Covalent BondsCovalent Bonds

Chapter 1 Section 3Chapter 1 Section 3

BackgrouBackgroundnd• IonicIonic bonds usually form bonds usually form

between a metal and a nonmetal. between a metal and a nonmetal. •But when 2 But when 2 nonmetalsnonmetals bond, a bond, a

lot of energy is needed to either lot of energy is needed to either gain or lose an electron.gain or lose an electron.

• Instead of using energy, atoms of Instead of using energy, atoms of nonmetals will nonmetals will SHARESHARE their their electrons in order to bond.electrons in order to bond.

Covalent BondsCovalent Bonds•Covalent BondCovalent Bond

– forms when 2 – forms when 2 or more or more nonmetalnonmetal atoms atoms share electrons.share electrons.

•By sharing, By sharing, each atom has each atom has a full a full outer outer energyenergy level. level.

Here is anHere is ananimationanimation

showing sharing showing sharing electrons.electrons.

•When two or more atoms are When two or more atoms are joined in a covalent bond, joined in a covalent bond, they make a they make a MoleculeMolecule..

•Examples:Examples:–A A hydrogen molecule is is composed of 2 covalently composed of 2 covalently bonded H atoms.bonded H atoms.

–A A water moleculewater molecule is is composed of 1 oxygen composed of 1 oxygen and 2 hydrogen atoms and 2 hydrogen atoms bonded together.bonded together.

DiatomicDiatomic Molecules Molecules

•Often in nature, covalent Often in nature, covalent bonds occur between the bonds occur between the same elementsame element

•The following molecules are The following molecules are found in nature as diatomic found in nature as diatomic molecules:molecules:

•H O N Cl I Br FH O N Cl I Br F

Other Single Covalent Other Single Covalent Bonds – ClBonds – Cl22

• Or written:Or written:

Double Covalent Bond – Double Covalent Bond – two pairs of e- sharedtwo pairs of e- shared

Triple Covalent Bond – Triple Covalent Bond – three pairs of e- shared…three pairs of e- shared…

whoa.whoa.NN22

Making Covalent Bonds…Making Covalent Bonds…is funis fun

1.1. Draw Lewis Dot DiagramsDraw Lewis Dot Diagrams

2.2. Count # of unpaired electrons on eachCount # of unpaired electrons on each

3.3. Share unpaired electrons so all are Share unpaired electrons so all are happyhappy

4.4. Draw using dashes for bondsDraw using dashes for bonds

5.5. Write formulaWrite formula

6.6. Bathe in the success of completing a Bathe in the success of completing a covalent bond problemcovalent bond problem

Metallic BondingMetallic Bonding

• Bond formed by the attraction Bond formed by the attraction between between positivelypositively charged charged metal ions and the electrons metal ions and the electrons around them (the around them (the seasea of of electrons)electrons)

• Occurs in Occurs in metals metals …duh

Characteristics of MetalsCharacteristics of Metals

• ConductionConduction – electrons can flow easily – electrons can flow easily through them (conduct electricity)through them (conduct electricity)

• Ductility Ductility – ability to be made into – ability to be made into wireswires

• MalleabilityMalleability – ability to be hammered – ability to be hammered into sheetsinto sheets

• In general, metals may be reshaped or In general, metals may be reshaped or bent without breaking.bent without breaking.

M etal

M e ta llic B onds

M E T A LS

M o lecu les

C ova len t B onds

N O N M E T A LS

C rysta l La ttice

Ion ic B onds

Single, Double, and Single, Double, and Triple Covalent BondsTriple Covalent Bonds

Other Single Covalent Other Single Covalent Bonds – ClBonds – Cl22

• Or written:Or written:

Double Covalent Bond – Double Covalent Bond – two pairs of e- sharedtwo pairs of e- shared

Triple Covalent Bond – Triple Covalent Bond – three pairs of e- shared…three pairs of e- shared…

whoa.whoa.NN22

Naming Covalent Naming Covalent CompoundsCompounds

1.1. Element in “leftmost” column Element in “leftmost” column goes 1stgoes 1st

*If both elements are in same *If both elements are in same column, then lower atomic # goes column, then lower atomic # goes 1st1st

2. The 2nd element ends in -ide2. The 2nd element ends in -ide

3. Greek prefixes are used to show 3. Greek prefixes are used to show the number of each elementthe number of each element

Greek PrefixesNumber Prefix

1 mono-2 di-3 tri-4 tetra-5 penta-

** SEE PAGE 33 Exception: Mono- is usually dropped on the 1st element

ExamplesExamples

CClCCl44 = carbon = carbon tetratetrachloride chloride

PP22OO55 = diphosphorous = diphosphorous pentpentoxideoxide

CO = carbon CO = carbon monomonoxidexide

SOSO22 = sulfur = sulfur didioxideoxide

Some compounds have Some compounds have common names that were common names that were

made up before this system:made up before this system:•water - Hwater - H22O O

•ammonia - NHammonia - NH33

•methane - CHmethane - CH44

•ethane - Cethane - C22HH6 6

•propane - Cpropane - C33HH88