General Chemistry

One mole of anything contains 6.02 x 10^23 entities. Avagadros # denoted as NA or No. 1 mole of atoms= 6.02x10^23 atoms. Avagadros number is the link between atomic mass unit s and grams. 1 atom of sodium has 23 atomic units (amu=23) = 1 mole of sodium atoms has mass of 23 grams.

#moles= mass in g/ MW How many molecules of N2H4 are in a sample with a mass of 96 grams. So... 96grams/ (32 g/mol) = 3 moles.

Density is mass per volume. kg/m^3. or g/cm^3. waters density is 1g/cm^3.

2 or more atoms form a covalent bond they create a molecule. Molecular formulas tell numbers of atoms in molecule. Empirical formula is the simplest version of molecular formula. So, C6H12O6= CH2O. You can solve formula weight by using chemical formula. Formula weight is the sum of the atomic weights of all the atoms in the molecule. Amu (atomic mass unit) is unit for atomic weight.

If 2 atoms of the same element differ in their numbers of neutrons, then they are called isotopes. The atomic weight of an element is a weighted average of the masses of its naturally occurring isotopes. When a neutral atom gains or loses electrons, it becomes charged, and the resulting atom is called an ion. Each electron gained, atom acquires a charge of -1 unit, and for each electron lost it gets +1. A negatively charged ion is an anion and positively is cation.

64 29 Cu+ mass number is on top; protons/ Atomic number- on bottom. Protons and neutrons in nucleus are held together by force called strong nuclear force. it must overcome electrical repulsion between protons. Unstable nuclei are radioactive and undergo a transformation that make them more stable, altering the number and ratio of protons and neutrons or just lowering their energy. This process is called radioactive decay.

Molarity expresses the concentration of a solution in terms of moles of a solute per volume (in L) of the solution. Moles per liter. concentration is denoted by enclosing the solute in brackets. Mole fraction simply expresses the fraction of moles of a given substance relative to the total moles in a a solution. Its useful way to express concentration when more than one solute is present and used when discussing the composition of a mixture of gases.

A chemical equation is balanced when the number of reactant atoms are equal to the number of products. This illustrates the conservation of mass- (the amount of matter and thus mass, does not change in a chemical reaction. For a balanced equation, the coefficients preceding each compound are known as stoichiometric coefficients. they tell us in what proportion the reactants react and in what proportion the products are formed.

Acid Base Titrations- an experimental technique used to determine the identity of an unknown weak acid (or weak base) by determining its pKa (or pKb). Titrations can be used to determine the concentration of any acid or base solution. Procedure includes adding strong acid (or strong base) of known identity and concentrations -titrant- to solution containing unknown base or acid. Never titrate acid with acid or base with base. Titrant is added in small amounts, pH of solution is recorded.

Add in pic regarding titration curves!

Three types of radioactive decay: alpha, beta and gamma. The nucleus that undergoes radioactive decay is known as the parent, and the resulting more stable nucleus is the daughter. Alpha decay= when a large nucleus wants to become more stable by reducing the number of protons and neutrons, it emits an alpha particle (consist of 2 protons and 2 neutrons). Beta decay= conversion of neutron into proton or vice versa through weak nuclear force.

Alpha decay decreases number of N and P in nucleus. Beta - decay decreases number of neutrons and increases protons- adds 1 to atomic number. Positron Emission- Increases number of neutrons and decreases the number of protons. minus 1 from atomic number Electron capture- increase number of neutrons and decreases protons by 1. Gamma Decay- Brings an excited nucleus to a lower energy state. Doesn't change mass number or atomic number.

Salt bridge- ion rich junction between the anodic and cathodic chambers of an electrochemical cell that prevents charge separation that would otherwise stop the cell from functioning. Anions always migrate toward anode, and cations migrate toward cathode. It maintains electrical neutrality. Prevents the cell from rapidly running to equilibrium. It connects the oxidation and reduction half cells of galvimetric cell.

Anode is always the site of oxidation and cathode is always the site of reduction. Use shorthand notation to identify the species present in a galvanic cell (called cell diagram) Anode /Anodic solution (conc) // Cathodic solution (concentration)/ Cathode Ex. Cd (s) /Cd2+ // Ag+ / Ag (s) **capacitor is a device that stores electrical energy due to separation of charge on adjacent surfaces. Resembles cell with no salt bridge.

