CHEM 51A MIDTERM #1 QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026
Electrons/lone pairs - Answers Curly arrows show movement of ______________
Linear - Answers Geometry where the bond angle is 180 degrees, atom is surorunded by 2 groups
Trigonal planar - Answers Geometry where the bond angle is 120 degrees, atom is surrounded by 3
groups
Tetrahedral - Answers Geomertry where the bond angle is 109.5 degrees, atom is surrounded by 4
groups
sp^3 - Answers Hybridization with 4 bonds to C, 25% s character, 75% p character
sp^2 - Answers Hybridization with 3 bonds to C, 33% s character, 67% p character
sp - Answers Hybridization with 2 bonds to C, 50% s character, 50% p character
s - Answers The more _____ character, the more stable the atom is.
shorter - Answers The _______ the bond, the stronger the bond
Bronsted-Lowry acid - Answers a substance that donates a proton to another substance
Bronsted-Lowry base - Answers a substance that accepts a proton
Lone pair - Answers The __________ on the base has become a bond between the base and proton
Bond - Answers The __________ between the proton and acid has become a lone pair on the acid
lower - Answers The _________ the pKa, the stronger the acid
higher - Answers The __________ the pKa, the stronger the base
increases - Answers Going across the periodic table, acidity ________ due to higher electronegativity
(more stable conjugate bases)
increases - Answers Going down the periodic table, acidity ________ due to size, which smears the
negative charges
Lewis Acid - Answers an atom, ion, or molecule that accepts an electron pair to form a covalent bond
Lewis base - Answers an atom, ion, or molecule that donates an electron pair to form a covalent bond
Hydrocarbon - Answers Compounds composed of only carbon and hydrogen
Heteroatoms - Answers Atoms in an organic compound other than carbon and hydrogen
Pi bonds - Answers Included in double and triple bonds only, can be donated as electrons
Alkyl halide - Answers Has a carbon chain with a -X (halo group)
Alcohol - Answers Carbon chain with an -OH (hydroxyl) group
Ether - Answers Carbon chains connected with an O (alkoxy) group (R-O-R)
Amine - Answers Carbon chain with an NH2 or NH (amino) group
Thiol - Answers Carbon bonded to a SH group
Sulfide - Answers Carbon chains connected by an S --> R - S - R
Alkanes - Answers Carbon groups that containe only single bonds, end in -ane
Alkenes - Answers Carbon groups that contain one or more pi bonds, en in -ene
Alkynes - Answers Carbon groups that contain one or more triple bonds, end in -yne
Aldehyde - Answers End of carbon chain that is double bonded to an O (R-C(H)=O, carbonyl group)
Ketone - Answers Carbon chain with a double bonded O in the middle (carbonyl group) R - C(=O) - R
Carboxylic acid - Answers Carbon chain with a double bonded O and alcohol at the end (R - C(=O) -
OH)
Ester - Answers Carbon chains connected by double bonded O and single bonded O (R - C(=O) - O - R)
Amide - Answers Carbon chain with a double bonded O and an amine group (R - C(=O) - NH)
Acid chloride - Answers Carbon chain with a double bonded O and a chloride atom R - C(=O) - Cl
Van der waals forces - Answers Unsymmetrical electron density creates a temporary dipole between
atoms, weak overall but strong in aqueous solution
Dipole-dipole forces - Answers Atoms align to maximize interaction and stability, moderately strong
forces
Hydrogen bonding - Answers Special type of dipole-dipole force between N,O,F and hydrogen, strong
overall but weak in aqueous solution. Hydrogen is the H-bond donor, and X is the h-bond acceptor
stronger - Answers The ____________ the IMFs, the higher the melting/boiling point.
lowest - Answers The compound with the __________ boiling point will be distilled first.
increase - Answers Symmetry and compactness ____________ melting point.
five - Answers One polar functional group for every _________ carbons indicates water solubility.
