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Class:____________________
Unit 3 Chemistry Notes
Democritus
History and Experiments
Conclusions or Discoveries
-Comes from the time around __________ -Came up with the word _____________
-Ancient _________________ philosopher -He said that the atom was a small
-He performed ____________
__________________________ molecule
experiments during his time
-It was the ____________ piece of matter
Aristotle
-_______________________ B.C
-Stated that all matter was made up of
-___________________ Philosopher
__________________________________
-Used __________________ rather than
-Views were unchallenged for _________
experiments
years
John Dalton
-English school teacher who developed
1, All matter is made of _______________
the ________________________ in 1803 and indestructible atoms
-Studied the masses of _______________ 2. Atoms of the _______________
and ____________________ and their
element are identical
ratios
3. Atoms of _________________
-Used _______________________ data
elements are different
to support his theory
4. Atoms of different elements combine in
whole _______________________ and
form compounds
5. Chemical reactions consist of the
________________________________
__________________________ of atoms.
1. Law of conservation of mass
 Mass (matter) is neither created or destroyed, just rearranged.
 Mass of reactants = mass of products
J.J. Thompson
History and Experiments
Conclusions or Discoveries
-Researched the atom back
-Discovered ___________________
in___________
-Plum pudding model of the atom
-He used a
-(Chocolate Chip Cookie)
__________________________ and
observed the cathode ray is attracted to a
positive (+) charge
Observations
When using a magnetic field, the rays bent
away from the field
Inferences
When using electric fields the rays were
attracted to the (+) field.
When a small paddle wheel was placed in
the path of the cathode rays the wheel
was set in motion.
Ernest Rutherford
-Some of the most important discoveries
-Discovered the ____________________
related to the atom were completed by
-The nucleus is very _________________
Rutherford
______________
-His work was completed in__________
-The atom is mainly _______________
-________________________________
space
James Chadwick
Did work in __________
-Discovered the _________________, a
Theorized there must be a ____________ neutral subatomic particle with relatively
particle
the same mass as a proton.
-The masses of all atoms except
______________________ were known
to be greater than the combined masses
of their protons and electrons.
 ________________________– neutrally charged particle (no charge)
 ________________________ – made up of protons and neutrons
Niels Bohr
History and Experiments
Conclusion or Discoveries
-Bohr’s research on the atom was
-Electrons _____________________ the
completed in _______________________ nucleus
-Still highly relevant today
Draw Thompson’s Model
Draw Bohr’s model
Definitions
 ________________________ The smallest part of an element that upholds the
chemical properties of that element
 _________________________ A substance that can’t be broken down into
simpler chemical substances.
◦ What’s smaller: an atom or element?
Subatomic
Particle
Electron
Symbol
Charge
Location
Mass
Proton
Neutron
Periodic Table of Elements
-Just like the 26 letters of the alphabet combine to form all the words in the English
language, the 100 or so elements combine to form everything that exists in the world
-About 90 of the elements on the PT are found naturally in nature, the rest have been
created in a laboratory
-Any material made of one type of atom is classified as an ______________________
-The Periodic Table is organized into rows and columns
-Each vertical column is called a ____________________ or____________________
-Elements within the same group have similar properties EX. Au, Ag, Cu
-Each horizontal row is called a ____________________
-Properties of the elements gradually change when you move through a period
-Elements get smaller when you move from _________________ to ______________.
How to Read the Periodic Table
-Each element is designated by its _____________________________
-Some symbols do not match actual element name because they were named
under their ________________________________,
-The first letter of an atomic symbol is ____________________ and the second letter
is _______________________
-The atomic number is the special I.D. of the element
It can tell you how many _________________________ are in the element
-_____________________have an electric charge _____________
-Electrons are _____________________________________________ in an element
-_____________________ have an electric charge _____________
Atomic # = _______________________=________________________
-The atomic mass of an element is the number at the _______________of the square
-Atomic mass is the sum of the __________________________________ in the atom
-_____________________ have an electric charge ______________
Atomic mass = ______________________+_____________________
The _____________________ of an atom contains all the protons and neutrons
Element
35 Cl
17
7 Li
3
MASS #
ATOMIC #
#
PROTONS
#
NEUTRONS
#
ELECTRONS
Isotopes
-Atoms of the ________________________element that contain _________________
numbers of _______________________ are called Isotopes.
