Introduction to General Chemistry II

The energy level of electrons gets ______ the further the electrons are from the nucleus. Electrons in _____ shells are at a higher energy level. To understand why, consider the attractive force between the ______ charged electrons and the ______ charged nucleus. Because the force is attractive, ____ (define) is required to separate them; force must be applied over a distance.

In this case, the system is the electron and the nucleus. When an electron is added to a system, ____ is being done, so ____ is being added into the system. This energy shows up as ______ electrostatic potential energy.

The electron configuration of an atom lists the shell s and the subshells of an element's electrons in order from _____ to _____ energy level. After each subshell is a superscript indicating the number of _____ in that subshell.

Electron configurations and noble gas configuration  with for Na, Ar, Fe, and Br

Noble gas configurations for the following ions: Na⁺, Fe³⁺, Br^-, and Be_{with an excited electron}

Define Hund's rule

To understand Hund's rule, consider that like charges _____ each other. If we considered the energy of two particles with like charges, we would find that as the particles approach each other, the mutual repulsion creates an ______ in potential energy. This is the case when electrons approach each other, so electrons avoid sharing an _____ when possible, spreading out amongst the orbitals of a given subshell to minimize _____ _____.

Figure 1.11 depicts Hund's rule for the first eight elements. ______ are represented by vertical arrows, with upward arrows representing ______ spin and downward arrows representing _____ spin. In the configuration for carbon, the second p electron could share the 2px orbital or take the 2py orbital for itself. According to Hund's rule, the electron prefers to have its own orbital when such an ______ is available at the same energy level, so it will occupy the 2py orbital.

Define Paramagnetic elements
The spin of each unpaired electron is _____ to the others. As a result, the electrons will align with an ______ magnetic field.

Define Diamagnetic elements
They are ______ to an external magnetic field

When excited electrons fall from a higher energy state to a lower energy state, energy is _____. This energy creates an _____ _____ _____ that is characteristic of the given element. An _____ _____ _____ measures the radiation absorbed when electrons absorb energy to move to a higher energy state.

Max Planck, the father of quantum mechanics, proposed a theory to explain this phenomenon. He theorized that electromagnetic energy is quantized, that it comes only in _____ units related to the wave frequency. If energy is transferred from one point to another via an _______ wave, and we wish to increase the amount of energy transferred, the energy can only change in ______ _______ given by:
ΔE=hf
What does "h" and "f" signify?

Einstein showed that if light is considered as a particle phenomenon, where each photon is _____ particle, the energy of a single photon is given by the same equation: ΔEphoton = hf

Neils Bohr applied the quantized energy theory to create the Bohr model, where electrons rotate around the nucleus on a path characterized by a certain energy level (shell). His model explained the line spectra for hydrogen but failed for atoms with more than one _____. Louis de Broglie expanded the model to demonstrate the wave characteristics of ______and other moving masses with this equation:
λ=hmv
What does the "h" "m" and "v" signify?

Atoms have both particle and wave properties; therefore atomic structure cannot be understood by considering electrons only as moving particles. The possible energy levels of an electron can be represented as an energy ladder, in which each energy level is analogous to a rung on a ladder. The electrons can occupy any rung but cannot occupy the space between rungs (why?)

When an electron falls from a higher energy rung to a lower energy rung, energy is released from the atom in the form of a _____. The _____ has a wave frequency which corresponds to the _____ in energy of the electron as per the equation ΔE = hf The reverse is also ____. When a photon collides with an electron, it can only _____ that electron to another energy level if its energy corresponds to the energy ______ between rungs. What happens if the photon does not have the exact amount of energy needed to bump the electron to a higher rung?

With the photoelectric effect Einstein demonstrated the existence of a ____to___, _____to____ collision. He used the one-to-one collision to prove that light is made up of ______. Einstein's reasoning went as follows: Light shining on a metal may cause the emission of ______ (sometimes called _______ in the context of the photoelectric effect).

Since the energy of a wave is proportional to its ______, one might expect that when the intensity of light shining on a metal is increased by increasing the number of photons, the kinetic energy of an emitted electron would increase accordingly. This is ______. What actually happens?

If the frequency is less than the necessary quantum of energy, no _____ at all will be emitted regardless of the  number of _____. This demonstrates that the electrons must be ejected by ____-to-____ photon-electron collisions rather than by the combined energies of two or more _____. It also shows that if a single photon does not have sufficient energy, no _____ will be emitted.

