Chapter 7

• Electron Configurations- P, N, D

  • P= quantum number 1, has a shell shape

  • N variation, Has a few different shapes, has a quantum number of 2, and can have a minimum number of n-1 electrons

  • D orbitals have P and N orbitals within them, have +/- values of the p number, and start on row 3

• Formulas

  • Wavelength formula=

  • Bohr’s equation for energy

  • Bohr’s equation for change in energy

  • DeBoglie Wavelegnths

Chapter 8

• Lewis Structure

  • Developed by Gilbert N. Lewis who proposed that atoms form chemical bonds by sharing electrons to mimic the configuration of a noble gas, which we know today as the configuration filled s and p orbitals in the valence shell of atoms

  • Octet rule for first-row atoms means that all the atoms bonding want to get 8 electrons to fill their valence shell

  • A Lewis Structure is a model of a compound that focuses on the electron pairs in a compound

    • There are bonding pairs, which are chemical bonds within a molecule

    • Lone pairs are pairs of electrons that aren’t bonded

  • Steps for drawing a Lewis Structure

    • Determine the number of valence electrons

    • Arrange the symbols so that you can see how they are arranged and connect them with single bonds

    • Complete the octets of the atoms bonded to the central atom by adding lone pairs of electrons

    • Compare the number of valence electrons in the Lewis structure with the number determined in step 1

    • Complete the octet on the central atom

  • Spare pairs of electrons can be used to form a double or triple bond

• Polar Covalent Bonds

  • Lewis proposed that the sharing of electrons wasn’t even all the time

  • A polar covalent bond is one where the bond is broken, which will result in two ions being formed

  • Bond polarity means that there is a tiny dipole, which is a slightly positive pole, and a slightly negative pole at another end

  • Electronegativity- Charges assigned to a specific element that represents its ability to attract electrons

  • From a difference in electronegativity 0 to 1, the bond is nonpolar covalent

  • From a difference in electronegativity from 1 to 2, the bond is considered polar covalent

  • 2 and up is considered ionic

• Resonance

  • Since there can be many different variations of a Lewis structure, we can draw all of the best possible structures and their variations on the same Lewis structure with dashes representing all the possible bonds

  • Each resonance means that each molecule gets a fraction of a bond

• Formal Charge

  • A formal charge is not a real charge, but a measure of the number of electrons formally assigned to an atom

  • The steps are as follows

    • Determine the number of valence electrons in the atom, usually by the group number

    • Count the number of bonding and nonbonding electrons

    • Count the number of electrons in bonds and divide by two for the number of bonds

  • The preferred formal charge for a compound is zero unless specifies that is an ion

• Exceptions to the octet rule

  • Some molecules can have less than eight valence electrons

  • Free radicals are compounds that have an odd number of electrons and are reactive because they are energetically favorable for them to gain electrons

Chapter 9

• VSEPR theory

  • Molecules are shaped the way they are because of repulsions between electrons and attractions to the central atom

  • Electron-pair geometry defines the relative positions in three-dimensional space of the bonding pairs and lone pairs of valence electrons

  • Molecular geometry depicts the relative positions in three three-dimensional spaces of the atoms in a molecule

  • The steric number of a molecule is determined by taking the number of lone pairs and bonding pairs and adding them together (DOUBLE BONDS COUNT AS ONE AND NOT TWO)

  • Linear, SN=2

  • Trigonal Biplanar, SN=3

  • Tetrahedral, SN=4

  • Trigonal Bipyramidal, SN=5

  • Octahedral, SN=6

  • When SN=4, the axial atoms are bonded to the central atom in a way that resembles the four vertices of a tetrahedron

  • When SN=5 there are different angles, the top bond is 90 degrees, while the rest are 180 degrees and the structure is trigonal bipyramidal

  • Central atoms with no lone pairs

  • When SN=2 in this case, the only shape possible is arranged around the central atom in a bent arrangement, that is a little smaller than 120 degrees because the axial atoms are both attracted to two nuclei and have a large probability of being located between the two atomic centers

• Polar Bonds and Polar Molecules

  • As stated before, differences in electronegativities of elements can cause electrons to be shared unequally

  • The permanent dipole is experimentally measured by measuring the degree to which the molecules align with a strong electronegative between them

  • Dipole moments are expressed in debyes (D), where 1 D is equal to 3.34x10^-30 coulomb-meters

  • In molecules that have many polar bonds around a central atom, the bond dipole may combine to form an overall polarity, which is considered to give the atom a permanent dipole

  • If you look at the model of a CO₂ atom, you will see that it is a linear model that has 180-degree bond angles, and the distribution of electrons makes the overall polarity of the atom 0

  • Other molecules may have polar bonds but are nonpolar because they are symmetrical

  • The water molecule isn’t symmetrical, but the dipoles of the molecule don’t completely cancel out, which gives it a permanent dipole with a positive pole center

