Chapter 13: States of Matter

Chapter 13: States of Matter

Basics: Solids, Liquids, Gases

Table of ContentsTable of Contents

Practical Applications

• Intermolecular forces can be used to explain properties of solids, liquids and gases

Practical Applications - GASES• Vapor: the gas phase of a substance that is usually

a liquid at room temperature (as water is)

Practical Applications - GASES• Vapor Pressure

• The pressure of the gas “supported” over a liquid

• Indirectly related to the intermolecular forces within a liquid

• Higher intermolecular forces → more energyneeded to escape → lower vapor pressures →higher boiling points

•Volatility

•Liquids with high vapor pressures (evaporate easier) are volatile

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• Particles are in constant motion

• Fluidity is the ability to flow.

• Gases and liquids are classified as fluids because they can flow.

• A liquid diffuses more slowly than a gas at the same temperature (Why?)

• Because intermolecular attractions interfere with the flow.

Liquids

• Adhesive Forces

• Substances bind to surfaces

• Causes a meniscus

• Cohesive Forces• Binds molecules to each

other

Practical Applications - LIQUIDS

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• Viscosity: the resistance of a liquid to flow.

• ↑ Temperature = ↓Viscosity

• Why?

• With the increase in temperature, there is an increase in the average kinetic energy (velocity) of the molecules.

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• Particles in the middle of the liquid can be attracted to particles above them, below them, and to either side.

• The overall attractive force is pulling down on particles at the surface.

• The energy required to increase the surface area of a liquid

• Surface tension: the inward pull by particles under the surface.

SolidsStates of Matter: Basic ConceptsStates of Matter: Basic ConceptsStates of Matter: Basic ConceptsStates of Matter: Basic Concepts

• Particles are in constant motion.

• For a substance to be a solid rather than a liquid at a given temperature, there must be stronger ________ _________ acting between particles in the solid.

attractiveforces

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• REMINDER: These forces limit the motion of the particles

• vibrations around fixed locations

• More order - not classified as fluids

• Dense: particles are closely packed

• Without looking at your notes, give a detailed description of each phase

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• Crystalline solids: solids which have a well defined arrangement

• Flat surfaces - Definite angles

• A lattice: the 3D structure of a crystalline solid.

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• Crystalline solids: solids which have a well defined arrangement

• A unit cell: the smallest arrangement of connected points that can be repeated to form the lattice.

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• Crystalline solids: solids which have a well defined arrangement

• Crystals: the individual pieces of a crystalline solid.

• ex) quartz, diamond

Crystalline solids

Type Unit particles

atomic Atoms (noble gases)

molecular Molecules (nonmetals)

covalent network (strongest)

atoms connected by covalent bonds

(Cdia, Si, SiO2, SiC, Cgra)

ionic Ions (metal + nonmetal)

metallic atoms surrounded by mobile valence electrons (metals)

• Crystalline solids can be classified into 5 categories based on the types of particles they contain:

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• Amporphous solids: No orderly structure

• Lack of well defined faces or angles

• ex) rubber, glass

Tell the difference between crystalline and amorphous solids

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• Remember:

• Ionic solids dissolve in water, conduct electricity and heat

• Covalent/Amorphous solids do not dissolve in water, conduct electricity and heat