ch 5 & 6: bonding, formulas and naming notes. types of chemical bonds: a. ionic bonding...
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Ch 5 & 6: Bonding, Formulas
and Naming
Notes
Types of Chemical Bonds:A. Ionic Bonding
1) Positively charged ions are attracted to negativelynegatively
charged ions, making a neutralneutral compound.2) Properties of Ionic Compounds:
a) high melting poinmelting pointsts. b) dissolve in water to form solutionssolutions that are
good conductorsconductors of electricity (electrolyteelectrolytess).
c) have a large electronegativityelectronegativity difference between elements.
d) usually form between metalsmetals and nonmetalsnonmetals.
3) The Octet Rule:
a) Atoms tend to gain or lose electrons in order to acquire a fullfull set of valencevalence electrons (stablestable octetoctet).
b) Atoms will transfertransfer electrons (e-) to each other in order to have a full set of valencevalence electrons.
c) When electrons are transferred, ionicionic bonds are formed.
Ions• Atoms can form ions by gaining or losing
electrons.– Metals tend to lose one or more electrons to form
positive ions called cations.
– Cations are generally named by using the name of the parent atom.
• Nonmetals tend to gain one or more electrons to form negative ions called anions.
Ions
• Anions are named by using the root of the atom name followed by the suffix –ide.
Ionic Bond Practice Tutorial
4) Types of Compounds:
a) Binary form from monatomic ions – have 1 cation and 1 anion.Ex) Mg+2 O-2
Ca+2 Cl-1MgO
CaCl2
Na +1Na +1
Na +1
O -2
O -2
+ 1 - 2 Not Balanced
2 + (- 2) = 0 Balanced Na2O
2 x +1 = +2 1 x -2 = -2
Al +3
O -2
Al +3
Al +3
O -2 O -2
O -2
+3 -2 Not Balanced
+ 6 + (- 6) = 0 Balanced Al2O3
2 x +3 = +6 3 x -2 = -6
4) Types of Compounds:
b) Tertiary form from polyatomic ions which consists of a group of atoms covalentlycovalently bonded with a singlesingle charge that bond ionically with other ions.Ex.
“ammonium sulfate” ,
NH4+1 SO4
-2
(NH4)2SO
4
Name this compound:
FeO
If that’s correct, name this:Fe2O3
How can we distinguish between these compounds?
What is the charge on the oxygen in each compound? Then what is the charge on the iron in each compound?
Fix the name of the first compound:
Iron oxide Iron (II) oxide
Iron (III) oxide
Fe+2 O-2
Fe+3 O-2
X
Ions
Ion Charges and the Periodic Table
5) Polyvalent Metals:
Some metals including the transitiontransition metals do not follow the octetoctet rule and may form more than 1 kind of cation. These ions are named with romanroman numeralsnumerals to distinguish between them.Ex) Fe+2 iron (II) read “iron two”
Fe+3 iron (III) read “iron three” FeCl2 iron (II) chloride
FeCl3 iron (III) chloride
Copper (I) sulfate Copper (II) phosphate
Cu2SO4
Cu3(PO4)2
6) Lewis Dot Diagrams for elements:
Element# of val. Electrons
Dot Diagram
Li 1 Li
N 5
Be 2
F 7
Ne 8
Au 2
C 4
Electron Dot Diagram for Atoms and Ions
7) Lewis-dot diagram for sodium chloride:
[Na+] [ -]
B. Covalent Bonding
1) Covalent Bonds are formed by sharingsharing pairs of
electrons between 2 atoms. 2) Usually formed between two nonmetalsnonmetals with
a lowlow electronegativity difference.3) Molecules:
a) a group of atoms held together by covalentcovalent
bondsb) molecular substance – contains moleculesmolecules
4) Naming: a) uses prefixes: 1 mono- 4 tetra- 7 hepta- 10
deca- 2 di- 5 penta- 8 octa-
3 tri- 6 hexa- 9 nona-
b) end in “ide”c) More electronegative element is written lastlastd) Only use a prefix on the first element if it is
more than oneone.e) Always use a prefix for the secondsecond elementelement.Ex) water H2O dihydrogen monoxidedihydrogen monoxide
smog NO2 nitrogen dioxidenitrogen dioxide
5) Types of formulas for covalent bondinga) Molecular Formula shows how manymany
atoms make up a compoundcompound.ex. CHCH44 & HH22OO
b) Structural Formula shows how the atoms are bondedbonded to each other.
ex.
