TOPIC 6- Liquids and Solids Flashcards
The fundamental difference between states of matter is the strength of the
Intermolecular forces of attraction
Stronger intermolecular force
bring molecules closer together
What are the condensed state of matter?
Liquids and Solids
Liquids and Solids are formed by forces that may involve?
Covalent bonding
Ionic Bonding
Intermolecular Forces
They are forces that occur between molecules
Intermolecular Forces (IMF)
The attraction between molecule are not nearly as strong as
intermolecular attractions (bonds)
What are the physical properties that reflect IMF?
Boiling points
Melting points
Viscosity
Surface Tension
Capillary action
What are the types of IMFs?
Dispersion forces
Dipole-dipole forces
Hydrogen Bonding
Ion-dipole forces
What forces are van der Waals forces
Dispersion forces
Dipole-Dipole forces
Instantaneous dipole that occurs in a given atm induces a similar dipole in a neighboring atom which instigates weak and short-lived interatomic attraction.
London Dispersion Forces
It is the tendency of an electron cloud to distort
Polarizability
Factors that affect dispersion force in a molecule are?
- number of electrons in an atom
- size of atom or molecule/molecular weight
- Shape of molecules with similar masses
In London dispersion, more electrons
more dispersion force
In London dispersion, more compact
less dispersion force
It is exhibited by molecules with polar bonds that behave in an electric field
Dipole-dipole Forces
In dipole-dipole forces, as distance between dipoles increase
forces grow weaker
For molecules of approximately equal mass and size, the more polar the molecule
the higher its boiling point
Strong dipole-dipole forces can be noticed when H is bound to highly electronegative atoms like N, O, and F.
Hydrogen Bonding
In Hydrogen bonding, strength can be characterized by:
- Polarity of the bond
- Close approach of the dipoles
- Small size of the H atom
If two molecules are of comparable size and shape,
dipole dipole interaction will likely be dominating force
if one molecule is much larger than another, dispersion forces will likely determine its
physical properties
are found in solutions of ions and the strength of these forces is what makes it possible for ionic substance to dissolve in polar solvent
Ion-dipole interactions
Liquids exhibit?
low compressibility, lack of rigidity and high density
it is the resistance of a liquid to an increase surface area
Surface Tension
Liquids with large intermolecular forces tend to have
high surface tensions
is a spontaneous rising of a liquid in a narrow tube
Capillary Action
attract the liquid to the wall of the tube
Adhesive forces
attract the liquid to itself
Cohesive forces
this refers to the measure of a liquid’s resistance to flow
Viscosity
Liquids with high IMF tend to be?
Highly Viscous
It is the conversion from one state of matter to another
Phase Change
Energy is either _________ or __________ in a phase change
Added, released
what heat is required to change a solid at its melting point to a liquid
Heat of fusion
what heat is required to change a liquid at its boiling point to a gas
heat of vaporization
what heat is required to change a solid directly to a gas
heat of sublimation
A plot of temperature vs. heat added is called
heating curve
the amount of heat needed to raise the temperature of a substance is the product of
specific heat, sample mass, and temperature change
Why does the temperature of a substance does not rise during a phase change?
because the added energy is used to overcome the attractive forces between molecules
During phase change, what is the product of mass and the heat of fusion or vaporization?
Heat
At any temperature, some liquid molecules have enough energy to escape the surface and become gas
Vapor Pressure
As more molecules escape the liquid,
the pressure they exert increases
The vapor pressure present at equilibrium is also called
Equilibrium vapor pressure
Liquids with large intermolecular forces have relatively
low vapor pressure since molecules need a higher energy to escape the vapor phase
Substances with large molar masses have
low vapor pressure since it attributes to larger dispersion forces
Is the temperature at which its vapor pressure equals atmospheric pressure
Boiling Point
is the temperature at which its vapor pressure is 760 torr or 1atm
Normal Boiling Point
temperature at which solid and liquid states have identical vapor pressure and total pressure=1atm
Normal melting point
The natural log of the vapor pressure of a liquid is INVERSELY proportional to its temperature
Clausius-Claude Clapeyron Equation
Convenient way of representing the phase of substance as function of its temperature
Phase Diagrams
The temperature at which all three phases exist simultaneously
Triple Point
The critical pressure and critical temperature, together, define this point.
