DO NOW:
1. Make a cover
page in your NB
for Chapter 5.
2. Draw a Bohr
diagram for
sulfur.
3. How many
valence
electrons does
sulfur have?
Chapter 5
Atoms and Bonding
Do Now: Draw a Bohr diagram for sulfur. How
many valence electrons does S have? Elements 1 - 20
Electron
Shell
Capacities:
16 P
16 N
Sulfur
• 16 electrons
• 6 valance electrons
1st level = 2
2nd level = 8
3rd level = 8
4th level = 2
Elements 21 – 112
1st level = 2
2nd level = 8
3rd level = 18*
4th level = 32*
5th level = 32*
*sub-levels exist
All atoms want to achieve a full octet; which
means they have a full outer valence shell
Neon
• 10 electrons
• 8 valence electrons
Ne
Why Do Valence Electrons Matter?
• The valence electrons show WHY certain
elements bond with other elements to form
compounds.
H
Sulfur’s 6
valence
electrons
WANT 2
more
electrons
H
S
2 Hydrogen
atoms will
make 8 total
Alkaline Earth Metals
Alkali Metals
Transition Metals
Halogens
Noble Gases
Oxygen Family
Nitrogen Family
Carbon Family
Boron Family
Remember, the # of valance electrons
matches its family #
*Matches 2nd digit groups 13 -18
Electron Dot Diagrams
AKA Lewis Structure
• Symbol of an element surrounded by “dots”.
• Each dot represents one valence electron.
Electron Dot Diagrams
AKA Lewis Structure
• The Element Symbol serves as the representation
of the nucleus.
Electron Dot Diagrams
AKA Lewis Structure
• Dots are added at 12 o’clock, 3 o’clock, 6 o’clock,
and 9 o’clock.
Carbon has only 4 electrons in the 2nd energy
level so we need only represent those 4
Electron Dot Diagrams
AKA Lewis Structure
• Only valence electrons are shown.
• Maximum of 8 dots (electrons)
Lewis Structure Practice
Oxygen
Group = 16
Valance electrons = 6
Chlorine
Group = 17
Valance electrons = 7
Draw Electron Dot Diagrams for
Beryllium and Sulfur
To Become Stable Atoms…
They Bond
Beryllium = Group 2
= 2 valance electrons
Sulfur = Group 16
= 6 valance electrons
Chemical Bonds
• Atoms with unfilled valence shells are considered
unstable.
• Atoms will try to fill their outer shells by bonding
with other atoms.
• The number of valence electrons will determine
how many bonds the atom can form.
• A chemical bond is the force that holds the
molecules together
• Two types of bonds we will discuss:
– Ionic bonds
– Covalent bonds
Chemical Bonds are represented with
Chemical Formulas
Understanding chemical formulas:
BaF2
Subscripts: tells how many atoms of that element are
in the compound
• refers only to the element preceding it
• The subscript 2 in this formula is for the F (fluorine)
• Ba (barium) only has one atom (1’s are not written)
Al(NO3)3
Parentheses: The subscript outside the parentheses
refers to all the elements inside the parentheses
• Multiply the subscript outside with each subscript
inside to get the total number of atoms
• In this example there are: one Al (aluminum),
three N (nitrogen), and nine O (oxygen) atoms
3BaF2
Coefficients: refers to each element that follows
• Multiply the coefficient with all subscripts
• The 3 in this example means there would be
3 Ba (barium) and 3 F2 (a total of 6 fluorine) atoms
Identifying and Counting Atoms
in a Chemical Formula
Try It: Count the Atoms in each Chemical Formula
Try It: Count the Atoms in each Chemical Formula
1
1
12
2
6
42
24
1
6
1
22
4
9
4
6
12
21
Back to Bonding…
Valence Electrons Determine
Oxidation Numbers
+1
+2
+4
+3 -4
0
-3
-2 -1
Oxidation Numbers
Shows the number of electrons an atom will
gain, lose, or share.
Positive (+) or negative (-) number assigned
to an element.
Comes from its family number on the Periodic
table
1)
2)
3)
4)
Metals (Families 1, 2, 13  +1, +2, +3)
Nonmetals (Families 15, 16, 17  -3, -2, -1)
Noble Gases (Family 18  0)
Transition metals have various oxidation numbers
between 1 and 4
0
+1
+2
+3
+4
-4
-3
-2 -1
Atoms that are no longer neutral are called ions
Ions:
• An atom or groups of atoms that have lost or
gained electrons
• Atom becomes either negatively (-) or
positively (+) charged
• Change occurs since the ratio of protons to
electrons is not equal
Ions form from atoms who gain or lose electrons
Cation: positive ion
• When an atom loses an electron
it becomes positively charged
• Ex: Calcium ion = Ca+2
Anion: negative ion
• When an atom gains an electron
it becomes negatively charged
• Ex: Fluorine ion = F–
(the 1 is inferred)
Oxygen at the Playground
Polyatomic Ions
• Ions that stay together
as a group
ammonium + nitrate
Poly- ionic name: ammonium nitrate
Polyatomic Ions
• Ions that stay together
as a group
ammonium + nitrate
Poly- ionic name: ammonium nitrate
Time to Bond Ions
• Each index card represents
either a cation (+) or an
anion (-)
• Any opposite charged ions can bond
• Writing the chemical formula and names:
1. Oxidation numbers will become subscript
numbers for the opposite element
2. Write both element names, but change the
second element ending to “ide”
Oxygen at the Playground
Ionic Bonding
How does it work?
