1. MR. CANOVA’S Science, Technology, & Society CLASS
CHEMISTRY REVIEW:
HISTORY OF THE ATOMIC MODEL
SUBATOMIC PARTICLES
IONIC AND MOLECULAR COMPOUNDS
NAMING AND WRITING FORMULAS
ACIDS

2. HISTORY OF THE ATOMIC MODEL

3. - no electric charge, electrically neutral
SCIENTIST MODEL
Democritus: The Greek Model (460 BC-370 BC)
Matter can’t be divided forever; there must be a smallest piece (atomos)
Atoms are indestructible, indivisible, & the fundamental units of matter
Atom: smallest particle of an element that retains the properties of that element.
- no electric charge, electrically neutral
No experiments to test his theories

4. SCIENTIST MODEL
John Dalton: Dalton’s Model ( )
Dalton’s Atomic Theory:
All elements are composed of atoms that are submicroscopic indivisible particles.
Atoms of the same elements are identical & atoms of different elements are different.
Atoms of different elements can physically mix together or chemically combine w/one another to form simple or whole-number ratios to form compounds.
Chemical reactions occur when atoms are separated, rearranged or joined. Atoms of one element can never be changed into atoms of another element.

5. J.J. Thomson: Thomson’s Model (1856-1940)
SCIENTIST MODEL
J.J. Thomson: Thomson’s Model ( )
Used cathode ray tube to discover electrons
Cathode ray: glowing beam which travels from
the cathode(-) to the anode(+).
- are composed of electrons
- are attracted to positive metal plate
Atoms had negatively charged particles
ELECTRON: negatively charged subatomic particle
“Plum Pudding” Model
(chocolate chip cookie) (watermelon with seeds)
-a ball of positive charge containing electrons

6. Thomson’s Model
POSITIVE CHARGE
ELECTRONS
EMBEDDED WITHIN

7. Cathode Ray Tube:

8. Robert Millikan Oil Drop Experiment (1916)
Determined the charge and mass of an electron
The mass is 1/1840 of the mass of a hydrogen atom (less than 1 amu)

9. NUCLEUS: center of the atom composed of PROTONS & NEUTRONS
SCIENTIST MODEL
E. Rutherford: Rutherford’s Model
Gold Foil Experiment
Discovered that most of atom’s mass is located in the positively charged nucleus
NUCLEUS: center of the atom composed of PROTONS & NEUTRONS
is 99.9% of the atom’s mass
a marble in a football stadium
Empty Space
++++++
+ Nucleus

10. Gold Foil Experiment: Rutherford

11. PROTON: positively charged subatomic particle
discovered by Eugen Goldstein ( )
put holes in cathode and saw rays traveling
in the opposite direction (canal rays)
NEUTRON: subatomic particle with no charge
discovered by Sir James Chadwick ( )
mass is nearly equal to proton (1 amu)
Thomson & Rutherford proved
Dalton’s Theory incorrect:
ATOMS ARE DIVISIBLE

12. Niels Bohr: The Bohr Model (1885-1962)
SCIENTIST MODEL
Niels Bohr: The Bohr Model ( )
Electrons move in definite orbits around the nucleus (planets around the sun)
PLANETARY MODEL
Electrons are a part of energy levels located certain distances from the nucleus
Electrons
++++++
Energy Levels

13. Energy Levels: region around the nucleus where the
electron is likely to be moving.
a ladder that isn’t equally spaced
further the distance, closer the spacing
the higher the energy level the farther it is from the nucleus
Electrons can jump from 1 energy level to another.
Quantum Energy: amount required to move an
electron from its present energy
level to the next higher one.

14. SCIENTIST MODEL
Erwin Schrodinger Quantum Mechanic Model
( )
Wave mechanics-mathematical
Probable location of electron
Cloud Shaped
Propeller blade
Subatomic particles: Electrons, Protons, & Neutrons
Atomic Number: Number of Protons in the nucleus
Whole number written above chemical symbol
Ex: Hydrogen=1(P) Oxygen=8(P)

15. SUBATOMIC PARTICLES

16. Subatomic particles: Electrons, Protons, & Neutrons
Atomic Number: Number of Protons in the nucleus
Whole number written above chemical symbol
Ex: Hydrogen=1(P) Oxygen=8(P)
Mass Number: Sum of Protons + Neutrons
Ex: Carbon Mass #12 = 6(P) + 6(N)
Oxygen Mass #16 = 8(P) + 8(N)
Mass # (#P + #N) - Atomic # (#P) = #Neutrons

17. LETS HAVE SOME PRACTICE
Atomic Number (P) 6 C
Carbon 12
Element Symbol
Element Name
Mass Number
(P+N)
Mass Number
(P+N) C 12 6
Atomic Number
(P)

18. WHAT GIVES AN ATOM ITS IDENTITY?
Isotope: Same # of Protons,
different # of Neutrons
Different Mass Number
Same Atomic Number
Chemically alike
Ex: Carbon-12 Mass #12 = 6(P) + 6(N)
Carbon-13 Mass #13 = 6(P) + 7(N)
Atomic Mass for isotopes of Carbon = amu

19. SO, WHAT GIVES AN ATOM ITS IDENTITY?
# of protons gives the atom its identity
# of electrons determines the chemistry of the atom
# of neutrons only changes the mass of the atom