• Valence Bond Theory

  • Linus Pauling said that bonds are caused by overlap of an atom’s orbitals, and the more that they overlap, the stronger the bonds would be

  • Valence bond theory arose in the 1930s from Linus Pauling who said that bonds formed from overlap in an atom’s orbitals and the more overlap, the stronger the bonds would be

  • An example would be two hydrogen atoms overlapping bonds produce a single H-H bond, increasing the electron density

  • When a high region of electron density lies along the axis connecting the two nuclei, you end up with a sigma bond

  • To account for different atomic shapes and orbitals, valence bond theory states that atomic energies are mixed through a process called hybridization and form hybrid atomic orbitals

  • To hybridize in a tetrahedral molecule, an electron is promoted to an upper energy level, raising the energy level of an individual atom

  • The three p orbitals balance the gain of energy and now have four carbon orbitals all with equal energy

  • The steric number of an atom always determines the number of its orbitals that need to be filled to hybridize

  • Sp3 orbitals are formed from a molecule that has one s orbital and three p orbitals

  • The four hydrogen atoms in methane can form sigma bonds with the carbon atom

  • Every sp3 orbital contains one major and minor lobe

  • In sp3 hybrid orbitals, sigma bonding between atoms occurs

  • In trigonal planar geometry or sp2 geometry, the energy is lower than an sp3 hybrid and is characterized by having three sigma bonds and a pi bond, which is a bond that overlaps a sigma bond and has the greatest electron density above and below the internuclear axis and can only be formed by the overlap of partially filled p orbitals

  • SP hybrid orbital of acetylene, there is a sigma bonding framework with two sigma bonds that are above and below the molecule

• Shape, Large Molecules, and Molecular Recognition

  • A Lewis structure does well to show all the bonds but doesn't represent the 3d model very well

  • Structures that show all the bonds with lines, but omit lone pairs are known as Kekule Structures

  • Since drawing Lewis structures and Kukele structures can get tedious, chemists use condensed structures to represent individual molecules, which shows the chemical layout, but not the individual bonds

    • Subscripts are used when there are repeated atoms

  • The most minimal notion is the skeletal structure, which has no elemental symbols, and atoms other than C, H, and O are not shown and the structure is drawn in a zig-zag pattern for each corner representing a carbon atom and bond in the middle

    • The angles represent the bond angles of the atoms

  • Molecular structures of many compounds in addition to benzene have carbon rings and delocalized pi electrons above and below the ring and are classified as aromatic compounds

  • Molecular recognition is the interaction between molecules and regions of living tissue that have receptors or active sites

    • They usually require that a biologically active compound fits tightly within the receptor sites

  • Charilaity- Many molecules of daily importance come chilarous, meaning that they aren’t superimposable on a mirror image

Chapter 5

• Collisions and atmospheric pressure

  • The force of each collision of gas particles creates pressure which is the ratio of force to surface area

    • P= F/A

  • The pressure exerted is called atmospheric pressure, anr is measured with a barometer, which is a tool that has a long tube filled with ,ercury and closed at one end and rises and falls base on the atmospheric pressure

  • 1 atmosphere pf [ressure is equal to: 760 mmHg, 760 torr, 101.325 bar

  • The unite of pressure is called the paschal and is 1 kg/ms^2, and is calculated by multiplying the total mass in kilograms by 9.81 meters for the force of gravity and dividing by the displacement in square meters, which is the dimensions squared in meters

• 5.3- The Gas Laws

  • Boyle’s Law- Pressure and Volume law, Z pressure increases, the volume occupied by a gas decreases, and as pressure decreases, the volume increases if the number of moles remains constant

    • Pressure and volume are inversely related, so the formula for Boyle’s Law is P₁V₁=P₂V₂

  • Charle’s Law- The relationship between volume and temperature is linear and if the pressure and number of moles remain constant, the volume of the gas is proportional to the absolute temperature in Kelvin

    • Since Volume and temperature in Kelvin is proportionally related, the formula for Charles’s Law is (V₁/T₁)=(V₂/T₂)

    • Charle’s law also made it possible to determine the temperature of absolute zero in Kelvin, which is equal to -273.15 degrees Celcius

  • Avogadro’s Law- Relats volume and quantity of gasses, as more gas is added to a container, the volume of gas increases, named to honor Amadeo Avogadro, who stated that the volume of a gas is directly proportional to the quantity of gas in moles

    • Since Volume is directly related to the number of moles, the formula of Avogadro’s Law granted pressure and temperature to remain constant is (V₁/n₁)/(V₂/n₂)

      • Not used much in homework, common sense ahh law

  • Amonton’s Law- Relates pressure and temperature when volume remains constant

    • Pressure and temperature are directly proportional to each other, therefore the formula is (P₁/T₁)=(P₂/T₂)

