AP Chem

Flashcards based on lecture notes for exam preparation.

What is AMU?

A unit to measure small units of mass in Chemistry.

What is the value of unified AMU (u)?

1.660540 x 10^-27 kg

Why is Unified AMU defined as 1.660540 x 10^-27 kg?

For simplicity when thinking of the constituents of an atom or a subatomic particle.

What is the mass of a proton in unified AMU?

1 u

What is the mass of a neutron in unified AMU?

1 u

What is Average Atomic Mass?

A number shown on a periodic table that takes the weighted average of all isotopes.

What is Avogadro’s Number?

6.02214076 x 10^23

What is a mole?

The quantity of substance equal to Avogadro's number.

What are isotopes?

Atoms that have the same number of protons but different numbers of neutrons.

What is relative abundance of an isotope?

Percentage of atoms with a specific atomic mass found in a naturally occurring sample of an element.

What is the calculation for average atomic mass?

Weighted average calculated by multiplying the relative abundances of the element's isotopes by their atomic masses and then summing the products.

What is an empirical formula?

Comes from experimentation. Helps find the ratio of element to element in a molecule

What is a molecular formula?

Helps find the specific quantity of atoms in a molecule.

What is a structural formula?

Gives the structure of a molecule.

What is the empirical formula for water?

H2O

What is the molecular formula for water?

H2O

What are ionic bonds?

Atoms stick together. Opposites attract.

What are covalent bonds?

Atoms share electrons.

What does nonpolar mean in terms of covalent bonds?

No difference in which atom wants more or less electrons.

Why does water form a polar covalent bond?

The Oxygen pulls more of the hydrogens and therefore, a polar covalent bond forms (This is due to the difference in electronegativity values)

What is a metallic bond?

When 2+ metals come together, they form a metallic bond.

What are the properties of metals?

They can conduct electricity, are malleable, and solid at room temperature.

What are the properties of nonmetals?

Cannot conduct electricity, are gaseous at room temperature, etc.

What are noble gases?

Very inert and do not form bonds because they are all stable elements.

How does electronegativity affect bond formation?

High electronegativity will be greedier with the electrons and want more.

What is bond length?

Distance between the atom centers of two diatomic molecules.

How does distance affect potential energy between atoms?

As distance increases between the two atoms, the potential energy increases until it asymptotes at a point where coulomb forces would force the two to have limited interaction with one another

What is a lattice?

Three dimensional structure of ions that have a repeating pattern.

What is lattice energy?

The ability to pull the ions apart from the tightly woven lattice.

What are alloys?

Mixtures of elements that have metallic properties.

What is an interstitial alloy?

An alloy where atoms fit between the small gaps of the other atoms.

What is a substitutional alloy?

Alloys made of similar radius.

What is the octet rule exception?

Many elements can retain more than eight electrons in their outer shell after the third period.

What is resonance?

Multiple Lewis structures for a single compound that are all balanced.

What is formal charge?

(the number of valence electrons in free, neutral atoms) - (# of valence electrons allocated to a bonded atom)

What does VSEPR stand for?

Acronym for valence shell electron-pair repulsion.

What is a dipole moment?

Magnitude of charge x distance between the charges (Qd)

What kind of molecules exhibit London Dispersion forces?

All molecules exhibit London Dispersion forces.

What intermolecular forces are present in nonpolar molecules?

Only intermolecular force present in nonpolar molecules.

How does the number of electrons affect London Dispersion Forces?

More electrons = more polarizable = stronger LDF.

What kind of forces do polar molecules exhibit?

Polar molecules exhibit Dipole-Dipole forces on each other.

What molecules exhibit Hydrogen Bonds?

Any molecule that contains a hydrogen bonded to fluorine, oxygen, or nitrogen exhibits Hydrogen Bonds.

What are Ion-Dipole forces?

Forces can also exist between hydrogen and ions called ion-dipole forces.

What are properties of ionic solids?

High melting point, brittle, conduct electricity when dissolved in water.

What are properties of covalent network solids?

Highest melting point, extremely high hardness, strongest covalent forces.

What are properties of molecular solids?

low melting point, weak intermolecular forces.

