Download Atomic Structure

Atomic Structure
Chemistry: Chapter 4
Atoms
•Building block of matter
•Cannot be seen
•Known to exist through
indirect evidence.
Gathering information w/o
actually seeing or touching the
object. Used to develop a
mental picture or model.
Ex. gravity
History of the atom
overview
 http://www.nobeliefs.com/atom.htm
http://www.chalkbored.com/lessons/chemistry-11/atomic-models-handout.pdf
Greek
Model
•2400 years ago, Greek
philosopher Democritus
•1st to use the term “atom”
meaning “indivisible” or “not to
be cut”
•Ancient Greeks believed matter
was made of 4 basic elements:
fire, air, water, and earth
Dalton’s
Model
•Early 1800’s, English
chemist, John Dalton
•Meteorologist
•Developed the atomic theory
1.All elements are composed of atoms.
2.Atoms of the same element are identical.
3.Atoms of different elements are different.
4.Compounds are formed by joining 2 or
more atoms.
Thomson’s•1897
•Proved atoms were made up
Model
of even smaller particles
•Discovered corpuscles
electrons
•Model called “plum pudding”
Rutherford’s •1908
Model
•Discovered that atoms
have dense, positively
charged nucleus
•Fired charged particles at
gold foil, some went through
while others were deflected.
Subatomic •Protons
particles
Positively charged; +1
In the nucleus
Distinguishing
Characteristics:
• Mass
• Charge
• Location
•Neutrons
No charge
In the nucleus
•Electrons
Negative charge; -1
Outside the nucleus
Atomic
Number
Mass
Number
or
Atomic
mass
•Number of p+ in the nucleus
•Each element has a certain
number of p+
•Also equal to the number of e•Sum of p+ and neutrons
•Mass # = atomic # + neutrons
3
Li
7
Atomic #
Chemical symbol
Mass #
Isotopes
•Atoms of the same element
•Have different number of
neutrons, but the same number
of protons & electrons
•They have the same atomic
#,but different mass # because
of the # of neutrons
•Ex. (O-16, O-17, and O-18)
Each O has 8 protons, but the
neutrons vary
Bohr’s
Model
•1913
•Discovered that electrons
move in energy levels (orbits)
around the nucleus
•Called the “solar system
model”
Summary of history of the
atom
 http://www.aasd.k12.wi.us/west/science/b
artel/Chemistry/Ch3/History%20of%20At
om%20Notes.pdf
 http://www.footprintsscience.co.uk/atomicstructure1.htm
Arrangement
of electrons
•Electrons are in energy levels
within an electron cloud.
Around the nucleus
•1st energy level can hold
•2nd energy level can hold
•3rd energy level can hold
•4th energy level can hold
2 e8 e8 e18 e-
Each orbital can contain 2 electrons
Electron
Configuration
•Arrangement of electrons in
orbitals
•Most stable in the lowest
possible energy level
•If all electrons have the lowest
possible energies, the atom is in
ground state
•Ex. Magnesium
Symbol  Mg
Atomic Number  12
# of p+  12
# of e-  12
1st energy level  ____
2 (can hold 2)
2nd energy level  ____
8 (can hold 8)
3rd energy level  ____
2 (can hold 8)
Magnesium
12
p+
•Ex. Aluminum
Symbol  Al
Atomic Number  13
# of p+  13
# of e-  13
1st energy level  ____
2 (can hold 2)
2nd energy level  ____
8 (can hold 8)
3rd energy level  ____
3 (can hold 8)
Aluminum
13
p+
•Ex. Fluorine
Symbol  F
Atomic Number  9
# of p+  9
# of e-  9
1st energy level  ____
2 (can hold 2)
2nd energy level  ____
7 (can hold 8)
3rd energy level  ____
none (can hold 8)
Fluorine
9 p+
Practice
Determine the # of e- in the following
elements. Draw their electron configuration.
Lithium
Nickel
Oxygen
Sulfur
Helium
Argon
Titanium
Carbon
Beryllium
Zinc
Preparing for tomorrow
 Tomorrow you will be having a lab where
you concentrate on Atomic Structure
 Make a list of supplies that you will need
in order to make a model of any atom of
your choosing beyond element #10
Oxygen
 Bring your supplies to class or drop them
by room 604 tomorrow morning
Lab
 This lab you will be creating a Bohr Model of
any atom that you choose beyond Oxygen
 You must bring your own supplies for this
 EX: cookies with icing to hold the P+ N0 and
E- in place
 Make a key that show the atomic name,
number, symbol and atomic mass number
After you complete your
model…
 Once you have completed your model
you are to have your teacher check you
off. You will need to have your key and
be able to answer questions about your
model ie.. How did you determine the
number of protons, neutrons electrons
etc.