Intro to Bonding
What is the difference between intermolecular and intramolecular forces?
Intermolecular forces are between different substances; intramolecular forces are within a substance (chemical bonds).
What is the difference between a polar and nonpolar covalent bond?
Polar covalent: electrons unequally shared (ΔEN > 0). Nonpolar covalent: electrons equally shared (ΔEN = 0).
What does VSEPR stand for and what does the theory predict?
Valence Shell Electron Pair Repulsion — electron pairs arrange as far apart as possible, determining molecular shape.
Rank the three types of intermolecular forces from weakest to strongest.
London dispersion < Dipole-dipole < Hydrogen bonding.
A mystery compound is a crystalline solid, has a high melting point, and conducts electricity when dissolved in water. Is it ionic or covalent?
What is Ionic. Crystalline solid structure, high melting point, and ability to conduct electricity when dissolved are all properties of ionic compounds.
hat does "bonding is a spectrum" mean? Name the two ends.
Bonds range from 100% covalent (ΔEN=0, equal sharing) to 100% ionic (ΔEN>2, electron transfer).
How many electrons are shared in a single bond? A double bond? A triple bond?
2 electrons; Double = 4 electrons; Triple = 6 electrons
What is the molecular geometry of H₂O and how many bonding/lone pairs does oxygen have?
Bent shape. Oxygen has 2 bonding pairs and 2 lone pairs.
What is a hydrogen bond and when does it form?
Forms when H is bonded to N, O, or F and is attracted to a lone pair on an electronegative atom of a nearby molecule.
A bond forms between two atoms with an electronegativity difference of 1.8. What type of bond is it
What is Polar covalent bond
Why do most atoms form chemical bonds?
To become stable — atoms gain, lose, or share electrons to achieve a full outer energy level (octet rule).
Name the compound: N₂O₃
Dinitrogen trioxide
Name the shape for a molecule with 4 electron domains and 0 lone pairs.
Tetrahedral.
How does IMF strength affect boiling point and viscosity?
Stronger IMF = higher boiling point and higher viscosity.
A molecule has 4 electron domains — 2 bonding pairs and 2 lone pairs. Name its shape, state whether it is polar or nonpolar
what is and bent, Polar (asymmetrical)
What does a chemical formula tell you? Give an example.
it tells you which elements are present and how many atoms of each. Ex: H₂O = 2 hydrogen + 1 oxygen.
Write the chemical formula for diphosphorus pentoxide.
P₂O₅
How do lone pairs affect molecular shape?
Lone pairs push bonding pairs closer.
Is CO₂ polar or nonpolar? What IMF acts between CO₂ molecules?
Nonpolar (symmetrical/linear). Only London dispersion forces act between CO₂ molecules.
H₂, N₂, O₂, F₂, Cl₂, Br₂, and I₂ are all examples of this.
What are diatomic molecules?
State the octet rule and its two exceptions.
atoms gain, lose, or share electrons to get 8 valence electrons. Exceptions: Hydrogen (needs 2) and Helium (already stable with 2).
Water (H₂O) is an example of this type of covalent bond because oxygen pulls the shared electrons closer to itself than hydrogen does
What is a polar covalent bond?
Name the shape for: 2 electron domains, 3 electron domains, and 5 electron domains.
2 = Linear; 3 = Trigonal planar; 5 = Trigonal bipyramidal.
Rank from highest to lowest boiling point: CH₄, H₂O, HCl.
H₂O > HCl > CH₄
This is the dominant intermolecular force acting between two polar molecules that do NOT contain hydrogen bonded to nitrogen, oxygen, or fluorine
What is dipole-dipole force