• 5.4- The Ideal Gas Law

  • The ideal gas law combines Charles’s law, Boyle’s Law, Amonton’s Law, and Avogadro’s Law

  • The formula is PV=nRT and is used to find any variable of the formula for a gas at ideal conditions

    • R, the universal constant is 0.0821 (L atm/ mol K) when solving fro pressure in atmospheres and 8.314 for J/(mol K) for Graham’s Law and later equations

  • Combined Gas Law- P₁V₁/T₁= P₂V₂/T₂ is used for finding how pressure and volume affect an object

• 5.5- Gasses in chemical reactions

  • This is using the ideal gas law with stoicheometry to find precise values of gasses produced usually

  • Solve the ideal gas equation for the part specified and then do stoichiometric math on the answer to find the value of the variable that you are solving for

• 5.6- Gas density

  • Gas density can be determined using the formula d= (PM(molar mass))/RT

  • Some gases are denser than others in a container of the same volume

  • Molar mass can be found by using the formula M= (dRT/P)

• 5.7 Dalton’s Law

  • Partial pressure is the pressure of a single gas in a mixture

    • P_total= P₁+P₂+P₃+...

  • Dalton’s Law of Partial Pressures states that the total pressure of any mixture equals the sum of all the partial pressures

  • Mole fractions are used to describe the abundance of each component

    • X_x= (n_x)/n_total

    • N_x is the total number of moles of component x and n_total is the sum of the number of moles of all the components

  • The pressure of a gas is proportional to the quantity if gas in a given volume and deosnt depend on the identity of the gas

• 5.8 Kinetic Molecular Theory of Gasses

  • The kinetic molecular theory of gasses developed in the 19th century explains relationships explained by all of the other theories that came before it

    • Gas molecules have a tiny volume compared with the amount of space that they occupy

    • Gas molecules move randomly and constantly throughout the volume they occupy

    • The motion of the molecules is associated with an average kinetic energy that is proportional to the absolute temperature of the gas. All gas populations have the same average kinetic energies

    • Gas molecules continually collide with each other and with the container walls, and are elastic, meaning that no energy is lost and results in no net transfer of energy

  • Average Kinetic Energy is the average amount of kinetic energy of all atoms in a container

    • Formula is KE_avg= ½ m(u_rms) where u_rms is the root-mean-square speed of a molecule

      • U_rms is formulated by sqrt(3RT/M) where M is the molar mass of the atom

      • The root-means-square is also a measure of the average speed of all of the atoms in a room or container

  • Graham's Law of Effusion- If the walls of a container are semi-permeable, gas will escape at a rate dependent on the speed that an atom is moving at

    • Graham’s Law is determined by taking the u_rms of two elements in a mixture, dividing both of them, seeing that both 3RTs cancel and we are left with r_x/r_y= M_y/M_x

  • Effusion is related to diffusion, which is the spreading of one gas through another

• 5.9- Real gasses

  • Shocker, but most times, gasses aren;t under ideal conditions

  • In reality, gasses don’t behave ideally and they have different behaviors at high pressures because the gas has so much less volume to work with and as a result, becomes more significant

  • The V in the ideal gas law is referred to as free volume because the space isn’t occupied by gas, so instead, the volume of the container is measured

  • Lowering the temperature will also cause deviations in the ideal gas la because the particles are moving slower, resulting in more attraction between the particles in the container

  • The van der Waals equation makes up for these deviations in the situations

    • The free volume of a real gas is less than the total volume because it molecules occupy significant space

    • The observed pressure is less than the pressure of an ideal gas because of intermolecular attractions

  • The van der Waals equation is

  • The values of a and b are called van der Waals constants and they have been determined experimentally for gasses

Chapter 6

• Energy seems like it is negligible since it has no mass or volume, but is ever-present

• Energy cannot be created or destroyed within a system

• The study of energy and its transformations from one form to another is called Thermodynamics

• The part of thermodynamics that desks with changes in energy associated with chemical reactions is known as thermochemistry

• Heat always flows from the cooler object into the colder object

• When no further thermal energy is transferred is when the system has reached a point of thermal equilibrium

• 6.2

  • The energy produced by a chemical reaction can be used to do work, can be transferred to an object to raise its temperature, or both

  • How does hydrogen combusting lead to work being done to raise a spacecraft into orbit

  • The total amount of work done is characterized by the formula w= F x d

  • Potential energy is a form of energy that is determined by an object’s position or composition

    • A skier has a higher potential energy depending on their mass or height above the ground

  • PE= m x g x h

    • This type of potential energy is called gravitational potential because it relates to the pull of gravity on the skier

  • Potential energy is a state function, meaning the it is independent of the pathways followed to acquire the potential energy

  • Kinetic Energy is the total of the potential energies and the sum of his kinetic energies

