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WorksheetsChemistry Unit 3
Total questions: 100
Worksheet time: 50mins
Which statement best defines intermolecular forces (IMFs)?
Attractions between molecules due to electrostatic effects
Attractions between ions forming ionic bonds
Attractions causing nuclei to fuse into larger atoms
Attractions between atoms within one molecule
Compared to chemical bonds, IMFs are generally
stronger and more permanent interactions
weaker and involve no true bonding
unrelated to molecular properties
equal in strength and permanence
Which physical property typically increases as IMFs become stronger?
Boiling point of a pure substance
Volatility of a nonpolar gas
Ease of evaporation at room temperature
Vapor pressure of a liquid sample
Which set correctly pairs high IMFs with the property trend?
Boiling point
Higher value
Vapor pressure
Lower value
Viscosity
Higher value
Surface tension
Higher value
Hydrogen bonding doesn't occur when H is bonded to which of these atoms in a molecule?
Chlorine atoms in a molecule
Nitrogen atoms in a molecule
Oxygen atoms in a molecule
Fluorine atoms in a molecule
Why are hydrogen bonds significant in biology?
They create metallic bonding in cells
They ionize all amino acids fully
They prevent diffusion across membranes
They hold DNA bases together in pairs
Water has a high specific heat primarily because
its electrons are fully delocalized
its low mass increases heat capacity
its ionic bonds absorb heat strongly
its hydrogen bonds require energy to disrupt
Which statement about hydrogen bonds is accurate?
They are chemical bonds forming new compounds
They are relatively weak but crucial for life
They occur only in gaseous hydrogen
They are strongest at very high temperatures
Dipole-dipole forces arise between
opposite partial charges of polar molecules
two nonpolar molecules without charges
ionic crystals with full charges
atoms in a metallic lattice
Which example illustrates an induced dipole moment?
O2 becoming temporarily attracted to water
NaCl dissolving into separate ions
N2 permanently gaining ionic charge
H2O forming covalent bonds with O2
Cold water holds more dissolved oxygen than warm water because
oxygen reacts chemically at low temperature
molecules move slower, enhancing attractions
salts increase permanent dipoles
colder water forms stronger covalent bonds
Which statement about London dispersion forces (LDFs) is correct?
They result from temporary electron clumping
Only polar molecules exhibit LDFs
They are permanent and direction-specific
They require hydrogen directly bonded to O
Which substances can experience only London dispersion forces between their particles?
Noble gases like neon and argon
Hydrogen-bonded liquids like HF
Ionic salts like sodium chloride
Polar molecules like HCl gas
How does polarizability affect LDF strength?
Polarizability only affects ionic compounds
Greater polarizability strengthens dispersion forces
More electrons reduce polarizability significantly
Fewer electrons always increase polarizability
Match the IMF type to the key description.
Hydrogen bonding
Strong dipole with H–F, H–O, or H–N
Dipole-dipole forces
Attraction between polar molecules
London dispersion forces
Instantaneous dipoles from electron movement
Which statement best explains why molecular shape matters in chemistry?
Shape affects polarity and charge of molecules
Shape only changes the molecule’s mass value
Shape controls nuclear stability in the atoms
Shape determines isotope ratios in elements
According to VSEPR theory, what causes the arrangement of electron sets around a central atom?
Repulsion between valence electron sets maximized
Attraction between paired and unpaired electrons
Gravitational pull from the nucleus on bonds
Magnetic alignment of electron spin directions
Which statement correctly compares lone pairs and shared pairs in VSEPR?
Shared pairs repel more strongly than lone pairs
Lone pairs repel more strongly than shared pairs
Both pairs have equal repulsion strengths
Neither pair contributes to molecular geometry
Which description matches a sigma (σ) bond?
Head‑to‑head overlap of orbitals forming first bonds
Side‑by‑side p orbital overlap in multiple bonds
Electrostatic attraction without orbital overlap
Overlap only between d orbitals in transition metals
Which bonds are created by side‑by‑side overlap and occur in double or triple bonds?