What are properties of metallic solids?

Metallic core surrounded by a sea of electrons, excellent conductor.

What is the structure of true solids?

True solids are crystalline in structure.

What are amorphous solids?

Solids that are not completely crystalline.

How do molecules move in a liquid?

Molecules have more freedom of motion.

How do molecules move in a gas?

Molecules can move freely.

What is the Ideal Gas Law?

PV = nRT

What is the universal gas constant(R)?

0.08206 L atm/mol K

What does temperature measure?

Measure of the average kinetic energy of moles in a sample.

What are the properties of ideal gases?

Ideal gases have no intermolecular attractions, and their particles take up no space.

What are heterogeneous mixtures?

Different sections are visible to the naked eye.

What are homogeneous mixtures?

Uniform composition throughout.

How do you calculate solution concentration?

Moles of solute/liters of solution

How does distillation separate solutions?

Takes advantage of the fact that different substances have different boiling points.

How does chromatography separate solutions?

Involves a mixture passing through a column.

What molecules dissolve in polar solvents?

Polar molecules dissolve in polar solvents such as water.

What molecules dissolve in nonpolar solvents?

Nonpolar molecules dissolve in nonpolar solvents.

What does UV/visible light do to molecules?

UV/visible light causes electrons to transition to different energy levels.

What does infrared radiation do to molecules?

Infrared radiation causes molecules to vibrate.

What does microwave radiation do to molecules?

Microwave radiation causes molecules to rotate.

What are the two characteristics of light?

Light can act as a wave and as a packet of light (photon).

What is Beer Lambert Law?

A(absorbance) = E(molar absorptivity) b(path length - width of the cuvette) c(concentration of the solution)

How does electron distribution affect London Dispersion Forces?

Electrons will not always be equally distributed.

What is a dipole?

Separation of charge in two different parts of the atom.

What are London Dispersion Forces?

Attraction of two atoms because of induced dipoles.

What is polarizability?

how easy is it to polarize an electron

How does temperature affect dispersion forces?

Increase in temperature.

How do you describe Molecular dipole moments?

Molecular dipole moments are vector sums of all of the molecular dipoles.

What does a Permanent Dipole describe?

A permanent dipole is attracted to another permanent dipole

How do Hydrogen Bonds form?

Hydrogen is bonded to much more electronegative atoms and it will create a dipole moment from the hydrogen to the more electronegative atom

What are ions?

Atoms that have a net charge

What are dipoles?

Atoms with two different charges

What are physical changes?

Involve change in appearance or state

What are chemical changes?

Transformation of substance

What happens when ionic compounds react in water?

Ionic compounds are completely ionized in water

What are spectator ions?

Ions that do not react

What are the steps in Stoichiometry?

Convert to moles, Mole ratio, Convert to final unit

What are titrations?

Laboratory experiments where we use a buret to slowly add a solution to a flask of a different solution

What does equals equivalence point in titrations?

Moles of base = moles of acid

What is endpoint in titrations?

Moment of color change

What are acid base reactions?

Involve transfer of H+ ion (essentially a proton)

What are redox reactions?

Involve transfer of electrons

What does OIL RIG mean?

Losing electrons is oxidation; gaining electrons is reduction

What is precipitation ions?

Two ions join together to form a solid precipitate

What are Bronsted-Lowry acids and bases?

Acid is a proton donor, base is a proton acceptor

What are Complete Ionic Equations?

Complete Ionic Equations show the individual ions as they are dissociated in water

What does visualizing chemical equations help with?

Helps in understanding the importance of balancing equations and conservation of mass

What is reaction rate?

Rate = change in concentration(mols/liter)/change in time(second)

What are the units of reaction rate?

Molars/second

What factors affect the reaction rate?

Reactant concentration, surface area, temperature, catalyst

What is rate constant (k)?

Constant variable that is only affected by temperature

What is a rate law?

Equation that relates the concentrations of the reactants to the initial rate of reaction

What is the order of reaction based on?

Based on exponents

What is the overall order of the reaction?

Sum of the exponents

What order is a straight line if time is on the x-axis and concentration of reactant is on the y-axis?

Straight line = 0 order