20. HOW TO DETERMINE ELECTRON CONFIGURATIONS
How electrons are arranged around the nuclei of atoms
3 RULES:
Aufbau’s
Electrons enter lowest energy level first
Pauli Exclusion Principle
Orbitals can hold 2 electrons of opposite spin
Hund’s
Electrons enter one orbital until parallel spins 20

21. Principle energy level (n)
Orbitals and Electron Capacity of the First Four Principle Energy Levels
Principle energy level (n)
Type of sublevel
# of orbitals per type
# of orbitals per level
(n2)
Maximum
# of electrons (2n2) 1 s 2 4 8 p 3 9 18 d 5 16 32 f 7 21

22. USING THE PERIODIC TABLE
Column #
NAME
Valence electrons
Ion Charge 1
Alkali Metals
Lose 1 +1 2
Alkaline Metals
Lose 2 +2
3 to 12
Transition Metals
Lose
VARIES 13
Boron group
Lose 3 +3 14
Carbon group
Lose/Gain 4
+/- 4 15
Nitrogen Group
Gain 3 -3 16
Oxygen Group
Gain 2 -2 17
Halogens
Gain 1 -1 18
Inert or Noble Gases
Stable 22

23. IONIC AND MOLECULAR COMPOUNDS

24. MOLECULAR VS. IONIC COMPOUNDS
MOLECULAR COMPOUNDS:
1. Low melting & boiling points
2. Solids, Liquids, and Gases at room temp.
3. Sharing of valence electrons
4. Two or more Nonmetallic elements
5. Contain covalent bonds
EX:
H2O CO2 CH4

25. MOLECULAR VS. IONIC COMPOUNDS
1. High melting & boiling points
2. Composed of ions (cation and anion)
3. Electrically neutral
4. Crystalline solids at room temperature
-coordination #, 3D patterns
5. Composed of a Metal and Nonmetal
6. Contains Electrostatic Bonds
EX:
NaCl MgCl2

26. How to Write an Ionic Formula:
1. Write down symbols
2. Determine Ionic Charges
3. Charges must cancel each other out
(equal zero)
if not, use criss-cross method to form subscripts to cancel out charges

27. EXAMPLES:
Potassium Bromide
K Br charges cancel KBr
Magnesium Oxide
Mg O-2 charges cancel MgO
Aluminum Nitride
Al N-3 charges cancel AlN
Magnesium Chloride
Mg Cl charges don’t cancel, criss-cross MgCl2
Sodium Sulfide
Na S charges don’t cancel, criss-cross Na2S
Aluminum Oxide
Al O charges don’t cancel, criss-cross Al2O3

28. Naming an Ionic Formula:
1. Write the name for the metal and nonmetal
2. Check to see if the metal has more than
one charge (Cu, Fe, transition metals)
3. If metal has more than one charge, you
must do a “reverse” criss-cross to
determine formula
A Roman Numeral goes between the two names
4. Change the nonmetal ending to IDE

29. KBr potassium bromide Na2O sodium oxide MgS magnesium sulfide
EXAMPLES:
KBr potassium bromide
Na2O sodium oxide
MgS magnesium sulfide
Cu Br copper II bromide
As O arsenic V oxide
Fe2 O3 iron III oxide

30. How to Name a Molecular Formula:
Ex: CO CO2
1. Element with the (+) apparent charge comes 1st
carbon carbon
2. Second element ends in IDE
carbon oxide carbon oxide
3. Use prefixes to distinguish between compounds & to show how many atoms of each element are present
carbon monoxide carbon dioxide

31. Prefixes for Molecular Compounds:1
mono
Don’t use for first named element 2 di
Ex: CO 3
tri
carbon monoxide 4
tetra 5
penta 6
hexa 7
hepta 8
octa 9
nona 10
deca
1. drop vowel on prefix if element starts with vowel
EX: monooxide =
monoxide
2. Don’t drop vowel for
di and tri prefixes

32. phosphorus pentachloride
EXAMPLES: NO
NO2
N2O
N2O3
PCl5
CS2
SF6
nitrogen monoxide
nitrogen dioxide
dinitrogen monoxide
dinitrogen trioxide
phosphorus pentachloride
carbon disulfide
sulfur hexafluoride

33. How to Write a Molecular Formula:
Write down element symbol
Prefixes give you what subscripts to use

34. phosphorus pentachloride
EXAMPLES: NO
NO2
N2O
N2O3
PCl5
CS2
SF6
nitrogen monoxide
nitrogen dioxide
dinitrogen monoxide
dinitrogen trioxide
phosphorus pentachloride
carbon disulfide
sulfur hexafluoride

35. REMINDER WHEN WRITING FORMULAS:
CHECK YOUR HOLY SHEETS FOR ANY POLYATOMIC IONS
TREAT THEM AS EITHER A CATION OR AN ANION

36. There are two types of acids: 1. Binary acids-HCl(aq)
An ACID is a substance that when put into water, gives away a hydrogen ion (H+1) to another substance in the water solution.
HCl + H2O HCl(aq)
There are two types of acids:
1. Binary acids-HCl(aq)
2. Ternary acids-H2SO4(aq)
-polyatomic ions (ending in ate)
-polyatomic ions (ending in ite)