Do Now
• Describe the structure of the atom…
• You must include….
• The names of the subatomic particles.
• Their charges.
• Where in the atom they are located.
Atomic Structure
• Protons- Positively charged particles located in the
nucleus
• Neutrons- Uncharged particles located inside the
nucleus
• Electrons- Negatively charged particles located
outside the nucleus
Comparing subatomic particles…
particle
symbol
electron
e-
relative
mass
(amu)
1/1840
proton
p+
1
neutron
n0
1
Green – metals
Yellow – nonmetals
Blue - metalloids
Atomic Number
• # of protons
• # of electrons in a NEUTRAL atom
• Always a whole number
Mass Number
• # of protons + neutrons
• in atomic mass units (amu)
• Isotopes - atoms of the same element with
different masses
• differ in number of neutrons
• Examples: Carbon-13 & Carbon-14
Do Now
• Draw Lewis dot structures for Nitrogen, Calcium,
Sulfur, and Potassium.
• Give the oxidation numbers for Sodium, Iodine,
Phosphorus, Barium, Aluminum, and Oxygen.
• Give the formula for the compound formed
between Magnesium and Nitrogen.
Oxidation Number
• - The charge that the ion gets when it either loses
or gains electrons is called the oxidation number.
The sum of the oxidation numbers for the atoms in
a compound must be zero
In order for a compound to exist, it must
be electrically neutral
‘Criss - Cross’ Method
The formula for the The formula for the
compound composed
compound composed
of potassium and
of calcium and
sulphur
bromine
K 1+ & S 2-
This becomes K2S
Ca 2+ & Br 1-
This becomes CaBr2
Steps to follow
• Step 1- write element symbols with the metal first
• Step 2- write the oxidation numbers next to the
elements
• Metals = valence electron number (with a (+) sign)
• Nonmetals = -(8-valence electron #)
• Step 3- criss-cross numbers without signs
• Step 4- don’t write 1’s for final compound
• Step 5- Reduce the numbers
Welcome Back!!!
Do Now
Group
Period
2
4
17
5
13
4
6
6
Element
Name
Element
Symbol
P (+)
N (0)
E (-)
Do now
• Q2Z is the formula of an ionic compound made
from non-existant elements.
• Which element is a non metal?
• What are the oxidation numbers for each element?
• How many valance electrons does each element
have?
• Draw a dot structure for each element.
Counting Atoms in a Compound
• Subscripts- small number next to an element
• Example: Al₂ O₃
1 compound: Al₂O₃
2 elements: Al and O
5 atoms : 2 aluminum and 3 oxygen atoms
Compounds with parentheses
• Multiply the number outside the parentheses by all
of the subscripts inside
• Example:
• Ga₂ (SO₄)₃
• Ga = 2 , S = 1x3 = 3 , O = 4x3 = 12
Find the number of atoms for each
element in the following compounds:
• AgNO3
•
• Al(ClO3)3
•
• (NH4)2SO3
DO NOW
• What is the difference between a physical change
and a chemical change?
Chemical Reaction
• A reaction happens when two or more molecules
interact and the molecules change.
• A chemical change must occur. You start with one
compound and turn it into another.
Chemical Equations
• Their Job: Depict the kind of reactants and
products and their relative amounts in a
reaction.
4 Al (s) + 3 O2 (g) ---> 2 Al2O3 (s)
• The numbers in the front are called
coefficients
Chemical Equations
• All chemical equations have reactants and products.
• We express a chemical equation as follows:
Reactants  Products
• The arrow is equivalent to an “=“ math. When we
describe the equation we use the word “yields” or
“produces” instead of equals
• Example
C + O2  CO2
• This reads “carbon plus oxygen react to yield carbon dioxide”
Chemical Equations
A. _______________
B. _______________
C. _______________
D. _____________
E. _____________
F. _____________
Subscripts vs. Coefficients
• The subscripts tell
you how many
atoms of a
particular element
are in a compound.
The coefficient tells
you about the
quantity, or
number, of
molecules of the
compound.
2Mg + O₂  2MgO
What are the reactants in the equation above?
• Mg and O
• What are the products in the equation above?
• MgO
•2
Do now
• Explain why coefficients are needed in a chemical
equation.
