Chem Unit 2 Quizlet

Covalent bond

A bond where electrons are shared between atoms

Lone pair

A pair of valence electrons not used in bonding

Orbital

A region where electrons are found

Nonpolar covalent bond

Electrons are shared equally between atoms

Polar covalent bond

Electrons are shared unequally between atoms

Nonpolar molecule

A molecule with no positive or negative side

Polar molecule

A molecule with partial positive and negative sides

Pressure

Force exerted on an area

Concentration

The amount of solute in a given amount of solution

Dimensional Analysis

A method of analyzing values using units

Dissociation

Separation of ions when an ionic compound dissolves

Molarity (M)

Moles of solute per liter of solution

Solubility

How much solute can dissolve in a solvent

Solute

The substance being dissolved

Solution

A mixture of solute dissolved in solvent

Solvent

The substance that does the dissolving

Acid

A substance that produces H+ ions in solution

Base

A substance that produces OH- ions in solution

Salt

A compound formed from acid-base neutralization

Hydronium (H3O+)

Water molecule bonded to a proton

Hydroxide (OH-)

A negative ion made of oxygen and hydrogen

Strong acid/base

Completely dissociates in water

Weak acid/base

Partially dissociates in water

Amphoteric

Can act as both an acid and a base

VSEPR model

A model used to predict molecular shape by minimizing electron pair repulsion

Linear shape

2 bonded atoms, 0 lone pairs, 180°

Trigonal planar

3 bonded atoms, 0 lone pairs, 120°

Bent shape

2 bonded atoms with lone pairs causing the shape to bend

Tetrahedral shape

4 bonded atoms, 0 lone pairs, 109.5°

Trigonal pyramidal

3 bonded atoms, 1 lone pair

Dipole

A separation of positive and negative charges

Electronegativity difference (ΔEN)

Difference in attraction for electrons between atoms

Nonpolar covalent (<0.5)

Bond with small electronegativity difference

Polar covalent (0.5–1.6)

Bond with moderate electronegativity difference

Ionic (>2.0)

Bond involving transfer of electrons

Valence Bond Theory

Covalent bonds form when atomic orbitals overlap and share electrons

Hybrid orbitals

Orbitals formed by combining atomic orbitals

Sigma (σ) bond

Bond formed by overlapping hybrid orbitals

Pi (π) bond

Bond formed by overlapping p orbitals

Polarity rule

Molecules with asymmetric polar bonds are polar

Symmetrical molecules

If bonds are arranged symmetrically, molecule is nonpolar

Intermolecular forces

Forces of attraction between molecules

Dipole–dipole force

Attraction between positive and negative ends of polar molecules

Hydrogen bond

Strong attraction involving H bonded to N, O, or F

Dipole-induced dipole

Polar molecule induces temporary dipole in nonpolar molecule

London dispersion force

Weak force caused by temporary electron movement

IMF strength effects

Stronger IMFs increase boiling point and surface tension

Cohesion

Attraction between molecules of the same substance

Adhesion

Attraction between different substances

Surface tension

Measure of attraction at a liquid’s surface

Vapor pressure

Tendency of molecules to escape into gas phase

Water density

Most dense at 4°C

Ice density

Ice is less dense than liquid water

Universal solvent

Water dissolves many substances due to polarity

Water polarity

Oxygen is partial negative, hydrogen is partial positive

Dissolving (NaCl)

Oxygen pulls Na+ away, hydrogen pulls Cl- away

Dissolution rate factors

Temperature, surface area, stirring

Temperature effect

Higher temperature increases dissolving rate

Surface area effect

Smaller particles dissolve faster

Stirring effect

Increases rate of dissolution

Solubility rule

Like dissolves like

Polar solutes

Dissolve in polar solvents

Nonpolar solutes

Dissolve in nonpolar solvents

Molarity formula

M = moles ÷ liters

Dilution equation

M1V1 = M2V2

Saturated solution

Cannot dissolve more solute

Unsaturated solution

Can dissolve more solute

Supersaturated solution

Holds more solute than normal

Arrhenius acid

Produces H+ in water

Arrhenius base

Produces OH- in water

Bronsted-Lowry acid

Donates H+

Bronsted-Lowry base

Accepts H+

Binary acids

Naming uses hydro- prefix and -ic suffix

Polyatomic acids

Based on polyatomic ions with added hydrogen

Acid properties

Sour taste, conducts electricity, reacts with metals

Base properties

Bitter, slippery, conducts electricity

pH

A measure of hydronium ion concentration

Strong acid/base

Completely ionizes or dissociates

Weak acid/base

Partially ionizes

Salt formation

Combining anion from acid with cation from base