CHEMICAL BONDSCHEMICAL BONDS

• How atoms combine to form different bonds

• How to predict what type of bond will form

TYPES OF BONDSTYPES OF BONDSElectrons are what cause atoms to “bond.”

Two main types of bonding• IONIC bonding: atoms transfer electrons • COVALENT bonding: atoms share

electrons

IONIC BONDSIONIC BONDS

• Held by +/- attraction

• Form ions (e- transfer) & conduct electricity

• OPPOSITE sides of Periodic Table

non-metal +

metal

IONIC BONDINGIONIC BONDING

PRACTICE: draw the formation of sodium chloride Step 1: Na + Cl Na + Cl Step 2: draw dots around the reactants Step 3: draw dots and charges around the products

sodium gives eleaving it with a full

valence orbital

chlorine gains e- leaving it with a full valence orbital

PREDICTING IONIC BONDINGPREDICTING IONIC BONDING

Opposite sides of PT (i.e. metal + non-metal)Opposite sides of PT (i.e. metal + non-metal)

Big difference in Electronegativity (Big difference in Electronegativity (≥ 1.8)≥ 1.8)

NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS

1.1. Name of 1Name of 1stst element (metal) element (metal)

2.2. Root of 2Root of 2ndnd element (nonmetal) element (nonmetal)

3.3. Root + “-ide”Root + “-ide”

LiFLiFlithium + fluorine lithium + fluorine lithium fluoridelithium fluoride

MgOMgOmagnesium + oxygen magnesium + oxygen magnesium oxidemagnesium oxide

COVALENT BONDSCOVALENT BONDS

• Held by sharing electrons(co=together valent=valence e-)

• Does NOT conduct electricity

• Usually same side of PT non-metal + non-metal

or metal + metal

Special type of covalent is metal to metal = metallic bond

COVALENT BONDINGCOVALENT BONDING

PREDICTING COVALENT BONDINGPREDICTING COVALENT BONDING

Same sides of PT (non-metal + non-metal)Same sides of PT (non-metal + non-metal)

Small difference in Electronegativity (Small difference in Electronegativity (< 1.8)< 1.8)

NAMING COVALENT COMPOUNDSNAMING COVALENT COMPOUNDS

1.1. Same as ionic (add –ide)Same as ionic (add –ide)

2.2. Add prefixes:Add prefixes: First WordFirst Word

• 1 = (understood)1 = (understood)• 2 = di2 = di• 3 = tri3 = tri• 4 = tetra4 = tetra• 5 = penta5 = penta• 6 = hexa6 = hexa

Second WordSecond Word• 1 = mono 1 = mono • 2 = di2 = di• 3 = tri3 = tri• 4 = tetra4 = tetra• 5 = penta5 = penta• 6 = hexa6 = hexa

PRACTICE NAMINGPRACTICE NAMING

COCOCarbon monoxideCarbon monoxide

COCO22

Carbon dioxideCarbon dioxide

SOSO22

sulfur dioxidesulfur dioxide

CClCCl44Carbon tetrachlorideCarbon tetrachloride

HH22OODihydrogen monoxideDihydrogen monoxide

SiSi55PP44 Pentasilicon tetraphosphidePentasilicon tetraphosphide

PREDICTING BONDS USING PREDICTING BONDS USING PT & ELECTRONEGATIVITYPT & ELECTRONEGATIVITY

How can you tell if a bond is ionic or covalent? Opposite or same sides of PT (covalent = SAME) ELECTRONEGATIVITY! (the ability to attract e-)

Electronegativity difference ≥1.8 = IONIC

< 1.8 = COVALENT

IONIC BOND COVALENT BOND

Bonding practice:

Na Cl

0.9 3.0

3.0

-.9

2.1 >1.8? Yes!

IONIC

Na Cl

metal non-metal

Opposite sides?

Yes! IONIC

Bonding practice:

C Clnon-metal non-metal

Opposite side?

No!COVALENT

C Cl

2.5 3.0

3.0

-2.5

0.5 >1.8?

No! COVALENT