Balancing Chemical Equations
Because of the law of the conservation of
matter (matter can not be created or
destroyed) an equation must be balanced.
It must have the same number of atoms of the
same kind on both sides.
Balance this equation!
Na + Cl2
Na-1
Cl-2
NaCl
Na-1
Cl-1
**note that the number of sodium atoms balance
but the chlorine does not. We will have to use
coefficients in order to balance this equation.
Do Now
• Balance this equation
• ____ N2 + ____ F2  ____ NF3
Try this one
• ____ Na3PO4 + ____ KOH  ____ NaOH + ____ K3PO4
Do Now
• Describe some pieces of evidence that would
indicate a chemical reaction has taken place.
Types of Reactions: Single Replacement
A + BC
Zn + 2HCl
2Al + 3CuCl2
B + AC
H2 + ZnCl2
3Cu + 2AlCl3
Types of Reactions: Double Replacement
AB + CD
Ag(NO3) + NaCl
2Ag(NO3) + K2(CrO4)
AD + CB
AgCl + Na(NO3)
Ag2(CrO4) + 2K(NO3)
Types of Reactions: Decomposition
AB
C12H22O11
A + B
12C + 11H2O
Types of Reactions: Synthesis
A+B
2Mg + O2
AB
2 MgO
Endothermic/exothermic Reactions
• A reaction that releases heat as it happens is called
Exothermic.
• A reaction that absorbs heat is called Endothermic.
• An Endothermic reaction feels cold (because it is
absorbing your heat)
• An Exothermic reaction feels hot. (because it is
giving off heat)
Exit Card: Name Each Reaction
DO NOW
• Define an endothermic and exothermic reaction
• A reaction that absorbs heat is called endothermic.
• A reaction that releases heat is called exothermic.
• An Endothermic reaction feels cold (because it is
absorbing your heat)
• An Exothermic reaction feels hot. (because it is
giving off heat)
Do Now:
• Describe the difference between an ionic and a
covalent bond
Covalent Bonds
• A bond between two nonmetals.
• Electrons are shared instead of transferred to make
the compound stable.
ex: H + H  H2
Covalent Bonding
• Remember that ionic compounds transfer
electrons in order to attain a noble gas electron
configuration
Covalent compounds form by sharing
electrons to attain a noble gas electron
configuration
Regardless of the type of bond, the Octet Rule
still must be obeyed (8 valence electrons)
Single Covalent Bond
• A Single Covalent Bond consists of two atoms held
together by sharing 1 pair of electrons (2 e-)
Electron Dot Structure
Shared versus Unshared Electrons
• A Shared Pair is a pair of valence electrons that is
shared between atoms
An Unshared Pair is a pair of valence
electrons that is not shared between atoms
Double Covalent Bonds
Sometimes atoms attain noble gas
configuration by sharing 2 or 3 pairs of
electrons
• A Double Covalent Bond is a bond that involves 2
shared pairs of electrons (4 e-)
Triple Covalent Bond
• A Triple Covalent Bond is a bond that involves 3
shared pairs of electrons (6 e-)
Covalent Bonds
Do Now
• Define the rule of octet
• State how many bonds each atom can form
• Oxygen, Sulfur, Nitrogen, Carbon, Chlorine,
Phosphors, Hydrogen, Fluorine, (hint) draw dot
structures)
Naming Guidelines – PBr5
• Name of first element (phosphorus)
• Prefix needed if more than one atom
• Name of second element (Bromine)
• Prefix needed, even if 1 (mono)
• Root name plus –ide (pentabromide)
• PBr5 is phosphorus pentabromide
Possible Prefixes
•
•
•
•
•
•
•
•
•
•
One
Two
Three
Four
Five
Six
Seven
Eight
Nine
Ten
is
is
is
is
is
is
is
is
is
is
MonoDiTriTetraPentaHexaHeptaOctaNonaDeca-
Name Covalent Compounds
• CO
• CO2
• SO2
• SO4
• SF6
• NI3
• P2O5
• CCl4
Carbon monoxide
Carbon dioxide
Sulfur dioxide
Sulfur tetraoxide
Sulfur hexafluoride
Nitrogen triiodide
Diphosphorus pentoxide
Carbon tetrachloride