Define the work function (Φ) of a metal

The kinetic energy of the ejected electron is given by the energy of the ____ minus the ____ _____.

The characteristics of elements determine the types of bonds that they are likely to form. This section describes the major types of bonds: covalent and ionic (describe THE defining characteristic for both)

A covalent bond is formed between two atoms when their nuclei share a pair of electrons. 1)Atoms held together by only covalent bonds form a _____. 2)Covalent bonds are also known as _______ bonds (i.e. bonds within molecules). 3)Covalent bonds are formed only between ______ elements, and are the predominant type ofbond discussed in organic chemistry.

The negatively charged electrons are pulled toward both positively charged nuclei by electrostatic forces. This 'tug of war' between the nuclei for the electrons holds the _____ together. If the nuclei come too close to each other, the positively charged nuclei _____ each other. These attractive and repulsive forces achieve a balance to create a _____. Figure 1.14 shows how changes in the internuclear distance between two hydrogen atoms changes their _______ ______ energy level as a system.

Two atoms will only form a bond if they can lower their overall energy level by doing so, since nature seeks the _____ _____ _____ state. For this reason, energy is ______ when bonds are formed. Bond length is the distance between the _____ of two atoms in a bond when they are at their ______ _____ _____ state.

If atoms are separated by an infinite distance, the forces between them, and thus the energy of the bond, go to ____. The energy necessary for a complete separation of the bond is given by the ______ distance on the graph between the energy at the bond length and zero. This is called the _____ _____ _____ or _____ _____. (These concepts are closely related and differ only in their sign.)

When electrons are shared equally by two atoms with equivalent electronegativities, it is a _____ _____ bond. When the electrons are not shared equally because of a difference in electronegativity, it is a _____ _____ bond. If the difference in electronegativity is significant, the bond is said to have _____ _____ character. When the electronegativities of the two atoms differ vastly, the bond is _____, meaning that one or more ______ are actually transferred from one _____ to the other.

Ionic bonds occur most often between _____ and _____. Ionic compounds, or salts, can be thought of as _____ charged ions held together by ______ forces. Molecular and ionic compounds differ in that molecules make up separate, ______ units that can be isolated. By contrast, individual ionic bonds are part of a larger ______ structure within a compound and cannot be _____.

Just as atoms interact with each other according to their individual characteristics to form _______ covalent bonds, molecules interact with each other through _______ forces. Intermolecular forces are much _____ than intramolecular bonds, but they are similarly influenced by ______ and _______.

When does a dipole moment occur?

The concept of center of charge is analogous to the concept of center of mass. When the center of positive charge is displaced from the center of negative charge, the bond is said to have a _____ _____ character on one side and a _____ _____ character on the other.

In chemistry a dipole moment is represented by a vector pointing from the center of ______ charge to the center of ______ charge. The arrow is crossed at the center of positive charge, creating a plus sign. The dipole moment is measured in units of ______ (__) and given by the equation:
μ = qd
What do "q" and "d" signify?

A bond that has a dipole moment is _____; a bond without a dipole moment is ______. A molecule with polar bonds may or may not have a net _____ _____. Since a dipole moment is a vector, the sum of the dipole moments of the polar bonds of a molecule can equal _____, leaving the molecule without a ______ _____, as is the case for symmetrical molecules.

Intermolecular attractions (define) occur due to ______ ______. The _____ ____ charge of one molecule is attracted to the partial _____ _____ of another molecule. Intermolecular dipole attractions are _____ electrostatic bonds, generally about 1% as strong as _____ bonds. The attraction between two molecules is roughly proportional to the magnitude of their _____ ______; the stronger the dipole, the _____ the attraction

The strongest type of dipole-dipole interaction is a ______ _____ (when does it occur).

Fluorine, oxygen, and nitrogen are _____ electronegative; when bound to hydrogen, a large _____ _____ is formed, leaving hydrogen with a strong _____ ______ charge. Hydrogen bonding is responsible for the high _____ ____ of water. Though this is the ______ type of intermolecular force, it is still much ____ than any covalent bond.

When does an induced dipole occur?

The partial or full charge of the polar molecule or ion attracts or repels the electrons of the _____ molecule, separating the centers of positive and negative charge. Induced dipoles are ______ in nature and are generally ______ than permanent dipoles.

An instantaneous dipole moment can arise ________ in an otherwise nonpolar molecule. How?

Although instantaneous dipoles are ____-lived and ____, they can create an _____ _____ in a neighboring molecule.