Chapter 12: Electrochemistry oxidation number (oxidation state) of each atom in a molecule describes how many electrons its donating or accepting in the overall bonding of a molecule. Many elements can assume different oxidation states depening on the bonds they make. A reaction in which the oxidation numbers of any reactant changes is called oxidation-reduction (redox) reaction. In redox, atoms gain or lose electrons as new bonds are formed. Total number of electrons doesnt change; they just redistributed among the atoms. When atom loses electrons its oxidation number increases (oxidation) and when it gains electrons, oxidation number decreases (reduction) LEO GER- Lose electrons= oxidation; gain electrions= reduction

Atom oxidized in reaction loses electrons to another form. The oxidized atom is the reducing agents or reductant because it is giving up its electrons and causing the reduction of another atom that's gaining the electrons. Atom that gains the electrons has been reduced. the reduced atom is the oxidizing agent because it oxidizes another atom that loses the electrons. Redox reaction can be broken down into a pair of half reactions that show the oxidation and reduction separately. These ion-electron equations show only the actual oxidized or reduced species.

Chapter 5: Bonding and Inter molecular Forces Valence electrons are 1 in first column, 2 then 3 at B, 4 5 6 and 7 for halogens. Lewis dot structures are on type of model used to represent what compounds look like at the molecular level. Valence electrons are responsible for creating bonds in molecules. Lewis dot structures that account for number and location of all valence electrons gives sense of how molecules are held together and helps understand their reactivity.

Calculate formal charge is # valence electrons- 1/2 bonding electrons - lone pairs. Resonance-two or more molecules that accurately depict the bonding in a molecule. Often needed when there are double or triple bonds in molecules alone with one or more lone pairs of electrons. Resonance structures are two or more structures where only non-bonding electrons and double and triple bonds move around.

Bond length is the distance between two nuclei that are bonded to one another. Bond dissociation energy is the energy required to break a bond homolytically (homolytic bond cleavage is where one electron of the bond being broken goes to each fragment of the molecule so H-F become H and F with one electron on each. Heterolytic bond cleavage (dissociation) is where both electrons of the electron pair making up the bond end up on one or the other side resulting in a cation and anion.

Bond order is number of bonds between adjacent atoms, so a single bond has a bond order of 1, double bond has 2 and triple has 3. Higher bond order = shorter and stronger bond. Covalent bonds are formed between atoms when each contributes one or more of its unpaired valence electrons. and they are shared by both atoms to help complete both octets. When a molecule is partially negative and partially positive it is polar. and has a dipole moment.

Standard temperature and Pressure (STP) means temp of 0C or 273.15K and 1atm. Ideal Gas Law relates volume, temp and pressure of an ideal gas. PV=nRT (Pressure, Volume, Moles of gas, gas constant (.0821) and temp in K) Charles law-(volume is proportional to temp. If pressure is constant, then gas expands when heated and contracts when cooled. increased temp, faster molecules

Boyle's Law- If temp is constant, pressure is inversely proportional to volume. (volume decreases, molecules have less space to move around in causing higher pressure.) Avogadro's law- if two equal volume containers hold gas at same pressure and temp, then they contain same number of particles (regardless of identity of gas).

Chapter 11: Acids and Bases Bronsted-Lowry Acids and bases: Acids are proton (H+) donors. Bases are proton acceptors. Lewis acid and bases: Lewis acid electron pair acceptors; lewis bases are electron pair donors. Conjugate Acids and Bases- When a bronsted lowry acid donates an H, the remaining structure is called the conjugate base of the acid.

Bronsted-Lowry acids can be placed into categories of either strong or weak. Their level of strength depends on how completely it ionizes in water. A strong acid dissociates completely in water. HCl is an ex. Weak acid like HF, does not dissociate completely. Ka= [H3O+][A-]/ [HA] this is the acid ionization/ dissociation constant of the acid [HA]. If Ka>1, acid is strong and products are favored. The larger the ka value, the stronger the acid; smaller ka the weaker the acid.

In order for ice to melt, it must absorb heat. to go from liquid to solid, must release heat. When a substance absorbs or releases heat, one of two things happens: Temp changes or it undergoes phase change; not both at same time. Amount of heat absorbed or released by sample is proportional to change in temp. Substances heat capacity (C) is the product of its specific heat (c) and its mass. C=cm. so q= C*Delta T. Specific heat tell how resistant the sample is to changing its temp.

Changing temp is proportional to heat absorbed and inversely proportional to substances heat capacity. As heat is added to the solid, its temperature increases until it reaches its melting point, then the absorbed heat is used to change the phase to liquid, not increase the temp. Once sample has been melted, heat causes the temp to rise and reach BP, then the absorbed heat is used to change the phase to gas, not increase its temp. Once sample vaporized, heat causes temp to rise. During phase transition, the temp of substance does not change. Heat of vaporization is greater than heat of fusion/melting.

Catalysts are formed in one step and consumed in another. If one is consumed but not reformed as a product, then it cannot be the catalyst. rate law tells us that, although a reaction needs all the reactants to proceed, only those that are involved in the rate determining step (slow step) are part of the rate law expression. Rate law: rate= k [A]^x [B]^y; k= rate/ [A][B]^2. Adding a catalyst decreases Ea and increases temperature increases k.

