STAAR Chemistry Review
Topic: Bonding
TEKS 7 – The student knows how
atoms form ionic, covalent, and
metallic bonds. 7A - E
INDEX CARD TIME!
TITLE: Metals vs. Nonmetals
FRONT: create a GUIDE on how to determine if an
element is a metal or a nonmetal.
BACK: describe ionic, covalent and metallic bonds
in terms of which types of elements (metals or
nometals) are involved.
Metals vs. Nonmetals on the P. T.
3 types of bonds
• Ionic: between a METAL and a NONMETAL
– Electrons are TRANSFERRED from the metal to the
nonmetal
• Covalent: between NONMETALS
– Electrons are SHARED between the nonmetals
• Metallic: between METALS
– Electrons freely move around in a “SEA OF
ELECTRONS”
Student Expectation (SE)
7A – NAME ionic and covalent compounds using
International Union of Pure and Applied
Chemistry (IUPAC) nomenclature rules.
INDEX CARD TIME!
TITLE: Naming Ionic Compounds
FRONT: create a GUIDE on how to name ionic
compounds
BACK: provide at least 3 EXAMPLES of naming
ionic compounds
Ionic = METAL + NONMETAL
Mini-Review
• Cations – Positively charged ions (metals)
• Anions – Negatively charged ions
(nonmetals)
• Cations form by losing electrons
• Anions form by gaining electrons
• Charges for these ions are located at the
top of the columns on the periodic table.
(oxidation numbers)
Ionic: Naming
1.
Name the METAL (cation)
– group 1, group 2, silver, or zinc
• simply use the element’s name.
– Any other metal (transition metals):
• Use the element’s name and the charge in ROMAN
NUMERALS in parentheses.
2. Name the NONMETAL (anion)
– single element:
• use the element’s name with the –ide ending.
– Polyatomic ion:
• always use a polyatomic ion’s name unaltered.
• NO GREEK PREFIXES!
•
•
Ex: Na2O = Sodium oxide
Fe2(SO4)3 = Iron (III) sulfate
Examples
•
•
•
•
•
•
NaF: Sodium fluoride
KCl: Potassium chloride
Li2CO3: Lithium carbonate
Ca(NO3)2: Calcium nitrate
ZnSO4: Zinc sulfate
Cu(NO2)2: Copper (II) nitrite
INDEX CARD TIME!
TITLE: Naming Covalent Compounds
FRONT: create a GUIDE on how to name covalent
compounds
BACK: provide at least 3 EXAMPLES of naming
covalent compounds
Covalent= 2 NONMETALS
•
•
•
•
•
•
•
•
•
•
Mini-Review: Greek Prefixes
1
2
3
4
5
6
7
8
9
10
monoditritetrapentahexaheptaoctanonadeca-
Covalent: Naming
1. Name the 1st element.
-If there’s more than one, use a Greek Prefix.
2. Name the 2nd element.
-Always use a Greek Prefix with the 2nd element.
-change the ending to “–ide”
• Ex: PCl3 = Phosphorus trichloride
Examples
•
•
•
•
•
•
SO2: sulfur dioxide
SeF6: selenium hexafluoride
PCl5: phosphorus pentachloride
As2O5: diarsenic pentoxide
NO2: nitrogen dioxide
H2O: dihydrogen monoxide
Student Expectation (SE)
7B – write the chemical formulas of common
polyatomic ions, ionic compounds, and
covalent compounds.
INDEX CARD TIME!
TITLE: Writing Formulas for Ionic Compounds
FRONT: create a GUIDE on how to write formulas
for ionic compounds
BACK: provide at least 3 EXAMPLES.
Ionic = METAL + NONMETAL
Ionic: Writing Formulas
1. Write the SYMBOLS for the ions. (with oxidation
numbers)
2. Represent the oxidation number as a subscript on
the opposite ion!
3. Use parentheses around multiple polyatomic ions.
Ex: Magnesium Chloride = Mg+2 and Cl-1 -> MgCl2
Ex: Copper (II) sulfite = Cu+2 and (SO3)-2
Cu2(SO3)2 -> Cu(SO3)
Step 1 – Write chemical symbols of the
elements in a compound.
• Example: Calcium oxide
Ca
O
Step 2- Write the oxidation number for
each element as a superscript.
• Example: Calcium oxide
Ca2+
O2-
Step 3 – Criss-Cross superscripts to
subscripts.
• Example: Calcium oxide
Ca2+
O2-
Ca2
O2 = Ca2O2
Step 4 – Reduce Subscripts if needed.
• Example: Calcium oxide
2:2 ratio can be reduced to 1:1
CaO
Transition Metal Cations
• Because they have d-block electrons, transition
metals often can form multiple ions.
• It’s difficult to predict the charge on a transition
metal cation. These must be supplied to you.
• Ex. Naming: Fe2(SO4)3 = Iron (III) sulfate
• Ex. Formula: Copper (II) sulfite = Cu+2 and (SO3)-2
Roman
Oxidation
• Cu2(SO3)2 -> Cu(SO3)
These are on
the Back of
your Booklet!
Numeral
I
II
III
IV
Number
1+
2+
3+
4+
Examples
•
•
•
•
•
Aluminum bromide: AlBr3
Lead (II) sulfide: PbS
Magnesium chlorate: Mg(ClO3)2
Ammonium phosphate: (NH4)3PO4
Iron (III) nitrite: Fe(NO2)3
INDEX CARD TIME!
