Intermolecular Forces of Attraction

Intermolecular Forces of Attraction

General Chemistry II _________________________ SY: 2021 - 2020 By Kei Pangilinan

Objectives for the day

After this day you'll be able to:

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1. Describe and differentiate the types of

   intermolecular forces and;

2. Write dow​n the important parts of a Laboratory Paper in preparation for the activity next meeting.

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General Chemistry II ________________ SY 2021 - 2022​

Multiple Choice

Take a look at the picture, how many phases of matter can you see?

• 1

• 2

• 3

• 4

Intermolecular Forces of Attraction?​

Intermolecular forces are attractive forces between molecules.

​Intramolecular forces hold atoms together in a molecule.

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​Intermolecular vs Intramolecular

41 kJ to vaporize 1 mole of water (inter)

930 kJ to break all O-H bonds in 1 mole of water (intra)

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boiling point

melting point

ΔH_vap

ΔH_fus

ΔH_sub

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“Measure” of intermolecular force

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Generally, intermolecular forces are much weaker than intramolecular forces.

TAKE NOTE!

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Dipole-Dipole Forces

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Attractive forces between polar molecules

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Ion Dipole Forces

Attractive forces between an ion and a polar molecule

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Dispersion Forces

Attractive forces that arise as a result of temporary dipoles induced in atoms or molecules. Mostly appears in gases.​

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Hydrogen Bonding

The hydrogen bond is a special dipole-dipole interaction between they hydrogen atom in a polar N-H, O-H, or F-H bond and an electronegative O, N, or F atom.

Properties of Liquids

Surface tension is the amount of energy required to stretch or increase the surface of a liquid by a unit area.

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Properties of Liquids

Cohesion is the intermolecular attraction between like molecules.

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​Adhesion is an attraction between unlike molecules​

Properties of Liquids

Viscosity is a measure of a fluid’s resistance to flow.

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Solids

​A crystalline solid possesses rigid and long-range order. In a crystalline solid, atoms, molecules or ions occupy specific (predictable) positions.

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​An amorphous solid does not possess a well-defined arrangement and long-range molecular order.

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Types of Crystal

Ionic Crystals​

• Held together by electrostatic attraction

• Hard, brittle, high melting point

• Poor conductor of heat and electricity

Types of Crystal

Covalent Crystals​

• Held together by covalent bonds

• Hard, high melting point

• Poor conductor of heat and electricity

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Types of Crystal

Molecular Crystals​

Lattice points occupied by molecules

Held together by intermolecular forces

Soft, low melting point

Poor conductor of heat and electricity

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Types of Crystal

Metallic Crystals

Lattice points occupied by metal atoms

Held together by metallic bonds

Soft to hard, low to high melting point

Good conductors of heat and electricity

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Multiple Choice

What do you call the forces that hold atoms together?

• Intermolecular Forces of Attraction

• Intramolecular Forces of Attraction

• Hypermolecular Forces of attraction

• Hyperatomic Forces of Attraction

Multiple Choice

Higher melting point means...

• It requires more energy to break the bonds of a molecule before it starts melting

• It requires less energy to break the bonds of a molecule before it starts melting

• It requires more energy to break the bonds of a molecule before it starts freezing

• It requires less energy to break the bonds of a molecule before it starts freezing

Multiple Choice

Which intermolecular force of attraction is the weakest?

• Dipole-Dipole

• Ion-dipole

• Hydrogen-bonding

• Dispersion Forces

Multiple Choice

True or False: The stronger the intermolecular force, the easier to break bonds.

• TRUE

• FALSE

Multiple Choice

Which type of crystal is the best conductor of electricity?

• Ionic

• Covalent

• Molecular

• Metallic

Multiple Choice

What kind of intermolecular force of attraction exists in dry ice?

• Hydrogen bonding

• Dispersion forces

• Ion-dipole

• Dipole-dipole