Critical Point
Pressure required to produce liquefaction at critical temperature.
Critical Pressure
The temperature above with a liquid cannot be liquified, irrespective of pressure applied.
Critical Temperature
What are the two classification of solids?
- Amorphous Solids
- Crystalline Solids
Have disordered structures
Amorphous solids
have a highly regular arrangement of components.
Crystalline Solids
In crystalline solids, position of the components are represented by
lattices
It is a three-dimensional system of points that designates the position of the components of a substance
Lattices
It is the basis of a repeating pattern
Unit Cell
The structure of the crystalline solid is defined by:
- Size and shape of the unit cell
- The locations of atoms within the unit cell.
Positions that define the overall structure of the crystalline compound
Lattice Points
They connect the points and define the unit cell
Lattice Vectors
have atoms only in lattice points
Primitive Lattices
have atoms in another regular location most commonly the body-center or the face-center.
Centered Lattice
Is used to determine the structure of crystalline solids
X-ray Diffraction
Is used to carry out X-ray analysis of crystals.
Diffractometer
What are the types of crystalline solid?
- Ionic Solids
- Molecular Solids
- Atomic Solids
Possess ions at the points of the lattice that describe their structure.
Ionic Solids
Have discrete covalently bonded molecules at each lattice point(s)
Molecular Solids
has atoms at the lattice points that describe its structure
Atomic Solids
Is an arrangement that assumes that metal atoms are hard, uniform spheres
Closest Packing
Forms of closest packing:
- ABA Packing
- ABC Packing
2nd layer is like the first but it is displaced so that sphere in the second layer occupies a dimple in the 1st layer. the spheres in the 3rd layer occupy dimples in the 2nd layer and lie directly over those in the 1st.
ABA Packing
The resultant structure of ABA packig
Hexagonal closest packed (hcp) structures.
When the spheres are aba closest packed, the unit cell is a
hexagonal prism
The spheres in the 3rd layer occupy dimples in the 2nd layer.
ABC packing
Resultant structure in ABC packing
cubic closest packed (CCP) structure
In ABC packing, the unit cell is
Face-centered cubic
Common characteristics of the hcp and the ccp structures
Each sphere in both structure possesses 12 equivalent nearest neighbors
A successful bonding model for metals must consider:
- Malleability
- Ductility
- Efficient uniform conduction of heat and electricity
Bonding models of metal include;
- Electron sea model
- Band Model (molecular orbital model)
A regular array of metal cations are considered to be in a
electron sea model
Mobile electrons conduct
heat and electricity
In electron sea model __________ are explained
thermal conductivity, ductility, and malleability of metals
As the energy of atoms in a chain increases, the energy gap between bonding orbitals and between antibonding orbitals _________-
disappears
Is a substance that contains a mix of elements and possesses metallic properties
Alloy
What are the classifications of alloy
- Substitutional alloy
- Interstitial alloy
- Heterogeneous alloys
some of the host metal atoms are replaced by other metal atoms of similar size
Substitutional Alloy
Some of the holes in the closest packed metal structure are occupied by small atoms
Interstitial alloy
Components not dispersed uniformly
Heterogeneous alloys
are those atomic solids that contain directional covalent bonds which form solids that can be viewed as “giant solids”
Network solids
Properties of network solids:
- Brittle nature
- Ineffective conductors of heat and electricity
Important elements in network solids
Carbon and Silicon
Each C atom is surrounded by a tetrahedral arrangement of other C atoms
Diamond
Slippery, Black, and a conductor of heat and electricity
Graphite
Structure is based on layers of C atoms arranged in fused six-membered rings
Graphite
They have gap between the occupied MOs and the unoccupied ones
Semiconductors
It is changing the conductivity of semiconductors by adding an element with more or fewer electrons
Doping
have more valence electrons than those in the host crystal
N-type semiconductor
have fewer valence electrons than those in the host crystal
P-type semiconductor
Possess strong covalent bonding with molecules but weak forces between molecules
Molecular Solids
the lattice comprises alternately charged ions. held together by strong electrostatic forces
Ionic solids