Pi (π) bonds
Sigma (σ) bonds
Hydrogen bonds
Ionic bonds
Match each molecular shape with its key parameter set.
Linear
180° bond angle; AB2 formula
Trigonal‑planar
120° bond angles; AB3 formula
Both shapes
All atoms in one plane
Which molecules are correctly classified by their ideal VSEPR shapes?
BeF2 as linear with 180° angle
H2O as trigonal‑planar due to AB3
CO2 as linear due to two regions
BF3 as trigonal‑planar at 120°
Which molecular geometry has two atoms bonded to the central atom, bond angles greater than 120°, and the basic formula AB2E?
Bent planar with AB2E
Trigonal planar with AB3
Linear shape with AB2
Tetrahedral with AB4
Water (H2O) is best described by which set of features?
Tetrahedral, 109.5° angles, AB4
Bent planar, >120° angles, AB2E
Trigonal planar, 120° angles, AB3
Bent pyramidal, 104.5° angles, AB2E2
Which statement correctly matches geometry, bond angles, and base formula for a tetrahedral molecule like CH4?
Octahedral, 90° vertical and horizontal, AB6
Tetrahedral, 109.5° angles, AB4
Trigonal-pyramidal, 107° angles, AB3E
Trigonal-bipyramidal, 90° and 120°, AB5
Ammonia (NH3) has which molecular geometry and basic formula?
Bent planar, AB2E
Trigonal-bipyramidal, AB5
Tetrahedral, AB4
Trigonal-pyramidal, AB3E
Phosphorus pentachloride (PCl5) exhibits which ideal bond angles and base formula?
180° only, AB2
90° axial and 120° equatorial, AB5
109.5° all around, AB4
104.5° all around, AB2E2
Match each molecular geometry to its example compound.
Bent pyramidal (AB2E2)
H2O
Tetrahedral (AB4)
CH4
Trigonal-pyramidal (AB3E)
NH3
Trigonal-bipyramidal (AB5)
PCl5
Octahedral (AB6)
SF6
Which features define an octahedral molecule such as SF6?
Vertical and horizontal angles are 90°
Basic formula AB6 applies
Contains one lone pair on the apex
Internal angles include 120° in a plane
Six atoms bonded to the central atom
Which statements describe orbital hybridization during covalent bonding in carbon?
Electrons occupy unchanged original s and p orbitals
Orbitals of similar energies mix to equal energies
Hybridized orbitals form equivalent covalent bonds
Mixing occurs between different atoms’ orbitals only
An s electron promotes to an empty p orbital
Which set describes a molecule that is linear with bond angles of 180°?
4 bonded atoms, 0 lone pairs, sp3
2 bonded atoms, 0 lone pairs, sp
3 bonded atoms, 0 lone pairs, sp2
2 bonded atoms, 1 lone pair, sp2
BF3 has which combination of geometry and hybridization at the central atom?
Trigonal planar, sp2
Tetrahedral, sp3
Trigonal pyramidal, sp3
Linear, sp
Which statement best explains why H2O has a bond angle less than 109.5°?
Two lone pairs compress the H–O–H angle
Oxygen uses sp hybrid orbitals only
Water is trigonal planar at oxygen
There is no lone pair repulsion present
Match each molecular formula to its listed geometry.
CH4
Tetrahedral
NH3
Trigonal pyramidal
H2O
Bent (angular)
BeF2
Linear
BF3
Trigonal planar
Which central-atom hybridization corresponds to approximately 109.5° bond angles?
sp3d with zero lone pairs
sp with zero lone pairs
sp3 with zero lone pairs
sp2 with zero lone pairs
Which combination leads to a trigonal pyramidal shape?
3 bonded atoms and 0 lone pairs
4 bonded atoms and 0 lone pairs
3 bonded atoms and 1 lone pair
2 bonded atoms and 2 lone pairs
Select all molecules that are linear according to VSEPR.
CO2 (as a central-atom example)
BeF2
ClF3
XeF2
SF6
In a trigonal bipyramidal arrangement with no lone pairs, what are the bond angles present?
