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ChemIH: Chapter 8 Covalent Bonding (click for video)
Def: bonds btwn 2 or more nonmetals
Nonmetals have high EN values so electrons must be shared
Compounds w/covalent bonds are called molecular compounds.
We will learn about 4 types of molecular cpds.
1. Acids
• Acids are covalent compounds that act like ionic compounds.
• They have H+ as the “cation”.
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Acids
• There are 3 types of acids.
• They are named based on the type of ANION they contain:
1.Anion = element
2.Anion = polyatomic ion that ends in “ate”
3.Anion = polyatomic ion that ends in “ite”
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Acids
1. If anion is an element, name of acid is “hydro____ic acid” where blank is filled with root of element name
• Ex: HCl
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Hydrochloric acid
Acids
2. If anion is a polyatomic ion that ends in
“-ate”, name of acid is “____ic acid” where blank is filled with root of polyatomic ion name
• Ex: HClO3
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chloric acidClO3 = “chlorate”
Acids
3. If anion is a polyatomic ion that ends in
“-ite”, name of acid is “____ous acid” where blank is filled with root of element name
• Ex: HClO2
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chlorous acidClO2 = “chlorite”
Acids, Summary
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Type of Anion
Naming rule Example
Element Hydro___ic acid HCl: hydrochloric acid
Polyatomic “-ate”
____ic acid HClO4: perchloric acid
Polyatomic “-ite”
____ous acid HClO: hypochlorous acid
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Covalent Bonding
• By sharing e-s, atoms obtain NGC, which makes them more stable than they were by themselves.
H + H H : H = HH = H2
hydrogen molecule
Covalent Bonding
• single bond shares 1 pair electrons- ex:H2
• double bond shares 2 pairs electron-ex:O2
• triple bond shares 3 pairs electrons-ex: N2
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Learning Check(DON’T COPY)
Indicate whether a bond between the following would be
(I) Ionic OR (C) covalent
____ A. sodium & oxygen
____ B. nitrogen & oxygen
____ C. phosphorus & chlorine
____ D. calcium & sulfur
____E. chlorine & bromine
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Solution(DON’T COPY)
Indicate whether a bond between the following would be
(I) Ionic OR (C) covalent
I A. sodium and oxygen
C B. nitrogen and oxygen
C C. phosphorus and chlorine
I D. calcium and sulfur
C E. chlorine and bromine
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2. Diatomic Elements
• Elements that exist as atom pairs
• H2, O2, N2, Cl2, Br2, I2, F2,
• They are given the name of the element.
octets
N +
N N:::N triple bond
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Learning Check(DON’T COPY)
Use the name of the element to name a
diatomic molecules.
H2 hydrogen
N2 nitrogen
Cl2 _______________
O2 _______________
I2 _______________
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Solution(COPY)
Use the name of the element to name the
following diatomic molecules.
H2 hydrogen
N2 nitrogen
Cl2 chlorine
O2 oxygen
I2 iodine
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3. Binary Covalent CompoundsTwo nonmetals (def of binary covalent)1.Name each element 2.End the last element in -ide3.Add prefixes to show how many atoms of each
(except when there’s only 1 atom of the 1st element listed)
PREFIXES-COPY ONTO YOUR P. TABLEmono 1 hexa 6di 2 hepta 7tri 3 octa 8tetra 4 nona 9penta 5 deca 10
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Learning Check(DON’T COPY)
Fill in the blanks to complete the following names of covalent compounds.
CO carbon ______oxide
CO2 carbon _______________
PCl3 phosphorus _______chloride
CCl4 carbon ________chloride
N2O _____nitrogen _____oxide
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Solution(COPY!)
CO carbon monoxide
CO2 carbon dioxide
PCl3 phosphorus trichloride
CCl4 carbon tetrachloride
N2O dinitrogen monoxide
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Learning Check(DON’T COPY)
A. P2O5 1) phosphorus oxide2) phosphorus pentoxide3) diphosphorus pentoxide
B. Cl2O7 1) dichlorine heptoxide2) dichlorine oxide3) chlorine heptoxide
C. Cl2 1) chlorine2) dichlorine3) dichloride
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Solution(DON’T COPY)
A. P2O5 3) diphosphorus pentoxide
B. Cl2O7 1) dichlorine heptoxide
C. Cl2 1) chlorine
4. Hydrocarbons-A Type of Binary Covalent Compound
• Def: hydrocarbons are made of hydrogen & carbon
• They are named by the number of carbon atoms a molecule contains.
