Chemical BondingPOPO44

3-3-

phosphate ionphosphate ion

CC22HH33OO22--

acetate ionacetate ion

HC2H3O2

Acetic Acid

Types of Chemical Types of Chemical BondsBonds

• There are 3 types of bonding There are 3 types of bonding atoms:atoms:

• IonicIonic—complete —complete transfer transfer of 1 or of 1 or more electrons from one atom to more electrons from one atom to another (one loses, the other another (one loses, the other gains)gains)

• CovalentCovalent——some valence some valence electrons electrons sharedshared between atoms between atoms

• __________________ – holds atoms of a – holds atoms of a metal togethermetal together

Most bonds are Most bonds are somewhere in somewhere in between ionic between ionic and covalent.and covalent.

Common NamesCommon Names• A lot of chemicals have common A lot of chemicals have common

names as well as the proper names as well as the proper IUPAC name.IUPAC name.

• Chemicals that should always be Chemicals that should always be named by common name and named by common name and never named by the IUPAC never named by the IUPAC method are:method are:

• HH22OO water, not dihydrogen water, not dihydrogen

monoxidemonoxide

• NHNH33 ammonia, not nitrogen ammonia, not nitrogen

trihydridetrihydride

CATIONCATION + + ANIONANION ---> --->

COMPOUNDCOMPOUND

CATIONCATION + + ANIONANION ---> --->

COMPOUNDCOMPOUND

A neutral compound A neutral compound requiresrequires

equal number of + equal number of + and - charges.and - charges.

A neutral compound A neutral compound requiresrequires

equal number of + equal number of + and - charges.and - charges.

COMPOUNDCOMPOUNDS FORMED S FORMED FROM IONSFROM IONS

COMPOUNDCOMPOUNDS FORMED S FORMED FROM IONSFROM IONS

NaNa++ + Cl + Cl- - --> NaCl--> NaCl

Predicting Charges on Monatomic IonsPredicting Charges on Monatomic IonsKNOW THESE !!!!KNOW THESE !!!!

+1 +2 +3 +/-4 -3 -2 -1 0

Cd+2

Properties of Ionic CompoundsProperties of Ionic CompoundsForming NaCl from Na and ClForming NaCl from Na and Cl22

Properties of Ionic CompoundsProperties of Ionic CompoundsForming NaCl from Na and ClForming NaCl from Na and Cl22

• A metal atom can A metal atom can transfer an electron transfer an electron to a nonmetal.to a nonmetal.

• The resulting cation The resulting cation and anion are and anion are attracted to each attracted to each other by other by electrostatic electrostatic forcesforces..

Ionic Bonds: One Big Greedy Thief Dog!

Formulas of Ionic CompoundsFormulas of Ionic Compounds

Formulas of ionic compounds are determined from the charges on the ions

atoms ions

–

Na + F : Na+ : F : NaF

sodium + fluorine sodium fluoride formula

Charge balance: 1+ 1- = 0

Monatomic IonsMonatomic Ions

Writing a FormulaWriting a Formula

Write the formula for the ionic compound that will form between Ba2+ and Cl.

Solution:

1. Balance charge with + and – ions

2. Write the positive ion of metal first, and the

negative ion Ba2+ Cl

Cl3. Write the number of ions needed as

subscripts BaCl2

Learning Check Learning Check

Write the correct formula for the compounds containing the following ions:

1. Na+, S2-

a) NaS b) Na2S c) NaS2

2. Al3+, Cl-

a) AlCl3 b) AlCl c) Al3Cl

3. Mg2+, N3-

a) MgN b) Mg2N3 c) Mg3N2

Solution Solution

1. Na+, S2-

b) Na2S

2. Al3+, Cl-

a) AlCl3

3. Mg2+, N3-

c) Mg3N2

Molecular (Covalent) Molecular (Covalent) CompoundsCompounds

CH4 methaneBCl3 boron trichloride

CO2 Carbon dioxide

All are formed from two or more nonmetals.

Ionic compounds generally involve a metal and nonmetal (NaCl)

COVALENT BONDCOVALENT BONDbond formed by the bond formed by the sharing sharing of electronsof electrons

Bonds in all the polyatomic ions

and diatomics are all covalent bonds

when electrons when electrons are shared are shared

equallyequally

NONPOLAR COVALENT BONDS

H2 or Cl2

2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons.

Oxygen AtomOxygen Atom Oxygen AtomOxygen Atom

Oxygen Molecule (OOxygen Molecule (O22))

when electrons when electrons are shared but are shared but

shared shared unequallyunequally

POLAR COVALENT BONDS

H2O

Polar Covalent Bonds: Unevenly matched, but willing to share.