Chapter 11 - Physical Properties and Chemical Reactivity!! Flashcards
boiling
liquid to gas phase change
melting
solid to liquid phase change
how does melting/boiling happen?
energy disrupts intermolecular forces present
intermolecular forces def and different types
electrostatic forces that occur between atoms, ions, molecules
dipole - dipole, hydrogen bonding, london (dispersion) forces
are covalent bonds broken in melting or boiling?
NO!!!
solubility
the ability to form a solution with a substance
like dissolves like (ex non polar x non polar or polar x polar)
what happens when a substance is dissolved in a liquid?
ions are separated and interact with solvent molecules.
ionic compound dissolves if the resulting intermolecular forces strong enough to overcome forces of attraction between ions
dipole - dipole interaction
electrostatic attraction between partial positive charge one molecule and partial negative on other
higher boiling point than non polar, middle of strengths
can be attractive (opposite charges) or repulsive (same charges)
attractive results in greater coulombic force therefore stronger than repulsive
hydrogen bond
dipole dipole interation between a hydrogen atom and N, O, or F (all very electronegative atoms)
the H-N H-O H-F bonds are SUPER polar and interact with other electronegative atoms to form a hydrogen bond
Strongest intermolecular force, but not as strong as covalent
london force OR dispersion force OR london dispersion force
interactions between instantaneous dipoles, which could influence the distribution of atoms in adjacent atoms, resulting in induced dipole in the other atom and temporary electrostatic attraction between them
weaker of the intermolecular forces, could be more significant for large species
occurs in ALL atoms, ions, molecules etc
polarizability
ease with which electron distribution in atom or molecule is distorted
larger atoms are more distortable because held less tightly by nucleus, therefore london dispersion forces are stronger and more energy is required to interupt intermolecular forces therefore higher boiling point
van der waals forces
include dipole-dipole, hydrogen, and london forces
what distance do dipole dipole interactions need based on r (distance between centres)
1/(r^3)
what distance to london (dispersion) forces need based on r (distance between centres)
1/(r^6)
how does hydrogen bonding in h2o affect the way ice floats on water?
when solid, water forms an ordered crystal structure in which hydrogen bonds are held still and are slightly further apart than in liquid water
this means ice is less dense than water and thus floats on top
deprotation
removal of a proton (or hydron or hydrogen cation) from a Bronsted-Lowry acid
deprotation
removal of a proton (or hydron or hydrogen cation) from a Bronsted-Lowry acid
carboxylic acid group
organic acid containing a carboxyl group attached to an R-group
general formula A-COOH or R-CO2H
ionic solid
consist of positive and negative atomic and/or molecular ions
strongly attracted to one another and form a crystal lattice
coulombs law
energy of electrostatic attraction between a cation and an anion proportional to magnitude of two charges and inversely proportionate to distance between nuclei
E (squiggly proportionate symbolnot =) = [(n)*(m)]/dM-X
where n is charge of cation (+)
m is charge of anion (-)
dM-X is distance between ion centres
lattice energy
energy required to convert one mole of crystalline solid into constituent ions at infinite separation in the gas phase (completely break intermolecular forces, sepeaate into ions)
units: kJ/mol
magnitude proportional to how strongly ions attract one another in ground state - stronger intermolecular forces, more energy required to break therefore greater lattice energy
metallic bonding
electrons are able to move through a sample of metal because the difference between the ground state and excited state is very small\
interactions between atoms strong, so high melting and boiling point
conduct electricity, electrons can travel through metal wire in a circuit
molecular solids
to exist as solid at room temp and pressure, intermolecular forces large enough to hold atoms relatively still
network covalent solids
solids held together by bonds forming extended array
IMPORTANT very high melting and boiling points because covalent bonds must be broken, no other solid requires covalent bonds to be broken
polar and non polar molecular solids, atoms covalently bonded forming discrete molecules
ionic solids weaker dipole-dipole or london forces hold molecules together to form the solid
network covalent solids are network solids atoms held together by covalent bonds
allotropic
elements which exist in more than one form in the same physical state
ex white phosphorus (a molecular solid) 4 covalently bonded phosphoruses as a tetrahedron, highly reactive
(^ reactive because 60 degree bond angles)
red phosphorus 4 phosphoruses in linear chains, one bond broken and too another, less strain, less reactive
black phosphorus, forms sheet structure, non as reactive, less strained
condensation reaction
covalent bond formed with the release of a small molecule (ex water)
chemical change
essentially two larger molecules bonding, and each gives a couple atoms that form a smaller molecule as well - rxn of two molecules resulting in 2 molecules one being super small
soap micelles
oils etc arent soluble in water
soap molecules oriented in micelle (made of multiple molecules), dirt etc trapped on inside of the micelle (by non -polar “tails” of soap molecule), charged heads of soap molecule allow micelle suspended in water
triacyclglycerols
contain 3 ester functional groups - broken apart by strong base ex hydroxide (saponification)
3 fatty acids and a molecule of glycerol
each fatty acid has a carboxylic acid functional group, can combine w glycerol form ester functional groups
what are lipids used for in people?
source of energy, energy storage, in cell membrane structure, as hormonal messengers
2 common lipid types
tricylglycerols
steroids
functional groups
covalently bonded groups w predictable chemical behaviour (ex ability to undergo chemical reactions
chem reaction to form a triacylglycerol
dehydration
essentially removing an h from glycerol and on oh from fatty acids to form H2O and the glycerol and fatty acid combine
fatty acid
straight chain of even number carbon atoms, hydrogen atoms along length and at one end and carboxyl group -cooh at other end (which makes it an acid)
vary in length and where double bonds are along the chain
in nature carbon chain length varies from 4 to 28
building blocks of fats
ester
organic compound made by replacing hydrogen if an acid w an alkyl or other organic group
monosaturated fats
fat containing one double bond
location influences properties
polysaturated fats
contain more than one double bond
location influences physcial properties
what does Si form?
network covalent solids
what does SiO2 form?
network covalent solids
what do diamond and graphite form? what are they?
network covalent solids
allotropes of carbon
saturated vs unsaturated hydrocarbons
saturated contain only single carbon carbon bonds while unsaturated contain at least one double - unsaturated are more reactive
copy and pasted word for word explanation of trends in saturated vs unsaturated fatty acids
saturated and has the highest melting point, mono-unsaturated (i.e., has one
C=C double bond) giving it a lower melting point, di-unsaturated lowest
melting point.
The tetrahedral bond angles on the sp3 hybridized carbons results in an overall molecular geometry for
saturated fatty acids, such as stearic acid, that is relatively linear (albeit “zig-zagging”). This allows the
fatty acid molecules to closely “stack” together in the solid. The close intermolecular interactions result
in relatively high melting points.
In contrast, the presence of one or more planar double bonds (sp2 hybridized carbons) in the
hydrocarbon chain of unsaturated fatty acids results in one or more “bends” in the molecule. These
molecules do not “stack” very well, thus weakening their intermolecular interactions. As a result, the
melting points are lower for unsaturated fatty acids, such as oleic acid (and even more so, linoleic acid)
than for saturated ones.