Electrophiles - Answers Acceptors of electrons (aka Lewis Acids) --> electron deficient
Nucleophiles - Answers Donators of electrons/pi bonds (aka Lewis bases) --> electron rich
Carboneals - Answers Best electrophiles, hate to have a + charge
Electrons/lone pairs - Answers Curly arrows show movement of ______________
Linear - Answers Geometry where the bond angle is 180 degrees, atom is surorunded by 2 groups
Trigonal planar - Answers Geometry where the bond angle is 120 degrees, atom is surrounded by 3
groups
Tetrahedral - Answers Geomertry where the bond angle is 109.5 degrees, atom is surrounded by 4
groups
sp^3 - Answers Hybridization with 4 bonds to C, 25% s character, 75% p character
sp^2 - Answers Hybridization with 3 bonds to C, 33% s character, 67% p character
sp - Answers Hybridization with 2 bonds to C, 50% s character, 50% p character
s - Answers The more _____ character, the more stable the atom is.
shorter - Answers The _______ the bond, the stronger the bond
Bronsted-Lowry acid - Answers a substance that donates a proton to another substance
Bronsted-Lowry base - Answers a substance that accepts a proton
Lone pair - Answers The __________ on the base has become a bond between the base and proton
Bond - Answers The __________ between the proton and acid has become a lone pair on the acid
lower - Answers The _________ the pKa, the stronger the acid
higher - Answers The __________ the pKa, the stronger the base
increases - Answers Going across the periodic table, acidity ________ due to higher electronegativity
(more stable conjugate bases)
increases - Answers Going down the periodic table, acidity ________ due to size, which smears the
negative charges
Lewis Acid - Answers an atom, ion, or molecule that accepts an electron pair to form a covalent bond
Lewis base - Answers an atom, ion, or molecule that donates an electron pair to form a covalent bond
Hydrocarbon - Answers Compounds composed of only carbon and hydrogen
Heteroatoms - Answers Atoms in an organic compound other than carbon and hydrogen
Pi bonds - Answers Included in double and triple bonds only, can be donated as electrons
Alkyl halide - Answers Has a carbon chain with a -X (halo group)
Alcohol - Answers Carbon chain with an -OH (hydroxyl) group
Ether - Answers Carbon chains connected with an O (alkoxy) group (R-O-R)
Amine - Answers Carbon chain with an NH2 or NH (amino) group
Thiol - Answers Carbon bonded to a SH group
Sulfide - Answers Carbon chains connected by an S --> R - S - R
Alkanes - Answers Carbon groups that containe only single bonds, end in -ane
Alkenes - Answers Carbon groups that contain one or more pi bonds, en in -ene
Alkynes - Answers Carbon groups that contain one or more triple bonds, end in -yne
Aldehyde - Answers End of carbon chain that is double bonded to an O (R-C(H)=O, carbonyl group)
Ketone - Answers Carbon chain with a double bonded O in the middle (carbonyl group) R - C(=O) - R
Carboxylic acid - Answers Carbon chain with a double bonded O and alcohol at the end (R - C(=O) -
OH)
Ester - Answers Carbon chains connected by double bonded O and single bonded O (R - C(=O) - O - R)
Amide - Answers Carbon chain with a double bonded O and an amine group (R - C(=O) - NH)
Acid chloride - Answers Carbon chain with a double bonded O and a chloride atom R - C(=O) - Cl
Van der waals forces - Answers Unsymmetrical electron density creates a temporary dipole between
atoms, weak overall but strong in aqueous solution
Dipole-dipole forces - Answers Atoms align to maximize interaction and stability, moderately strong
forces
Hydrogen bonding - Answers Special type of dipole-dipole force between N,O,F and hydrogen, strong
overall but weak in aqueous solution. Hydrogen is the H-bond donor, and X is the h-bond acceptor
stronger - Answers The ____________ the IMFs, the higher the melting/boiling point.
lowest - Answers The compound with the __________ boiling point will be distilled first.
increase - Answers Symmetry and compactness ____________ melting point.
five - Answers One polar functional group for every _________ carbons indicates water solubility.
Electrophiles - Answers Acceptors of electrons (aka Lewis Acids) --> electron deficient
Nucleophiles - Answers Donators of electrons/pi bonds (aka Lewis bases) --> electron rich
Carboneals - Answers Best electrophiles, hate to have a + charge
