Transcript Chemistry Review

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
HISTORY OF THE
ATOMIC MODEL
SCIENTIST
Democritus:
MODEL
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
SCIENTIST
MODEL
John Dalton:
Dalton’s Model
(1766-1844)
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 wholenumber 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.
SCIENTIST
MODEL
J.J. Thomson:
Thomson’s Model (1856-1940)
• 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
Thomson’s Model
POSITIVE
CHARGE
ELECTRONS
EMBEDDED
WITHIN
Cathode Ray Tube:
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)
SCIENTIST
E. Rutherford:
+++
+++
•
•
MODEL
Rutherford’s Model
Empty
Space
+ Nucleus
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
www.shsu.edu/%Echm_tgc/sounds/ruther.mov
Gold Foil Experiment:
Rutherford
PROTON: positively charged subatomic particle
discovered by Eugen Goldstein (1850-1930)
 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 (1891-1974)
 mass is nearly equal to proton (1 amu)
Thomson & Rutherford proved
Dalton’s Theory incorrect:
ATOMS ARE DIVISIBLE
http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/ruther14.swf
SCIENTIST
Niels Bohr:
MODEL
The Bohr Model (1885-1962)
Electrons
+++
+++



Energy
Levels
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

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.
SCIENTIST
Erwin Schrodinger
•
•
•
•
MODEL
Quantum Mechanic Model
(1887-1961)
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)
SUBATOMIC
PARTICLES
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
LETS HAVE SOME PRACTICE
Element
Symbol
Element
Name
Mass
Number
(P+N)
Atomic
Number
(P)
Atomic
Number
(P)
6
C
Carbon
12
12
6
Mass
Number
(P+N)
C
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 = 12.01 amu
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
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
Orbitals and Electron Capacity of the First Four Principle
Energy Levels
Principle
energy
level (n)
1
Type of
sublevel
# of
orbitals
per type
s
s
p
1
1
3
3
s
p
d
4
s
p
d
f
2
# of
orbitals
per level
(n2)
Maximum
# of
electrons
(2n2)
1
2
4
8
1
3
5
9
18
1
3
5
7
16
32
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
0
IONIC AND
MOLECULAR
COMPOUNDS
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:
H2 O
CO2
CH4
MOLECULAR VS. IONIC
COMPOUNDS
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
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
EXAMPLES:
Potassium Bromide
K+1
Br-1
charges cancel
KBr
Magnesium Oxide
Mg+2
O-2
charges cancel
MgO
Aluminum Nitride
Al+3
N-3
charges cancel
AlN
Magnesium Chloride
Mg+2
Cl-1
charges don’t cancel, criss-cross
MgCl2
Sodium Sulfide
Na+1
S-2
Na2S
charges don’t cancel, criss-cross
Aluminum Oxide
Al+3
O-2
charges don’t cancel, criss-cross
Al2O3
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
EXAMPLES:
KBr
potassium bromide
Na2O
sodium oxide
MgS
magnesium sulfide
Cu
As2
Fe2
Br2
O5
O3
copper II bromide
arsenic V oxide
iron III oxide
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
Prefixes for Molecular Compounds:
1. drop vowel on
prefix if element
starts with vowel
EX: monooxide =
monoxide
2. Don’t drop vowel
for
di and tri prefixes
1
mono Don’t use for first
named element
2
3
4
5
6
7
8
9
10
di
Ex: CO
tri
carbon monoxide
tetra
penta
hexa
hepta
octa
nona
deca
EXAMPLES:
NO
nitrogen monoxide
NO2 nitrogen dioxide
N2O
dinitrogen monoxide
N2O3 dinitrogen trioxide
PCl5
phosphorus pentachloride
CS2
carbon disulfide
SF6
sulfur hexafluoride
How to Write a Molecular Formula:
1. Write down element symbol
2. Prefixes give you what subscripts to use
EXAMPLES:
nitrogen monoxide
NO
nitrogen dioxide
NO2
dinitrogen monoxide
N2O
dinitrogen trioxide
N2O3
phosphorus pentachloride
PCl5
carbon disulfide
CS2
sulfur hexafluoride
SF6
REMINDER WHEN
WRITING FORMULAS:
CHECK YOUR HOLY SHEETS
FOR ANY POLYATOMIC IONS
TREAT THEM AS EITHER A
CATION OR AN ANION
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)