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