Chemical Bonding revised

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Slide 41

Network Solids

Like ionic crystals, but they are held together with covalent bonds

Single elements can form an array of different network solids

Eg. Carbon forms graphite, diamond, nanotubes (pg. 60)

Slide 42

Each different network solid of the same element just has different arrangement of the atoms

Some network solids contain two different elements

Eg. Silicon Dioxide (sand, quartz)

Slide 43

Questions

Slide 44

Intermolecular Forces

Covalent bonds exist between atoms within a molecular compound

These covalent bonds are called intramolecular forces

Forces holding entire molecules together are called intermolecular forces

Slide 45

Dipole-Dipole Forces

Occurs between polar molecules

Polar molecules have a positive pole and a negative pole so they are called dipoles

When two dipoles come close to each other, the positive pole of one is attracted to the negative pole of the other

Slide 46

Dipole-Dipole Attractions

Slide 47

Each molecule can be attracted to four or more other polar molecules at the same time

This is called Dipole-Dipole Attraction

Not as strong as ionic attraction, but can be strong enough to stabilize a solid crystal

Eg. Table sugar

Slide 48

Hydrogen Bonding

Special dipole-dipole attraction that occurs between hydrogen and highly electronegative atoms such as oxygen, nitrogen, or fluorine

The positive nucleus of the hydrogen atom is attracted to the slightly negative charge on the other atom

Much stronger than other dipole-dipole attractions

Slide 49

Slide 50

Hydrogen Bonding in Water

Hydrogen bonding is an important factor that influences the structure and properties of water

One oxygen atom can be hydrogen bonded to as many as 6 other hydrogen atoms in other water molecules

Slide 51

Hydrogen Bonds in Ice