Less than 105°
90° and 180° only
109.5° only
90°, 120°, and 180°
Which geometry arises from five electron domains with one lone pair on the central atom?
T-shaped
Octahedral
Square planar
Seesaw (distorted trigonal bipyramidal)
Choose all species that have octahedral electron-domain geometry at the central atom.
ClF3
SF6
PCl5
BrF5
XeF4
Which pairing of geometry and example is correct?
Square planar – XeF4
T-shaped – SF4
Seesaw – XeF2
Trigonal bipyramidal – SF6
What hybridization is associated with a central atom that forms two sigma bonds and has no lone pairs?
sp3 with tetrahedral
sp2 with trigonal planar
sp with linear geometry
sp3d with seesaw
Match each geometry to its typical bond angle set.
Tetrahedral
109.5°
Trigonal planar
120°
Octahedral
90° and 180°
Square planar
90° (planar)
T-shaped
90° and 120°
Which statement best defines a molecule in chemistry?
Collection of isotopes of one element
Single atom with full valence shell
Electrically neutral group of bound atoms
Positively charged cluster of ions
Which example represents a molecule composed of the same element?
H2O liquid water
N2 nitrogen gas
NaCl table salt
NH3 ammonia
A molecular compound is best described as a chemical compound whose simplest units are what?
Protons and electrons pairs
Molecules bound by covalent bonds
Atoms with metallic bonding
Ions arranged in a lattice
Which statement about covalent bonds in molecular compounds is correct?
Shared electrons from overlapping orbitals
Transferred electrons between ions
Free electrons in metallic sea
Separated electrons in ionic lattice
According to the octet rule, stable molecules typically have how many electrons in the valence shell?
Ten valence electrons
Twelve valence electrons
Six valence electrons
Eight valence electrons
Which set lists possible covalent bond types found in molecular compounds?
Single, double, triple
Ionic, metallic, hydrogen
Sigma, pi, ionic
Polar, nonpolar, metallic
What structural feature characterizes ionic compounds?
Layers of delocalized electrons
Network of shared electron pairs
Discrete neutral molecules in gas phase
Lattice of alternating positive and negative ions
Which statement about ionic compounds is true regarding electrical conduction?
Conduct only at low temperatures
Never conduct electricity
Conduct well in solid state
Conduct when dissolved in water
Match each term to its description.
Lattice energy
Energy released forming ionic crystal from gaseous ions
Coulomb's Law
Force relation proportional to q1q1 over r squared
Octet rule
Tendency to achieve eight outer electrons
Valence shell
Outer electrons involved in bonding
Which property is typical of ionic compounds when dry?
Highly elastic
Soft and ductile
Hard and brittle
Flexible and malleable
Which chemical formula type shows the relative number of atoms of each element using symbols and subscripts?
Molecular formula
Chemical formula
Formula unit
Empirical formula
Which example is a molecular formula?
CaF2 ionic unit
CH2O simplified ratio
NaCl or KCl
H2O or O3
Which statement correctly describes a formula unit?
Symbol for one atom of an element
Actual numbers of atoms in a molecule
Simplest collection of ions in an ionic compound
Smallest whole-number ratio in a substance
Empirical formulas show what information?
Kinds of atoms and smallest whole-number ratios
Exact count of atoms in a single molecule
Arrangement of atoms in three dimensions
Charge balance within an ionic lattice
Which statements about energy and chemical bonds are correct? Select all that apply.
Endothermic means energy released
Energy is released during bond formation
Bond energy is reported in kJ/mol
Energy is required to break a bond
How does bond length relate to potential energy in a chemical bond?
Energy independent of nucleus distance
Energy proportional to electron mass
Energy inversely proportional to nucleus distance
Energy directly proportional to nucleus distance
Which statement best describes a structural formula?
Shows all valence electrons for each atom
Shows atom types, counts, and arrangement
Shows average bond energy and polarity
Shows only inner-shell electrons in atoms
In Lewis Dot Notation, what do the dots around an element’s symbol represent?
