Topic: Chemical Bonding

chemical bond

• A chemical bond is a electrostatic force between atoms (caused by electrons attracting to the positive nucleus of another atom)

Why do atoms form bonds?

To attain a noble gas configuration

How do atoms form chemical bonds?

By gaining, losing, or sharing electrons

A + B ABWhen a bond formed = energy is released = reaction is exothermic

BBreaking a Bond reaking a Bond AAbbsorbs Energy sorbs Energy (endothermic)!(endothermic)!

•When a chemical bond is formed, PE is released, the bond becomes more

stable

• You have to put energy in to brake a chemical bond, so PE increases and the overall system becomes less stable

Ionic Bonding

Occurs between?

(type of elements)

Electrons (shared or transferred?)

• Metals and nonmetals

• Transferred, metal loses, nonmetal gains

electron transferred from Na to Clelectron transferred from Na to Cl

The more Na and ClThe more Na and Cl22, the , the larger the resulting NaCl larger the resulting NaCl crystal crystal

-just keep adding on to it-just keep adding on to it

Structure of Ionic Compounds

• Ions form crystal lattice – regular 3-D pattern

or array – Ions held in fixed

positions (solid state)

Ionic Bonding

Type of structure?

Properties

• Crystal Lattice

• High Boiling Point, High Melting Point, Hard, Brittle, Conduct electricity if melted or in solution (dissolved in water)

lattice structure lattice structure

NaCl has its own NaCl has its own unique propertiesunique properties

Metallic Bonding

Occurs between?

(type of elements)

Electrons (shared or transferred?)

• Metals

• Mobile sea of electrons

Metallic Bonding

Type of structure?

Properties

• Crystal Lattice

• High Boiling Point, High Melting Point, Hard, Good Conductors electricity

Covalent Bonding

Occurs between?

(type of elements)

Electrons (shared or transferred?)

• Nonmetals only

• shared

Covalent Bonding

Type of structure?

Properties

• Molecules – held together by IMF (intermolecular forces)

• Low Boiling Point, Low Melting Point, soft, poor conductors of electricity

Identify Bond Type from Formula

ZnOZnONN22OO55AlAl

CHCH33OHOHAlAl22OO33CaBrCaBr22

AuAuAgAgCOCO22

LiLi33NNNaNa22SSMgMg

CsFCsFHH22OONaClNaCl

SOSO22CuCuCHCH44

CovalentCovalent

CovalentCovalent

CovalentCovalent

CovalentCovalent

CovalentCovalent

CovalentCovalent

IonicIonic

IonicIonic

IonicIonic

IonicIonic

IonicIonic

IonicIonic

IonicIonic

MetallicMetallic

MetallicMetallic

MetallicMetallic MetallicMetallic

MetallicMetallic

So what? Why is structure so important?

Structure determines physical properties!