CHEMICAL BONDING
Chemical Bonds / Formulas
Atoms bond to become “happy” – octet rule
When they bond they form compounds.
Each compound has a special formula
Subscripts show how many of each element is in the compound
FORMULASMgCl2
The subscript is the number at the bottom of a formula.
There is 1- Mg & 2 – Cl Never use 1 as a subscript!
IONIC BONDformed between two ions by the transfer of electrons
Formation of Ions from Metals
Ionic compounds result when metals react with nonmetals
Metals lose electrons to form a positive charge
Nonmetals gain electrons to form a negative
charge
Metals: Nonmetals:
Na+ N -3
Ca+2 S -2
Al+2 Br -
IONIC BONDS Bonds form from the (+) & (-)
charges. Form a network of ions. Form
strong bonds. Conduct electricity when
melted or dissolved in water.
Writing Ionic Formulas – binary
Calcium & oxygen
Write the metal ion Ca +2
Write the nonmetal ion O -2
If charges cancel – ratio is 1:1 ( 1 of each)
CaO
Magnesium & chlorine
Write the metal ion Mg +2
Write the nonmetal ion Cl -
If charges DO NOT cancel – drop & swap
MgCl2
Transition Metals – d & f block Ion charges change – an element can have
more than one ion charge
The charge is given as a ROMAN NUMERALEx: Iron (II) Fe+2 / Iron (III) Fe+3
Gold (I) Au + / Gold (III) Au+3
You will not have to memorize all the charges each transition metal forms – the charges will be given to you !!!!!
Practice
Magnesium & iodine
Iron (III) & bromine
Barium & nitrogen
Aluminum & phosphorus
Naming Ionic Formula - binary
Representative MetalsName the metalChange the ending of
the nonmetal to – ide
Ex:MgCl2 - magnesium chloride
AlP - aluminum phosphide
Transition MetalsName the metal & Include the
charge using a Roman Numeral
Change the ending of the nonmetal ending to –ide
Ex:
Fe +2 Cl - iron (II) chloride
Au + O -2 gold (I) oxide
Practice CaBr2
Na3N
BCl3
MgO
FeCl3
Ni3N
ZnO
FeS
Ternary Ionic Bonds – contain Polyatomic Ions
Polyatomic ion : a group of (covalently) bonded nonmetals that form a charge.
Act as a single ion in an ionic bond
Have special names that DO NOT CHANGE
You need to write down the polyatomic ions and their names on an index card and DO NOT LOSE IT!!!
You will use your list on all quizzes and tests!
AmmoniumNH4+
Acetate C2H3O2-
Hypochlorite ClO-
Chlorite ClO2-
Chlorate ClO3-
PerchlorateClO4-
Cyanide CN-
Hydroxide OH-
Nitrite NO2-
Nitrate NO3-
Bicarbonate/Hydrogen Carbonate HCO3-
Carbonate CO3-2
Chromate CrO4-2
Dichromate Cr2O7-2
Oxalate C2O4-2
Sulfate SO4-2
Sulfite SO3-2
Phosphite PO3-3
Phosphate PO4-3
Permanganate MnO4-
Peroxide O2-2
Writing Ionic Formulas - ternary Write the cation – all metals (only polyatomic cation is
ammonium: NH4+ )
Write the anion – all nonmetals and polyatomic ions
If charges cancel – 1:1 ratio
If charges DO NOT cancel – drop & swap You must use parenthesis if more than one polyatomic
ion is present
Naming Ionic Formulas- ternary Cation
Representative metals- element nameTransition (D-block) metals- element name and a
Roman numeral to show chargePolyatomic ion (NH4
+)- regular name
AnionPolyatomic ion- regular nameNonmetal- change ending to -ide
Ex:NaNO3- sodium nitrate
Cu2(SO4)3- copper (III) sulfate
NH4Cl- ammonium chloride
Practice cesium nitrate
barium sulfite
aluminum hydroxide
strontium phosphate
ammonium sulfide
Iron(III) chlorite
Zinc(II) nitrite
Gold(III) carbonate
Silver(I) phosphite
Copper(I) acetate
COVALENT BONDbond formed by the sharing of electrons
Covalent Compounds
Covalent compounds result when nonmetals bond with nonmetals
Both nonmetals share their valence
electrons to be happy – Octet Rule
Examples:
CO2 SCl2
H2O CH4
Naming Covalent formulas Use prefixes to show the # of atoms of each
element in a covalent compound 1 – mono 6 - hexa 2 – di 7 - hepta 3 – tri 8- octa 4 – tetra 9 - nona 5 – penta 10 – deca
1st element – use prefixes only of the # of atoms is greater than 1
2nd element – use prefixes; change ending to – ide
Practice
CO2
N3F8
Se4Br9
S7O
tetraselenium nonabromide
trinitrogen octafluoride
heptasulfur monoxide
carbon dioxide
Writing Covalent formulas Use the prefix to identify how many of each
nonmetal atoms are in each molecule The prefix becomes the subscript.
Carbon Tetrahydride Disulfur Hexachloride○ CH4 S2Cl6
1) Name the following covalent compounds:a) SiF4
b) N2S3
c) H3Br7
d) S5Br9
e) H2O
2) Write the formulas for the following covalent compounds:
a) diboron hexahydrideb) nitrogen tribromidec) sulfur hexachlorided) diphosphorus pentoxide
Drawing Structures- Ionic Electrons are
TRANSFERRED
Practice: NaBr
AlCl3
Drawing Structures- Covalent Electrons are SHARED
1 pair= single bond2 pairs= double bond3 pairs= triple bond
Dot formulas and Structural formulas
Covalent Structure Practice H2O CH4
CO2 Cl2
O2 N2
Diatomic Molecules
Always pair up with themselves in a pure sample
Allows them to be stable when there are no other elements to bond with
H2, N2, O2, F2, Cl2, Br2, I2
Metallic Bonds Formed between two metals
One or two valence electrons (usually transition metals)
strong positive nuclei pull atoms close together, causing the outer e- orbitals to overlap
electrons delocalize; creates a ‘sea of electrons’○ electrons flow freely between atoms, this is why metals
are good conductors of electricity
The remaining slides are for
HONORS CHEMISTRY
only
VSEPR
Valence Shell Electron Pair RepulsionPredicts shapes of
covalently bonded molecules
Copy the chart on p.263 of your book
Coordinate Covalent Bonds one atom contributes both bonding
electrons once formed, no different from other
bonds, just different source of electrons
Coordinate Covalent Ex:Chlorate, ClO3
-
Resonance Structures
shifting of electron pairs/bonds without shifting atoms
Resonance Ex:Carbonate, CO3
-2
Ozone, O3