The weakest dipole-dipole force is between two ______ _____. These dipole dipole bonds are called ______ _____ forces or _______ ______ _____ forces. All molecules exhibit ______ _______ forces, even when they are capable of stronger _______ interactions.

The intermolecular forces described in this section apply to _____ just as they do to _____. Molecular crystals, such as ice, are composed of individual molecules held together by intermolecular bonds. Intermolecular forces are generally _______ in gases (why?)

Ionic compounds are named after their ____ and _____. If the cation is transition metal capable of having different charges, its name is followed by a Roman numeral in parentheses indicating the _____. Copper can take on a charge of 1 + or 2+, and is thus designated copper(__) ion or copper(__) ion.

An older method for naming cations adds "-___" to tHe cation with the smaller charge, and "-__" to the ending of the cation with the greater positive charge. With copper this would be _____ for Cu+ and _____ for Cu2+ If the cation is made from a nonmetal, the cation name ends in -___, as is the case for the polyatomic ion ammonium (NH4+). Important ions for the MCAT® are listed in the Solutions lecture.

Monatomic anions and simple polyatomic anions are given the suffix "-___," such as ______ (H-) or ______ (OH-). Polyatomic anions with multiple oxygens end with the suffix "-___" or "-___," depending on the relative number of oxygens. The more oxygenated species will use "-___", such as ______ ion (NO2- ) versus _____ ion (NO3-).

If there are more possibilities, the prefixes "____-" and "____-" are used to indicate the fewest and most oxygens, respectively, such as ________ (ClO-), _____ (ClO2-), _______ (ClO3-), and _______ (ClO4-). If an oxyanion has a ______, the word hydrogen is added, as in _______ ______ ion (HCO3- ). The old name for this ion is _______.

To name an ionic compound, put the _____ name in front of the anion name, as in _____ _____ (BaS04) or _____ _____ (NaH). For binary molecular compounds (compounds with only two elements), the name begins with the name of the element that is farthest to the _____ and _____ in the periodic table. The name of the second element is given the suffix "-___" and a ______ prefix is used for each element with more than one atom (e.g., ______ ______, N2O4).

Acids are named for their _____. If the anion ends in "-ide," the acid name starts with "____-" and ends in "-___," as in ________ acid (H2S). With an oxyacid, the ending "-___" is used for the species with more oxygens and "-___" for the species with fewer oxygens, as in _____ acid (H2SO4) and ______ acid (H2SO3).

Familiarity with commonly used units and the prefixes used to denote the magnitudes of those units is necessary for success in chemistry problems on the MCAT®. By international agreement, SI units are used for scientific measurements. "SI Units" stands for Systeme International d'Unites. SI units predominate on the MCAT®. The seven base units in the SI system are listed in the table below:

Other SI units can be derived from these seven, such as the newton: 1 N = ______. There are other units still commonly in use that may also appear on the MCAT®, such as atm or torr for pressure. **All such units will have an SI counterpart that you should know. These will be pointed out as new units are introduced. 

The SI system also employs standard prefixes for each unit. These prefixes are commonly seen on the MCAT®. Table 1.4 lists these standard prefixes:

When determining the quantities of products and reactants in chemical reactions, it is necessary to know the relative amounts of the ______ in each molecule. A compound is a substance made from ____ or more elements in _____ proportions. Define the empirical formula of a compound

All ionic compounds are represented by their _____ _____. The molecular formula is more commonly used for ______ ______, and represents the exact number of _____ ____ in each molecule. The molecular formula of glucose is ______ , while the empirical formula, or smallest whole number ratio, is _____.

The ______ _____ and the _____ _____ of each element can be used to calculate the percent composition by mass for a compound. How do you find percent composition?

How do you find the empirical formula from the percent composition by mass?

If a compound undergoes a reaction and maintains its molecular structure (and thus its identity), the reaction is called a _____ reaction. State 4 examples of physical reactions.

When a compound undergoes a reaction and changes its bonding or structure to form a new compound, the reaction is called a ______ reaction. ______, ______ and ______ are examples of chemical reactions.

Chemical reactions are represented by chemical equations, with the _______ on the left and the ______ on the right, as in the example below:
CH₄ + 2O₂ ⇌ CO₂ + 2H₂O

O2 and H2O are preceded by a coefficient of ____. If a molecule has no coefficient, a coefficient of ____ is assumed. Here, methane has a coefficient of ____. These coefficients indicate the relative number of _____ molecules or _____ of molecules involved in the reaction. They do not represent the mass, the number of grams, or or the number of kilograms.

