtube.com/
watch?v=pV822HfqT44
There are two subatomic
particles that make up the
nucleus…….
THE PROTON
+
p
•Located in the
nucleus
•Has mass of : 1 amu
• Positive Charge: +1

°
N
THE NEUTRON
• Located in the
nucleus.
•Has mass: 1 amu
• Neutral Charge:
0 charge
Nucleus is held
together by a
strong nuclear
force
http://www.youtube.com/
watch?v=pV822HfqT44
Atomic Nucleus Summary
The nucleus is a dense area at the center
of the atom
•Protons and neutrons are found in the
atomic nucleus
Electron cloud
http://www.youtube.com/
watch?v=pV822HfqT44
THE ELECTRON
e
• Found in the
electron cloud
•Almost no mass:
0 amu
•Negative: -1 charge
½ Football Field
50
Nucleus
Outer
Edge
of
Atom
End Zone
Atoms are a lot of empty space!
If we blew up an atom to the size of a dime,
the electrons would be as far as ½ football
field away!
Electrons Summary
Electrons have a relatively
small mass compared to
protons and neutrons
Electrons are found far away
from the nucleus in an area
called the electron cloud
Electrons have a negative
charge
Subatomic Particles (Draw this)
Proton
Location in
the Atom
Mass
Charge
Neutron Electron
How small is an atom?
Atoms are TINY!
20 million hydrogen atoms would
fit inside the period at the end of
this sentence.
You are made of billions and
billions of atoms
WATCH BILL NYE>>>>>>>>>>>
Protons
+
p
Positive
+1
Neutrons Electrons

°
N
e
Neutral Negative
0
-1
ATOMS HAVE A NEUTRAL CHARGE
The number of protons = the number of
electrons
Neutrally charged Atoms will have the
same number of electrons as protons
How can I tell which atom is which
element?
Every atom of an element has an
ATOMIC SYMBOL- the letters
representing the element Au,
Ca etc.
How can I tell which atom is which
element?
Every atom of an element has an
**ATOMIC NUMBER – the number of
protons + in an atom. Tells us what
element the atom is.**
Like a SS# for an element-unique
Each element has a unique atomic
number
Example Carbon’s atomic number is
6, but Boron has an atomic number of 5
Every atom has an…..
ATOMIC MASS (Mass #) – the
number of protons + plus
neutrons 0 in an atom.
Example Carbon’s atomic
number is 6, but its atomic
mass is 12 6 protons and 6
neutrons
+
P
e-
+
P
0
N
What is the
atomic
number of
this atom?
3
+
P
e-
e-
Calculating Mass/Neutrons etc.
Element Atomic Mass
#
#
As
33
75
How many Electrons
neutrons? ?
42
78
Cs
55
133
Ti
22
26
N
7
11
48
14
23
12
Na
7
33
55
22
7
11
Review of Atomic Structure
What is the basic unit of matter?
• Atom
What are the 3 subatomic particles?
• Proton, Neutron, Electron
What’s the electrical charge of a proton?
• Positive (+)
What’s the electrical charge of a neutron?
• Neutral
What’s the electrical charge of an electron?
• Negative (-)
How in the World
Did They Figure All
this Out!?!
(5+ people)
1.Democritus
(450 B.C.)
•Came up with the idea
that matter is
composed of “tiny,
indivisible particles”
•Named them atomos
(Greek)
2. John Dalton (1766-1844)
•Dalton thought
that atoms were
hard, round, solid
balls
(like marbles)
First atomic
model
3. J. J. Thomson (1856-1940)
•Discovered and
named electrons
•He defined electrons
as particles with a
negative charge
4. E. Rutherford
(1871-1937)
Discovered and named
the nucleus
Protons and mass
concentrated at center
of atom
5. Niels Bohr
(1885-1962)
Discovered that
electrons exist in
energy levels
Electrons only have
certain energies – they
are quantized
•
Build
An
Atom
–
be
creative
Tips:
• Those with an atomic number of 5 or less will need to
build larger scale particles, compared to those with
atomic numbers above 5
Look at examples up front, or use your own method
• Guidelines: Don’t make models too small
• The electron orbits should get bigger as you add them
(see example)
• Keep all electrons same color bead/ clay/ material etc.
• All protons should be one color/type
• All neutrons should be one color/type
Make sure you attach a string 1 to 2 feet long to hang
from ceiling.