• They are important as fuels.
Hydrocarbons • The table below lists only hydrocarbons w/single
bonds• The names all end w/ “ane”
(COPY ONTO YOUR P. TABLE)
CH4 methane C6H14 hexane
C2H6 ethane C7H16 heptane
C3H8 propane C8H18 octane
C4H10 butane C9H20 nonane
C5H12 pentane C10H22 decane
Writing Formulas for Molecular Compounds
1. Analyze the name of the compound
2. Identify the type of compound (diatomic? binary? hydrocarbon?)
3. Reverse the process used to name it so you can determine the formula.
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Tips for Identifying TYPE of Molecular Compound
IF THE NAME HAS: TYPE OF COMPOUND HOW TO WRITE
FORMULA
• Just the name of 1of • Diatomic Element • H2, O2, N2, Cl2,
the following elements: Br2, I2, F2
(HONClBrIF)
• Prefixes • Binary (2 elements) • Turn prefixes into
• Ends in “-ide” subscripts. (Write them after element symbol)
• Ends in “-ane” • Hydrocarbon • Look it up on list of hydrocarbons!LecturePLUS Timberlake 23
Common v. Formal Names
• Formal Names follow the rules we have learned for naming compounds.
• Common Names are ones that don’t follow these rules.
–Ex: water=
Frequently Used Common Names
• Water = H2O
• Ammonia = NH3
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Covalent Bonds in NH3
(DON’T COPY)
Bonding pairs
H
H : N : H
Lone pair of electrons
Allotropes• Def: molecules of the same element that differ in
structure
• Ex 1: Carbon…graphite, charcoal, Buckminsterfullerine (“bucky ball”)=
C64
• Ex 2: O2 (oxygen) and O3 (ozone)
Q:Why do we have to specify the number of atoms of each element in
a covalent compound? (DON’T COPY)
A: Atoms of the same elements can combine in different ratios.
• Ex: C & OCOCO2
Writing Formulas for Covalent Compounds
1. Identify it as a covalent: containing only nonmetals.
2. Determine what type of covalent it is:
• diatomic element
• binary
• hydrocarbon (ends in –ane)
• acid/base
3. Reverse the naming process. LecturePLUS Timberlake 29
STOP HERE!!!
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PLEASE NOTE:• IF YOU ARE UNABLE TO
IDENTIFY IONIC & COVALENT COMPOUNDS, YOU WILL BE LOST!!!
• PLEASE SEE ME IMMEDIATELY TO GET CAUGHT UP.
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Naming Binary Ionic Compounds
1. Name the cation, which is the given the name of the element.
2. Name the anion, which is given the name of the element, w/the ending changed to “–ide.”
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PRACTICE Naming Binary Ionic Compounds
1. Na║Cl
2. Na = “sodium”
3. Cl = “chloride”(full name is “sodium chloride”)
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PRACTICE Naming Binary Ionic Compounds
1. Li2O
2 & 3.
____║____= ______ ______ (cation (anion (cation name) (anion name)
symbol) symbol)
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Learning Check
Match each set with the correct name:
A. Na2CO3 1) magnesium sulfite
MgSO3 2) magnesium sulfate
MgSO4 3) sodium carbonate
B. Ca(HCO3)2 1) calcium carbonate
CaCO3 2) calcium phosphate
Ca3(PO4)2 3) calcium bicarbonate
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Solution
A. Na2CO3 3) sodium carbonate
MgSO3 1) magnesium sulfite
MgSO4 2) magnesium sulfate
B. Ca(HCO3)2 3) calcium bicarbonate
CaCO3 1) calcium carbonate
Ca3(PO4)2 2) calcium phosphate
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Learning Check
A. aluminum nitrate
1) AlNO3 2) Al(NO)3 3) Al(NO3)3
B. copper(II) nitrate
1) CuNO3 2) Cu(NO3)23) Cu2(NO3)
C. Iron (III) hydroxide
1) FeOH 2) Fe3OH 3) Fe(OH)3
D. Tin(IV) hydroxide
1) Sn(OH)4 2) Sn(OH)2 3) Sn4(OH)
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Solution
A. aluminum nitrate
3) Al(NO3)3
B. copper(II) nitrate
2) Cu(NO3)2
C. Iron (III) hydroxide
3) Fe(OH)3
D. Tin(IV) hydroxide
1) Sn(OH)4