SCH3U_metallic bond and allotropes January 21, 2015

Intermolecular Forces

Unit 4 Bonding For each of the following molecules, identify the strongest type ofintermolecular forces (van der Waals’ forces, dipole–dipole attractions,hydrogen bonding) they exhibit in the liquid state.a HClb O2

c NH3

d CHCl3e OCl2f SiH4

g N2

h HFi NBr3

How is boiling point/melting point of a substance related to the intermolecular forces? What about the following?

Diamond

IronNaCl

H2O

PCl3

CH4

MetalsConducts Electricity

Malleable

Ductile

Metallic Bond

In a piece of Iron metal, how do the iron atoms bond together?

?

SCH3U_metallic bond and allotropes January 21, 2015

delocalized:

electrons are not confined to a particular locationbut can move throughout the structure.

"sea of delocalized electrons"

What about Diamond?Is diamond an element in the periodic table?

AllotropesThe different structural formsof an element are called allotropes.

Diamond

Graphite

Fullerene

SCH3U_metallic bond and allotropes January 21, 2015

The structure of diamond consists of a giant covalent network latticein which each carbon atom is surrounded by four other carbon atomsbonded in a tetrahedral lattice structure.

The bonding forces are very strong in all three dimensions, resulting in diamond being an extremely hard substance with a very high sublimation point (approximately 3550ºC).

At these extremely high temperatures, the bonds between the carbon atoms are overcome, and they have so much energy that the atoms move straight into the gaseous phase.

Graphite displays many properties fundamentally different from those ofdiamond. It is a soft, greasy solid that is a good conductor of electricity.

In the giant covalent structure of graphite, each carbon atom is bonded to onlythree others in a series of hexagons that make up a layer. As eachcarbon atom has four valence electrons, this leaves one unattached electron for each carbon atom. These delocalized electrons are able to move relatively freely between the layers of strongly bonded carbon atoms, and explains why graphite is such a good conductor of electricity.

Fullerenes (buckyballs)Fullerenes (buckyballs)Fullerenes (buckyballs)Fullerenes

In the late 1970s, a new form of carbon was manufactured by Australianscientist Dr Bill Burch at the Australian National University in Canberra,although he did not go on to investigate its structure. In 1985, Drs RichardSmalley and Robert Curl at Rice University in Houston, Texas, working withHarry Kroto at the University of Sussex, UK, were the fi rst to determine thestructure of this new carbon form, work that was to earn them the NobelPrize in Chemistry in 1996.

each carbon atom is bonded to only three other atoms, resulting in the presence of one free, or delocalized, electron per carbon atom.

SCH3U_metallic bond and allotropes January 21, 2015

Now, let's go back to the beginning.

Diamond

Iron

NaCl

H2O

PCl3

CH4

Summary:

List the following compounds in order of theirboiling points from lowest to highest. Explainyour reasoning in terms of the intermolecularforces present.I Butane (C4H10)II Silicon dioxideIII Propane (C3H8)IV Butanol (C4H9OH)V Sodium chlorideVI 1-Chlorobutane (C4H9Cl)

Next Class:

HL:

Hybridization

Pi and Sigma Bonds

Resonance & Delocalized Electrons

SCH3U_metallic bond and allotropes January 21, 2015

HW: Bonding Worksheet