Core electrons in inner shells
Valence electrons available for bonding
Protons and neutrons in the nucleus
Electrons involved only in ionic bonds
Which pair correctly matches bond type with its typical representation in Lewis structures?
Single bond
X–Y or X–Y with one dash
Double bond
X=Y with two shared pairs
Triple bond
X≡Y with three shared pairs
Which statements are true about double and triple bonds?
Triple bonds are even stronger than double bonds
Triple bonds are weaker because electrons are farther apart
Double bonds are stronger than single bonds
Double bonds tend to bend orientation due to electron repulsion
What are lone pairs in Lewis Dot Notation?
Shared pairs between two atoms
Pairs that represent inner-shell electrons
Unshared pairs located only on one atom
Pairs that form ionic bonds between ions
When beginning to write formulas for binary molecular compounds, what is the first step?
Place the least electronegative atom in the center
Assign formal charges to all atoms
Count the total number of valence electrons
Draw all possible resonance structures first
Which guideline helps when drawing a skeleton structure for a molecule?
Put the most electronegative atom in the center
Avoid using single bonds in initial skeletons
Place hydrogen atoms at the center always
Center the least electronegative atom, others arranged around
Which statement distinguishes structural formulas from Lewis Dot Notation?
Lewis notation cannot show bond multiplicity
Structural formulas display all valence electrons
Lewis notation omits lone pairs on atoms
Structural formulas show only bonded electrons
Which statement best explains a resonance structure in molecules like ozone (O3)?
Atoms shift positions to form different isomers
Multiple valid Lewis structures show electron delocalization
Only double bonds move while lone pairs remain
Electrons stay fixed on single bonds only
Which element commonly violates the octet rule by having only two electrons in its valence shell?
Hydrogen with a maximum of two electrons
Helium with eight valence electrons
Lithium with expanded d orbitals
Boron with exactly six electrons
When writing a Lewis structure, what is the next step after placing single bonds between atoms?
Assign resonance hybrids immediately
Give peripheral atoms electrons to complete octets
Move central atom to the highest electronegativity
Add formal charges to each atom
Which pair correctly matches an element with its typical octet-rule exception?
Hydrogen
Two electrons maximum
Boron
Six electrons typical
Helium
Full valence shell of two
Molecules after 3s
Expanded d orbitals allow >8
Select all statements that correctly describe polyatomic ions.
Total group charge written as a superscript on the formula
Charge arises on the whole group due to electron clumping
They cannot form ionic compounds with oppositely charged ions
Groups of atoms bonded covalently with a net charge
Which action can create double or triple bonds when an atom lacks an octet in a Lewis structure?
Remove all single bonds and restart
Move lone pairs into bonding positions
Increase atomic numbers in the formula
Add more central atoms to the molecule
Which statement about expanded octets is accurate?
Expanded octets require ionic bonding exclusively
Only elements before the 3s orbital can expand octets
Atoms with available d orbitals can exceed eight electrons
Central atoms always lose remaining electrons to terminals
What is the key difference between covalent bonds in polyatomic ions and simple molecules?
Polyatomic ions have bonds without shared electrons
Polyatomic ions have covalent bonds but the group carries a charge
Simple molecules always have expanded octets
Simple molecules cannot show resonance
Which formula and charge correctly represent the ammonium ion?
NH4− with −1 charge
NH5+ with +1 charge
NH3− with −1 charge
NH4+ with +1 charge
Which polyatomic ion has the formula SO4 and a −2 overall charge?
Thiosulfate ion, −2 charge
Sulfate ion, −3 charge
Sulfite ion, −1 charge
Sulfate ion, −2 charge
Match each polyatomic ion name to its correct formula.
Phosphate
PO43−
Carbonate
CO32−
Chlorate
ClO3−
Cyanide
CN^−
Which set lists only common polyatomic ions?
Methane, ethanol, propane
Sodium, chloride, calcium
Neon, iron, hydrogen
Ammonium, nitrate, hydroxide
Which statement best describes how polyatomic ions are shown in Lewis structures?
Always drawn with exactly three bonds
Drawn without brackets and no charge
Drawn inside brackets with superscript charge
Shown as single atoms with no bonds
Which ion has the formula NO3−?