• Ionic bonding takes place between metals and
non-metals.
• In an ionic bonds :
• oppositely charged ions (+) and (-) attract
• electrons are transferred
• Ex. NaCl (Na +1 Cl -1)
Naming Ionic Compounds
• Name of the + ion comes first, and - ion comes second
• Metal + Nonmetal
• Monatomic ions: change nonmetal ending to –ide
• Ex: Mg +2 + F -1 becomes
MgF2 or Magnesium Fluoride
• Polyatomic ions: change nonmetal ending to –ate
or –ite
Ex: NaNO3 = sodium nitrate
Mg3(PO4)2 = magnesium phosphate
Do Now
1. Draw the Lewis structure for:
• Magnesium +2
• Iodine -1
2. Write the chemical formula these two ions would create
• MgI2 (Magnesium Iodide)
3. What type of bond would these 2 atoms make?
• Ionic since Magnesium is Metal and Iodine is a Nonmetal
Covalent Bonding
• Occurs between two nonmetals
• Electrons are shared instead of being transferred
• Both atoms need to gain electrons, so they
share the electrons they have.
• Atoms still follow the octet rule
• No ionic charges or oxidation numbers
H O H
Sharing
electron
-
-
++ +
+ + +
+ +
-
+
Sharing
electron
-
-
-
-
+
How Covalent Bonding Works
• Electrons move back and forth between the outer
energy levels of each atom.
• Each atom has a stable outer energy level some
of the time.
• Atoms can share one, two, or three pairs of
electrons.
BrainPop Bonding
Bonding Animation
Carbon Dioxide (CO2)
Water
(H2O)
-
++ +
+ + +
+
+
- - -
++
+ +
+
+
- - -
+
++ +
+ +
+
+
-
-
Nitrogen
(N2)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
+
-
++
+
+ +
+
+
-
+
-
+
Single Bonds
Share 2
Electrons
-
Double Bonds
Share 4
Electrons
+
-
-
++
+ +
+
+
-
-
- - - -
-
+
++
+ +
+
+
-
Triple Bonds
Share 6
Electrons
Naming Covalent Compounds
1 mono
2 di
3 tri
4 tetra
5 penta
6 hexa
7 hepta
8 octa
9 nona
10 deca
• Each element gets a “greek prefix”
• Prefix refers to # of atoms in the
molecule
• Change ending to “ide”
• Ex: N2O4 = dinitrogen tetroxide
• The first vowel is often dropped to avoid
the combination of “ao” or “oo”.
octaoxide = octoxide
• Exception: drop mono for first element
CO2 = carbon dioxide
CO = carbon monoxide
NOW do you find this funny?!
Try This:
Name these covalent compounds:
CCl4
P2O3
IF7
•CCl4 = carbon tetrachloride
• P2O3 = diphosphorus trioxide
• IF7 = iodine heptafluoride
Try This:
Write the covalent compound formula:
• Tricarbon pentoxide
• Sulfur nonafluorine
• Tricarbon pentoxide = C3O5
• Sulfur nonafluorine = SF9
Candy Bonds Activity
Today’s Agenda
1. Candy Bonds activity
2. Discuss/Correct HW worksheets from last week:
•
•
Elemental Love Story
Naming practice
3. Complete Chapter 5 review worksheet
•
Check answers in back- flower folder
4. Share Answers to Candy Bonds
* If time: Draw Your Own- plain white paper
1. What type of bond occurs between a metal and a
nonmetal? ionic
2. What type of bond occurs between a two
nonmetals? Covalent
3. CaF2 Calcium fluoride (*ionic)
4. triphosphorus tetrabromide P3Br4
5. N5O9 Pentanitrogen nonoxide
Solutions:
Name these compounds:
• CCl4 = carbon tetrachloride
• P2O3 = diphosphorus trioxide
• IF7 = iodine heptafluoride
Write these compounds:
• Tricarbon pentoxide = C3O5
• Sulfur nonafluorine = SF9
What Kinds of Bonds are These?
Ionic Bonding
Sodium Chloride = NaCl = Na+1 + Cl-1