How to find the total number of atoms of an element?

Notice that there is a ______ of atoms from the left to the right side of the equation. In other words, there is the same number of oxygen, hydrogen, and carbon atoms on the right as on the left. This means the equation is ______. On the MCAT®, if the answer is given in equation form, the correct answer will be a _______ equation unless specifically indicated to the contrary.

Chemical reactions are categorized into types. Name four important reaction types to know for the MCAT®, write them in their standard form with hypothetical molecules A, B, C, and D, use match them with the real examples.

1)Fe(s) + S(s) → FeS(s)

2)2Ag20 (s) → 4Ag(s) + 0 2(g)

3)Mg(s) + 2HCl(aq) →  MgC12(aq) + Hz(g)

4)HCl(aq) + NaOH(aq) → NaCl(aq) + H 20(l)

Some other important reaction types are redox, combustion, Bronsted-Lowry acid base, and Lewis acid-base, as shown in Table 1.5. These types will be covered later in this manual. Reaction types are not mutually exclusive, so a single reaction can be classified as more than one type.

A standardized set of conventions for writing chemical equations are used to indicate certain characteristics of the chemical reaction, products, and/ or reactants. The symbol 'Δ' usually means "change in," but 'Δ' above or below a reaction arrow indicates that heat is added . When a chemical formula is written above the reaction arrow, it usually indicates a ______. Two arrows pointing in opposite directions ('⇌') indicate a reaction exists in ______ with the reverse reaction.

If one arrow is longer than the other, the equilibrium favors the side to which the long arrow points. A single arrow pointing in both directions ('↔') indicates ______ structures. Square brackets [ ] around an atom, molecule, or ion indicate ______. The naught symbol '°' indicates _______ _____ conditions, as discussed in the Thermodynamics Lecture.

To say that a reaction runs to completion means that it generates _____ until the supply of at least one _____ is fully depleted. When do other reactions reach equilibrium?

Consider this chemical reaction:
CH₄ + 2O₂ ⇌ CO₂ + 2H₂O

The equation shows that two moles of oxygen (O2) are needed to burn one mole of methane (CH4); think of this as a ___ ratio. If the reaction began with four moles of methane and six moles of oxygen, and the reaction ran to completion, ____ mole of methane would be left over. This is called a reactant in _____. From the two-to one ratio in the equation, six moles of oxygen would only be enough to burn _____ moles of methane. Since oxygen would run out first, oxygen is the _____ _____.

How do you know which will be the limiting reactant?
CH4 + 2O2 ⇌ CO2 + 2H2O

The limiting reactant is not necessarily the reactant of which there is the least; it is the
reactant that would be ______ _____ ____ if the reaction were to run to completion. Looking at the products, the one-to-one ratio of methane to carbon dioxide and the two-to-one ratio of methane to water show that burning ____ moles of methane produces three moles of carbon dioxide and ____ moles of water.

Define Theoretical Yield
Define Actual Yield 
Define Percent Yield

Stoichiometry involves figuring out the quantities of ______ and ______ in a chemical equation. Stoichiometry problems on the MCAT® will represent quantities in units of grams, atomic mass units (amu), and moles.

The atomic weight of an atom is generally given in ____. Atomic weight is actually a _____, not a weight. Carbon-12 is used to define the atomic mass unit, with the atomic weight of 1 atom of 12C equal to ___ amu. By this standard, one proton or neutron has a mass of approximately __amu.

The mass of an individual atom is a ____ number expressed in amu, and represents the total number of _____ and _____ in that atom. Why do the atomic weights listed on the periodic table contain decimals?

The atomic weight of carbon is listed as 12.011 amu, which is very close to 12 amu because almost 99% of carbon in nature is ___.

Since atoms and molecules are so small, it is often easier to think of a "bunch" of atoms or molecules, or a mole (define)

¹²C serves as the standard for this as well; Avogadro's number is equal to the number of _____ atoms in 12 grams of ¹²C. Atomic weights can be read from the periodic table as either ____ or ____. Remember the relationship between amu and grams for the MCAT®:
6.022 x 10²³ amu = __ gram(s)

When dealing with multiple elements or compounds, _____ are the preferred unit because they provide a common standard. How do you find the number of moles if the amount of an element or compound in a sample is given in grams?

How do you determine mass when given moles?