  • KE= ½ Mu²

  • As the heat of a particle increases, so does its kinetic energy

  • Kinetic energy is associated with the total thermal energy

  • Electrostatic potential energy is the measure of the potential energy between charged particles and the distance between the two of them

    • E_el= (Q₁ x Q₂)/d

• 6.3

  • System- The part of the universe that we are studying

  • Surroundings- Everything else that is not a part of the system

  • An isolated system prevents the transfer of both heat and matter

    • No perfect isolated system exists because even in the best vacuum, energy is still exchanged

  • Closed systems allow the transfer of heat, but not matter

    • Sealed, no-spill travel mug

  • Open systems will enable the transfer of both heat and matter

    • Coffee cup

  • Exothermic reactions are ones where energy flows into the surroundings

    • The quantity q of energy is negative, meaning that energy is released into the system

  • Endothermic reactions are reactions where energy flows from the surroundings into the system

    • Q is positive, meaning that the system absorbs energy

  • The direction of a reversible process will also determine if the sign will change

  • Exothermic processes are deposition, condensation, and solidification

  • Endothermic processes are sublimation, vaporization, and melting or fusion

• In all of these

  • Internal Energy is the sum of all of the kinetic and potential energy of a system

    • Translational- Moving from place to place

    • Rotational- Moving around a fixed axis

    • Vibrational- Movement back and forth

  • All of these depend on the state and mass of the molecule

  • Internal energy change is dE= E_final-E_initial

  • Internal energy is a state function because it depends only on the initial and final conditions and not on the path taken

  • First law of thermodynamics- The energy change of a closed system and it surroundings are equal in magnitude but opposite in sign, so their sum is 0

    • dE_sytem+dE_surrounding=0

  • P-V work- The pressure on a system remains constant but the volume of the system changes

    • The internal energy decreases as is performs P-V work

    • The formula is dE= -q+(-pdV)=q-pdV

    • The negative sign in front of pdV is appropriate because as the system expands, it loses energy as it does work on its surroundings

  • Some units needed to calculate dE are a calorie, which is the amount of energy needed to raise the temperature of 1 gram of water from 14.5 degrees Celsius to 15.5 degrees Celsius, and a Joule, which is 1 calorie=4.184 Joules

• 6.4

  • Enthalpy change (dH) is a measure of the change of energy that flows in and out of a system during chemical reactions or physical systems at a constant pressure

    • Enthalpy changes can be formulated as dH= qp=dE+pdV

    • Thus the change in enthalpy is the change in the internal energy of the system at a constant pressure plus the P-V work being done by the system to its surroundings

  • Enthalpy (H) of a thermodynamic system is the sum of the internal energy and the pressure-volume product

  • Identifying the absolute values of enthalpy is difficult, but identifying the changes in enthalpy is fairly easy

  • According to the equation, the enthalpy change for a reaction run at constant pressure is equal to qp, which is the heat gained or lost by the system during the reaction, meaning that the units of dH are the same as those for q

    • Enthalpy has the units of Joules and is reported to the respect of a quantity of a substance, usually J/g or J/mol

  • dH and dE are ways to represent changes in a state function of a system, but the difference between them is that dE includes all of the energy (heat and work) exchanged by the system and its surroundings and dH is the amount of energy that is exchanged at a constant pressure

  • If the volume stays the same, however, the values of dE and dH are relatively the same

  • If we wish to write the enthalpy change associated with the system, we should write dH_system

• 6.5

  • If hikers prepare a bit of snow for instant soup, the heat from the flame goes into the snow causing the temperature to climb until it reaches a state where all of the snow is melted

  • Once it has all melted, the temperature rises until it reaches 100 Celsius, where it remains stray while the liquid water becomes water vapor

  • Molar heat capacity(c_p) is the quantity of energy required to raise the temperature of 1 mole of a substance by 1 degree Celsius, and the symbol used to represent the capacity is c_p, where the p subscript represents the value for a process taking place at a constant pressure

  • The formula is q= nc_pdT, where n is the number of moles of a substance and dT is the temperature change in degrees Celcius

  • Some tables of thermodynamic state include values of specific heat (c_s) of a substance, which is the amount of energy that is needed to raise the temperature of 1 gram of a substance 1 degree Celcius and has the units J/(gC)

• Molar Enthalpy of fusion (dH_fus)

• 6.6

  • An experimental method of measuring the quantities of energy associated with a chemical reaction and physical changes is known as calorimetry

  • If you wanted to find the specific heat of aluminum, you would follow these steps

    • Find the specific heat of the aluminum ny raising the temperature of the aluminum and then putting it into boiling water

    • Then, insert the heated aluminum into a styrofoam container that is filled with room temperature water and record the temperature change with a thermometer

    • Find the change in temperature or dT

    • The heat gained by the water is equal to the heat lost by the aluminum due to the first law of thermodynamics