-We identify isotopes by their ___________________________. The mass number is
the total number of protons and neutrons it contains.
Mass # = _______________________ + ________________________
One way to express isotopes
Mass Number
OVER
Atomic Number
The total number of neutrons in an isotope is to subtract its atomic number from the
mass number.
Mass number
-Atomic Number
Number of Neutrons
Example
 How many Protons?
 How many Neutrons?
 How many Protons?
 How many Neutrons?
Atomic mass is the ___________________________________ of an element and its
various isotopes.
Measured in ______________________________________ (amu)
Example: Imagine 100 students take a test worth 100 points. If all students scored an
80 then the average would be an 80%. But what would happen if one student gets a
100%? It would raise the average slightly.
Same thing happens with isotopes
Element X has 45 protons and 50 neutrons, while Element Y has 50 protons and 45
neutrons
Same, Different, Isotope?
Element A has 13 protons and 15 neutrons, while Element B has 13 protons and 14
neutrons
Same, Different, Isotope?
Electromagnetic Spectrum
All types of electromagnetic radiation share common characteristics:
◦ ____________________________
 c - Speed of light (in a vacuum) = 3.0 x 108 m/s constant
 λ – ___________________________
 ν - ____________________________
_____________________________________-set of frequencies of the
electromagnetic wave emitted by atoms of the element.
Each element is unique.
Flame gives off colors
Quantum Model
The ____________________________ describes the probability of finding an electron
in a given region of space called an _________________________.
n = __________________________________
Major energy levels
Larger n, the further away electron is from nucleus and the higher its energy
Values of n are whole numbers from 1  infinity
l = _____________________________________
Designates the shape of the orbital
Values of l are whole numbers from
l = 0 to n – 1
N=2
L= 0 n-1
L=0,1
L Value
Letter
Shape
Ml= _____________________________________
Designates the orientation of the orbital in space
Values of m are whole numbers:
-l  0  +l
For example, if l = 1 calculate m
Therefore, m = -1, 0, +1
Ms=_____________________________________
Describes the direction of an electron’s spin
Electrons spin on their axis either clockwise or counterclockwise
Only two possible values: +1/2 or -1/2
Quantum numbers (n, l, ml, and ms) attempt to locate where electrons in an atom
“should” be
Quantum numbers are analogous to the information give on a ticket stub: Stadium,
Section, Row, and Seat
 n=4
 l=
 ml=
 ms=
 n=2
 l=
 ml=
 ms=
 n=1
 l=
 ml=
 ms=
Electron Configuration and Orbital Notation
We identify elements based on how the _____________ are arranged in __________.
At least ____________shells and each shell can hold a certain amount of electrons.
Draw the amount of electrons allowed in each shell
Electron Configuration
 For full configuration you must have all prior parts as well!
2
2
5
 Fluorine: 1s 2s 2p
 All adds up to 9!
 Francium
2
2
6
2
6
2
10
6
2
10
6
2
14
10
6
1
 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s
 All adds up to 87!
 The block method!
 Fill in the blocks
Quick Review
1. What Element?
What Period?
Final part of configuration?
2. What Element?
What Period?
Final part of configuration?
_______________________________ is a way to show how many electrons are in an
orbital for a given element. They can be shown with arrows.
Take what we just learned with electron configuration but take it a step further.
Each line can hold up to _________ electrons.
◦
◦
◦
◦
S= ____
P= ____ ____ ____
D= ____ ____ ____ ____ ____
F=____ ____ ____ ____ ____ ____ ____
________________________________Principal
A max. of two electrons can occupy each orbital and these electrons must have
opposite spin
________________________________ Principal
Electrons will occupy the lowest energy levels possible
________________________________Rule
Electrons enter orbital's of the same energy one at a time before pairing up
◦ It is more STABLE to have the max. number of unpaired electrons
Mole Conversions
23
1 mole of any substance has 6.02 x 10 atoms
Avogadro’s number
1 mole of any substance is equal to its mass on the periodic table in grams.
Molar mass
How many atoms is 2.5 moles of Copper?
How many grams is 2.22 x 1025 atoms of Zinc?
Lewis Dot Structure
 Depending on what group they are in on the periodic table determines how many valence
electrons they have.
 You cannot double up valence electrons until each side of the element has an electron
Try creating Lewis Dot structures for the first 10 elements!
H
He
C
N
Li
O
Be
F
B
Ne
Additional Notes
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