TITLE: Writing Formulas for Covalent Compounds
FRONT: create a GUIDE on how to write formulas
for covalent compounds
BACK: provide at least 3 EXAMPLES.
Covalent = 2 NONMETALS
Covalent: Writing Formulas
1. Write the SYMBOL for the 1st element.
-Write a SUBSCRIPT telling how many there
are according to the GREEK PREFIX.
2. Write the SYMBOL for the 2nd element.
-Write a SUBSCRIPT telling how many there
are according to the GREEK PREFIX.
Ex: Dinitrogen trioxide = N2O3
Examples
•
•
•
•
•
Diphosphorus pentoxide: P2O5
Carbon tetrabromide: CBr4
Silicon dioxide: SiO2
Diarsenic trisulfide: As2S3
Carbon monoxide: CO
Student Expectation (SE)
7C – construct electron dot formulas to illustrate
ionic and covalent bonds.
INDEX CARD TIME!
TITLE: IONIC electron dot structures
FRONT: Provide electron dot structures for one
metal and one nonmetal.
BACK: show the resulting TRANSFER of electrons
Ionic = METAL + NONMETAL
Mini Review
• The electron is physically TRANSFERRED from
a metal to a nonmetal.
Li
(Li+)
Picture used courtesy of http://www.ider.herts.ac.uk/school/courseware/materials/bonding.html
F
(F-)
= LiF
Electron Dot Structure
• The valence electrons are indicated by dots placed around
the element’s symbol.
• This can be used to represent up to eight valence electrons
for an atom. One dot is placed on each side before a
second dot is placed on any side. “empty corner rule”.
Octet Rule: atoms form bonds in order to get all 8 valence electrons.
IONIC LEWIS DOT STRUCTURES
• Not connected by bonds! But the transferred
electrons (and the new charges) are shown
.Al.
.
When ions pair, the total
positive charge must balance
out the total negative charge.
This means that ionic
compounds are electrically
NEUTRAL.
INDEX CARD TIME!
TITLE: COVALENT electron dot structures
FRONT: Provide electron dot structures for two
different nonmetals.
BACK: show the resulting SHARING of electrons
with a Lewis Dot Structure
Covalent = 2 NONMETALS
Mini Review: Covalent Bond
• The electron is SHARED between two
nonmetals. They are true molecules.
Cl
Picture used courtesy of http://www.ider.herts.ac.uk/school/courseware/materials/bonding.html
Cl
=Cl2
COVALENT LEWIS DOT STRUCTURES
• Single electrons
(not in pairs)
will form bonds
with other
single electrons
on different
atoms
Student Expectation (SE)
7D – describe the nature of metallic bonding
and apply the theory to explain metallic
properties such as thermal and electrical
conductively, malleability, and ductility.
INDEX CARD TIME!
TITLE: Metallic Bonds
FRONT: Describe the NATURE of a metallic bond
BACK: List some PROPERTIES of metallic bonds
Metallic = 2 or more METALS
Nature of Metallic Bonds
• Between METAL atoms.
• The valence electrons of metal atoms can drift
freely from one part of the metal to anotherthis is sometimes
called a “sea of electrons”
• Metallic bonds consist of
the attraction between these
free floating electrons and the
positively charged metal ions (cations). This
attraction is the “bond” that holds metals
together.
Properties of Metals
• Lusterous- they are shiny!
• High density- atoms are tightly packed.
• Good conductors of electricity and heat.
– Reason- electrons can flow freely.
Properties of Metals
• Ductile- they can be drawn into wires AND
• Malleable- they can be hammered into shapes
– Reason- cations can slide easily past each other
because the sea of electrons insulates them and
prevents strong repulsions.
Student Expectation (SE)
7E – predict molecular structure for molecules
with linear, trigonal planar, or tetrahedral
electron pair geometries using VSEPR.
INDEX CARD TIME!
TITLE: VSEPR
FRONT: Write down the theory of VSEPR
BACK: Describe how many bonding regions and
how many lone pairs surround the central atom
are needed for each VSEPR shape.
VSEPR is for
Covalent = 2
NONMETALS
Mini-Review
VSEPR: Valence-Shell Electron-Pair Repulsion
• -Used for COVALENT compounds ONLY).
• -Electron pairs form bonds between atoms
• But they’re still negative, and they still try to
repel each other.
• -Bonds and Lone Pairs try to get as far apart
from each other as possible.
• -Shape of the molecule is determined by the
number of bonding regions and lone pairs
around the central atom.
How to Determine VSEPR Shape
• 1. Draw the Lewis Dot Structure.
• 2. Count the # of bonding regions and # of
lone pairs on central atom.
– double/triple bonds = ONE bonding region
• 3. Determine SHAPE
Shape
(Angle)
# of Bonding
Regions
# of Lone
Pairs
Example
Linear
2
0
CO2
Bent
2
1
NO2-1
Bent
2
2
H2O
Trigonal
Planar
3
0
BF3
Trigonal
Pyramidal
3
1
NH3
Tetrahedral
4
0
CH4
Lewis Dot
Structure
VSEPR Shape
Drawing