AP Chemistry Unit 3

Type of covalent bond in which electrons are shared unequally is called a (blank)

Polar Covalent bond

Atoms in polar bonds bear (blank). indicated with a lowercase Greek delta and the sign of the charge.

Partial electric charges

A (blank) is a pair of opposite electric charges separated by some distance

Dipole

Polarity is measured as a bond’s (blank)

Dipole moment

More polar bonds have higher (blank)

higher dipole moments

This is a (blank), one where the valence electrons are arranged symmetrically, and no dipole is present.

Nonpolar covalent bond

Molecular polarity also depends on the (blank)

Geometry of the molecule

• Ex: tetra fluoride is highly symmetric that means it is also nonpolar

What types of molecular geometry can be nonpolar?

• Trigonal Planar

• Linear

• square planar

• trigonal bipyramidal

Covalent bonds are bonds between atoms within (blank)

individual molecules

(blank) exists between individual covalent molcules

Intermolecular forces (IMFs)

when polar molecules are close together, a partially positive atom in one will be attracted to a (blank)

partially negative atom in another.

Interactions of permanent dipoles are called (blank)

Dipole-Dipole forces

More polar molecules have larger (blank) and so experience stronger dipole-dipole forces

Charge magnitudes

Hydrogen Bonds are special type of dipole-dipole forces where the hydrogen is the atom that bears (blank)

a partial positive charge in one of the partners

When a hydrogen atoms shares its lone electron, the positively charge nucleus is left bare, this results in (blank)

hydrogen bonds becoming much stronger than dipole-dipole forces

Hydrogen bonds can formed with the three most electronegative

• F

• O

• N

Electron density in molecules can randomly (blank)

fluctuate like a cloud dispersed in the air

Attractions between temporary dipoles are called (blank)

London Dispersion forces

Molecules with more (blank) in them will have a greater chance of forming these temporary dipoles

Electrons

The tendency to distort electron density is called (blank)

Polarizability

All molecules experience (blank)

London Forces

Solids have (blank) IMFs, which hold their shape and volume rigidly

Strong

Gaseous Molecules are (blank) by IMFs

untethered

Liquids have no (blank) but do have (blank)

• Definite shape

• Definite volume

Substances that exhibit only weak IMFs tend to be (blank)

gases at room temperature

Liquid substances tend to have (blank)

stronger IMFs

Ions are (blank)

Metals are (blank)

Nonmetals are (blank)

• Ions held together in a lattice through ionic bonding

• floating in the sea of valence electrons

• secured into network covalent solids by covalent bonds

To melt a substance, enough energy must be put in to (blank)

break the IMFs of the solid state. Referred to as the melting point

IMFs of the liquid state are broken when a substance is heated to its (blank)

boiling point and turns into a gas

(blank) tend to have very high melting and boiling points *name all 3 from lowest to highest

1. ionic substances

2. metals

3. network covalent solids

vapors exert pressure like all gases, which is called the (blank)

vapor pressure of substance

vapor pressure is determined by two main factors

1. IMF strength

2. temperature

Stronger IMFs cause lower (blank)

lower vapor pressures because more energy for molecules with stronger IMFs to escape into the vapor phase

Higher temperatures, where there is more energy to break the IMFs causes (blank)

higher vapor pressure

Boiling point of a substance is the (blank)

temperature necessary to raise its vapor pressure up to the atmospheric pressure

Higher vapor pressure causes a lower (blank)

boiling point

Homogenous mixture is called (blank) and can’t be (blank)

• solution

• differentiated

Heterogenous mixtures can be (blank)

differentiated and retain their original properties

Predict solubility with what rule-of-thumb?

Like dissolves like (meaning matching IMFs)

Polar covalent compounds are similarly soluble in water but they don’t (blank)

dissociate or break in ions like ionic compounds do

Chromatography is used separate different components of a solutions called the (blank) that takes advantage of (blank) in the polarity of molecules

• analyte

• differences

Different types of chromatography

• Paper Chromatography, the pigment that moves up the farthest associates the polarity of the mobile phase

• Column Chromatography, in the eluent (mobile phase) different compounds travel with it and is collected at different fractions then analyzed

The distance any analyze traveled can be expressed by (blank)

Rf = Distance traveled by solute/Distance traveled by solvent

The stronger the attraction between an analyte and the mobile phase, the larger the (blank)

Rf value

Distillation is a common experiment technique used to separate liquid compounds based on (blank)

different boiling points

Gases don’t depend on (blank)

the identity of the molecules

Kinetic Molecular Theory

• Gas molecules are constantly in motions and this exerts pressure

• Gaseous molecules have negligible volume compared to the container they are in

• Gaseous molecules are spread far enough apart and move quickly that IMFs are negligible

• The avg kinetic energy is directly related to the temperature

• if a sample is made of different gases, the particles with have the same average kinetic energy

Gases that fit Kinetic molecular theory are referred to as (blank)

ideal gases

Maxwell-Boltzmann Diagrams Y and X axis

• Y Axis show the number of molecules moving

• X Axis show the molecules at different velocities

As the temperature increase (Maxwell-Boltzmann) the curve changes in two ways

• The curve gets wider

• In short hotter molecules, it moves faster and the peak of the curve decreases

The Ideal Gas Equation

PV = nRT

How do convert Celsius to Kelvin?

add 273

Combined Gas Law

PV/T = PV/T

What relationships are directly related

• Temperature and Pressure (if the volume is constant)

• Temperature and Volume

What relationship is inversely related

• Pressure and volume if the temperature is constant

Dalton’s law states that the total pressure of a mixture of gases is the (blank)

sum of the individual partial pressures

Dalton’s Law equation

Ptotal = Pa + Pb + Pc

Partial Pressure equations

• Pa = Ptotal * Xa

• Xa = moles of gas A / Total moles of Gas

X is expressed as the (blank)

Mole fraction

Two non-ideal things can happen when the gas molecules interact too much

• The volume of the gas molecules becomes significant

• Gas molecules attract one another and still together and the IMFs become significant

Deviations from the Ideal Gas Behavior occur because of (blank)

• High pressures

• low temperatures

Density of a gas equation

• D = M / V

• D = P(molar mass) / RT

Individual packet of light is called a (blank) and it’s energy depends on (blank)

• Photon

• Wavelength and Frequency

Electromagnetic radiation is directly related to (blank) and inversely proportional to its (blank)

• Frequency

• Wavelength

When wavelength is given in nanometer you convert it into to (blank) before using it.

meters

• Ex: 350nm x 1×10^-9 = 3.50 × 10^-7

How to find the energy of a photon when given wavelength?

1. Convert to wavelength to Frequency, (c = yv)

2. Then convert frequency to energy ( E=hv)

How to find the wavelength when given ionization energy

1. convert kj to J by first dividing by avogadro’s number

2. then convert the energy to frequency (E = hv)

3. Then convert it to wavelength (c = Yv)

Beer’s Law measures (blank)

Absorbance

Beer’s Law equation

A = Ebc