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85 Cards in this Set
- Front
- Back
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Are most bonds fully ionic or fully covalent?
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No, most are somewhere in between
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What is the symbol for partial charge?
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Either δ- or δ+
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δ name?
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delta
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electronegativity (EN)
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the intrinsic ability of an atom to attract the shared electrons in a covalent bond
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What element is the most electronegative?
EN = ? |
fluorine (EN = 4)
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Which element is the least electronegative?
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cesium (EN = 0.7)
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In general, bonds between atoms whose electronegativities differ by less than 0.5 are:
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nonpolar covalent
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In general, bonds between atoms whose electronegativities differ by 0.5 to 2 are:
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polar covalent
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In general, bonds between atoms whose electronegativities differ by 2 or higher are:
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typically ionic
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In the image, how would a cross arrow be drawn to indicate the direction of bond polarity?
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inductive effect
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the shifting of electrons in a sigma bond in response to the electronegativity of nearby atoms
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Symbol for dipole moment?
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μ
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μ name?
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mu
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dipole moment (formula)
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μ = Q x r
the magnitude of the charge Q at either end of the molecular dipole times the distance r between the charges |
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What substance is responsible for the odor of rotting fish?
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methylamine
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x
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x
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What's the only difference between resonance structures?
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the placement of the pi or nonbonding valence electrons
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What drawing is correct? Draw the answer.
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Both, as resonance structures
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Does resonance lead to stability? Why?
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Yes! Generally, the larger the number of resonance forms, the more stable a substance is because electrons are spread out over a larger part of the molecule and are closer to more nuclei.
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Draw the 3 resonance forms for the carbonate ion, CO3^2-
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radical
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a substance that contains a single, unpaired electron in one of its orbitals
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Bronsted-Lowry acid
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a substance that donates a proton (H+)
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Bronsted-Lowry base
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substance that accepts a proton
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conjugate acid
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the result of the base structure accepting a proton
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conjugate base
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the resulting structure after protonation
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Keq is what?
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equilibrium constant
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What does brackets [] around a substance mean?
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that the concentration of the enclosed species is given in moles per liter, M
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Ka is?
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acidity constant?
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acidity constant is?
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the equilibrium constant for the acid dissociation multiplied by the molar concentration of pure water
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For acid strength, what value is normally used instead of Ka?
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pKa
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pKa is?
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pKa = -logKa
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strong acids have a ____ Ka and a ____ pKa
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strong acids have a larger Ka and a smaller pKa
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formula for hydrocyanic acid?
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HCN
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Formula for acetic acid?
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CH3CO2H
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Formula for phosphoric acid?
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H3PO4
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Formula for nitric acid?
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HNO3
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formula for cyanide?
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CN-
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formula for hydrochloric acid?
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HCl
Very strong acid |
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a strong acid has a ______ conjugate base
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weak
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a weak acid has a ____ conjugate base
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strong
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In comparing two acids, the one with the lower pKa is _____
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stronger
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positively polarized areas will appear _____ in an electrostatic potential map
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blue
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negatively polarized areas will appear _____ in an electrostatic potential map
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red
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carboxylic acids
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compounds containing the --CO2H grouping
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Draw pyruvic acid
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draw citric acid
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organic bases are characterized by:
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the presence of an atom (reddish in electrostatic potential maps) with a lone pair of electrons that can bond to H+
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amino acids
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substances containing both amines (--NH2) and carboxylic acids (--CO2H)
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amine
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--NH2
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carboxylic acid
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--CO2H
or --COOH |
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How many different amino acids may go into protein building?
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20
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zwitterion
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a molecule with a positive and a negative electrical charge on different atoms within the molecule.
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inner salts
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another name for zwitterions
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Lewis acid
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a substance that accepts an electron pair
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Lewis base
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a substance that donates an electron pair
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The fact that a Lewis acid is able to accept an electron pair means that it must have either....
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The fact that a Lewis acid is able to accept an electron pair means that it must have either....
...a vacant, low energy orbital or a polar bond to a hydrogen so that it can donate H+ |
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Is Mg^2+ an acid?
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Yes, it's a Lewis acid because it can accept a pair of electrons when forming a bond to a base.
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Many transition-metalcompounds, such as TiCl4, FeCl3, and SnCl4 are _________
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Lewis acids
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Which is the Lewis acid and which is the Lewis base?
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A curved arrow always means...
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A curved arrow always means...
that a pair of electrons move from the atom at the tail of the arrow to the atom at the head of the arrow |
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Name 3 different types of noncovalent interactions
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dipole-dipole forces
dispersion forces hydrogen bonds |
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van der Waals force
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the sum of the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral molecules.
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dipole-dipole forces
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occur between polar molecules as a result of electrostatic interactions among dipoles
can be either attractive or repulsive, depending on molecular orientation |
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Which is predominant, attractive or repulsive dipoles?
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attractive, because the geometry is lower in energy
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dispersion forces
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occur between all neighboring molecules and arise because the electron distribution within molecules is constantly changing
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hydrogen bond
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the attractive interaction between a hydrogen bonded to an electronegative O or N atom and an unshared electron pair on another O or N atom
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What sort of bond is used to hold DNA strands together?
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hydrogen bonds
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hydrophilic
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means water loving; describes substances that dissolve in water
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hydrophobic
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means water fearing; describes substances insoluble in water
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alkaloid
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a group of naturally occurring chemical compounds which mostly contain basic nitrogen atoms
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What chemistry occurs when lemon juice is added to fish?
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the citric acid reacts with the methylamine, masking the odor
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Scientific name for the opium poppy?
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Papaver somniferum
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draw morphine
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draw cocaine
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What's the EN of carbon?
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2.5
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Which is more electronegative, sulfur or carbon?
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Neither, they are equal.
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Ethylene glycol, HOCH2CH2OH, has zero dipole moment even though carbon-oxygen bonds are strongly polarized. Explain.
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The dipole moment of ethylene glycol is zero because the bond polarities of the two carbon-oxygen bonds cancel.
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formal charge =
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= (# of valence e- in free atom) - (# of valence e- in bonded atom)
= (# valence e- in free atom) - (# of bonding electrons /2) - (# of nonbonding e- ) |
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A substance has a low pKa. It must be:
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acidic
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If pKa = 19.3, what is the Ka?
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5.01e-20
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If the Ka is 5.0e-11, what is the pKa?
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10
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Can atoms change positions in resonance forms? What about electrons?
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No, atoms cannot! Only electrons can!!
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