Ammonium ion
Nitride ion
Nitrite ion
Nitrate ion
Select all ions that commonly carry a −1 charge.
Hydroxide (OH−)
Cyanide (CN−)
Chlorate (ClO3−)
Ammonium (NH4+)
In the phosphate ion shown, what overall charge is indicated and how is it displayed?
3− charge, outside brackets as superscript
2− charge, inside brackets as subscript
3+ charge, next to phosphorus atom
Neutral, no charge shown anywhere
Which formula-charge pair is correct for carbonate?
CO3^3−, −3 charge
CO4^2−, −2 charge
CO2^−, −1 charge
CO3^2−, −2 charge
Which statement best describes a chemical bond at the atomic level?
External pressure forcing atoms permanently together
Mutual attraction between valence electrons and nuclei
Repulsion between core electrons of neighboring atoms
Random collisions that increase atomic separation
What happens to potential energy when a stable bond forms between two atoms?
Potential energy per atom increases in a bond
Potential energy per atom stays exactly constant
Potential energy per atom oscillates randomly
Potential energy per atom decreases in a bond
Which process requires energy input from the surroundings?
Forming chemical bonds is endothermic
Breaking chemical bonds releases heat
Breaking chemical bonds is endothermic
Forming chemical bonds is always cold
Covalent bonding can produce network solids. Which property is typical of network solids like diamond or quartz?
Ductile metals with shiny luster
Low melting points and softness
Conduct heat poorly and melt easily
Very high melting points and hardness
Which pair correctly distinguishes non-polar and polar molecules in terms of electron distribution?
Both have unequal distribution; differ only in mass
Both have equal distribution; differ only in size
Non-polar unequal distribution; polar equal distribution
Non-polar equal distribution; polar unequal distribution
Electronegativity difference helps predict bond character. Which range most often leads to polar covalent bonds?
Above 3.0 difference always
Between 1.8 and 4.0 exclusively
Approximately 0.3 to 1.7 difference
Exactly zero difference only
Which statement about CO2 and polarity is most accurate?
Bonds are polar but molecule is non-polar linear
Bonds are non-polar and molecule is bent
Bonds are polar and molecule is strongly polar
Bonds are ionic and molecule is tetrahedral
Which statements about polar molecules are correct?
Unequal electron distribution creates dipoles
Asymmetry often leads to overall polarity
Water is a key example of a polar molecule
Negative end is denoted by delta plus
Which statement best describes how an ionic bond forms?
Electrons are swapped so opposite charges attract
Electrons are shared equally between both atoms
Protons are transferred to balance both nuclei
Neutrons move creating temporary attractions
Which property is most characteristic of ionic solids when dry?
Highly malleable and easily shaped
Good conductors of electricity
Hard and brittle crystalline structure
Soft and ductile like wires
Ionic compounds conduct electricity well under which condition?
As solid crystals at room temperature
When dissolved in water as ions move
When cooled to very low temperatures
In powdered form due to friction
According to Coulomb’s Law, what happens to the attractive force between ions when the distance between them increases?
It remains constant for all separations
It decreases with greater separation distance
It increases in direct proportion to distance
It fluctuates randomly with distance
Which factor combination most strongly increases lattice energy magnitude for an ionic compound?
Large ionic charges and large ion sizes
Small ionic charges and large ion sizes
Small ionic charges and small ion sizes
Large ionic charges and small ion sizes
Select ALL correct statements about metallic bonding.
Metals conduct because electrons are highly mobile
Metals are typically malleable and ductile
Metallic bonds require full electron transfer
Electrons are delocalized forming a sea of electrons
Match each bonding type with its key feature.
Ionic bond
Electron swap forming charged ions
Metallic bond
Sea of delocalized electrons
Both ionic and metallic
Attraction due to electrostatic forces
Metals often have few valence electrons. Which observed property is most directly explained by this and electron delocalization?
High luster due to photon emission
Ability to be hammered into thin sheets
Poor electrical conductivity in solids
Formation of brittle crystalline structures