1. Uses 2 dotsdots to show an unshared pair of
electronselectrons.2. Uses dashesdashes to represent covalent bonds (a
shared pair of electrons) in a structural formula.3. The octetoctet rule should be satisfied for each
element in the compound.c) Empirical Formula is the lowestlowest whole
number ratioratio of all the elements in the compound.
Ex) C6H6= CH
C6H12O6= CH2O
6) Multiple Bonds – can be used to satisfy the octet rule
Single Bonds – Share 11 pair of electrons.
Ex) methane or phosphorous trichloride
Double Bonds – Share 22 pairs of electrons.
Ex) formaldehyde, CH2O
Triple Bonds – Share 33 pairs of electrons (strongeststrongest bond).Ex) ethyne, C2H2
8) Properties of Covalent Bondsa) Low meltingmelting points, brittlebrittle, strong odorodor,
poor conductorsconductors of electricity.b) Polar Bonds – form between elements with
largelarge differences in electronegativity. These have an unevenuneven sharing of electrons.
Ex) water
partial negative side
partial positive side
c) Nonpolar bonds – exert equalequal pullpull on the electrons.
Ex) O2
9) Electronegativity Chart is used to determine bond type
non polar covalent polar covalent ionic bonds
0 0.4 1.9 4.0
even sharing - no charge
Ex) OO22
uneven sharing – slight charge on molecule
Ex) HH22OO
electrons transferred – forms ions
Ex) NaClNaCl
Types of BondsTypes of Bonds
C. Ionic & Covalent Bonds Summary:
Ionic Bonding Covalent Bondingmetal-nonmetal nonmetal-nonmetal
e- transferred e- shared
large electronegativity difference (>1.9)
electronegativity difference (0 1.9)
ions formed no ions
written cation (+) anion (-)more electronegative element written last
name cation - name anion use # prefixes/ends in ide
forms ionic compound (formula unit) in a crystal lattice
forms molecules
Written with a chemical or empirical formula
Written with a molecular or structural formula
NaCl – sodium chloride CCl4 – carbon tetrachloride
[Na+] [ -]
How Atoms Bond Video Clip
carbon tetrachloride
D. Acids:1) A molecular compound that
dissolves in water to produce H H ionsions and a characteristic anionanion.
2) In water, acids behave like ionicionic compounds.
3) Most acid formulas begin with HH. (Except organic acids) “ COOHCOOH”
4) The number of hydrogens in the formula depends upon the chargecharge of the anion.
5)Types of Acids
a.) Organic Acids contain the carboxyliccarboxylic group,
-COOH or
Ex) CHCH33COOH acetic acid COOH acetic acid (vinegar)(vinegar)
(or HC(or HC22HH33OO22))
b.) Binary Acids contain hydrogenhydrogen and 1 type of anionanion.A two-word name is used for binary acids.
1st word: prefix is “hydro”root is formed from the anionanion suffix “ide” is changed to “ic”
2nd word: is “acid”
Ex) HCl anion is chloride hydrochloric acidPrefix root suffix
HBr anion is bromide hydrobromic acidhydrobromic acid H3P anion phosphide hydrophosphoric hydrophosphoric
acidacid
c.) Oxo (Tertiary) Acids: contain oxygenoxygen within a polyatomic ion.A two-word name is used for oxo acids.
H2SO4 sulfate sulfuric acid
H2SO3 sulfite sulfurous acid
sulfur or phosphor (to sound better) 2nd word is “acid”If you “ate” something you don’t like, you
say “ic”“ite-ous”
HNO3 anion is nitrate nitric acid
root suffix
H3PO3 anion is phosphite phosphorous acid
Nitrous acid, anion is nitrite formula is: HNO2
Phosphoric acid, anion is phosphate
formula is: H3PO4
E. Hydrates:1.) Ionic compounds that absorb H2O into their
solid structures.Ex) magnesium sulfate heptahydratemagnesium sulfate heptahydrate (epsom
salt) Formula: MgSO4 7H2O
2.) Anhydrous substance – substance without substance without water water MgSOMgSO44
Ex) CuSO4 • 5H2O copper (II) sulfate pentahydratecopper (II) sulfate pentahydrate (bright blue)
CuSO4 – anhydrate (light blue/white)