Chapter 10: Equilibrium Ultimately the reaction will come to equilibrium , a state at which both the forward and reverse reactions occur at the same constant rate. At equilibrium, the overall concentration of reactants and products remains the same, but at the molecular level, they are continually inter converting. When a reaction is at equilibrium (And only at equilibrium) the rate of the forward reaction is equal to the rate of the reverse reaction. Equilibria occur for closed systems (no new reactants, products or other changes imposed).

The best reducing agent is the species that has the highest oxidizing potential. If table gives reduction potentials for reagents, you know that its the same as oxidation potential, but with an opposite sign. So if Li has an reduction potential of -3.05 its oxidation potential is +3.05 and makes it the strongest reducing agent.

Chapter 3: Chemistry Fundamentals

Metallic solids: metals. Molecular solids- often liquids or gases at room temp and most likely to be solids as the strength of inter molecular forces increase.

Chapter 6: Thermodynamics Transformation of energy from one form to another. Zeroth Law of Thermodynamics- if 2 systems are both in thermal equilibrium with a third system,then the two initial systems are in thermal equilibrium with one another. First law: Total energy of universe is constant. It can be transferred from one form to another, but not created or destroyed.

Phase of a substance also depends on pressure. The phase diagram of water is unique bc its solid/liquid equilibrium line has a negative slope. this accounts for the fact that ice melts under increased pressure (skater glides over water) and why density of ice is less than that of liquid water.

Chapter 8: Gases (Cubic centimeter= cc) Gas has no fixed volume. It is will all available space in a container. Much more compressible than solids or liquids, and densities are very low (3-4 magnitudes less than liquid or solid). Biggest difference between it and solid or liquid is that gas are free to move over large distances.

Grahams Law of Effusion: states that the ratio of effusion of a gas is inversely proportional to its molecular weight; lighter gases effuse quicker than heavy ones. (Rate of effusion of Gas A/ Rate of effusion of Gas B) = square root of (molar mass of gas B/ Molar mass of gas A) The escape of a gas molecule through a very tiny hole into an evacuated region is called effusion. The rate at which a gas effuses should depend directly on how fast its molecules move; the faster they travel, the more often theyd collide with the hold and escape. Lighter molecules travel faster, because the kinetic energy depends on both mass and speed of molecules (1/2mv^2)

Chapter 9: Kinetics Chemical kinetics is the study of how reactions take place and how fast they occur. Kinetics tells us nothing about the spontaneity of a reaction! Intermediates are necessary for the conversion of reactant to product. Adding up all the reactants and products, the intermediates cancel out. Rate determining step determines the rate of the reaction; the slowest step in a process determines the overall reaction rate.

Buffering region on titration curve is the area where the pH changes very gradually. The point during the drastic pH increase at which just enough NaOH has been added to completely neutralize all of the HF (weak acid with strong base)= acid-base equivalence point. For a weak acid (titrated with strong base), equivalence point with be pH>7. For weak base (titrated with strong acid), equivalence point is pH <7. For a strong acid (titrated with strong base) or vice verse, equivalence point is pH=7

Draw pg 251-253.

The equilibrium constant expression is a ratio: the concentration of the products divided by those of the reactants, each raised to the power equal to its stoichiometric coefficient in the balanced equation. If the reaction is not at equilibrium, the same expression is known simply as the reaction quotient, Q. Q= products/ reactants. The point is now that the concentrations in expression Q do not have to be the concentrations at equilibrium, If they are at equilibrium then Q will = Keq

Comparing Q to Keq tells the direction the reaction will proceed.Reaction wants to be Q=Keq. If Q is less than Keq, it will proceed forward in order to increase the concentrations of the products and decrease the concentration of the reactants in order to increase Q to the Keq value. If Q is greater than Keq, the reaction will be reversed in order to increase the concentration of the reactants and decrease the concentration of the products to reduce Q to Keq.

To describe the voltage of an electrochemical reaction, under nonstandard conditions, use the nearnst equation. E= Potential energy (Eo) - .0592/n x log([B]^b/[A]^a)

Concentration cell is a galvanic cell that has identical electrodes but which has half cells with different ion concentrations. When concentrations of solutions become equal, the reaction will stop. Most redox titrations involve the use of a redox indicator. It uses a change in color to determine the endpoint. This change in color is due to a change in oxidation state (not loss or gain of proton like titration of acid or base) Common redox indicator is Ce4+; bright yellow in solution; reduced Ce3+ is colorless.

2 assumptions of Kinetic-molecular theory: 1) particles of ideal gas experience no inter molecular forces. 2) Volume of individual particles of an ideal gas is negligible compared to volume of containers.

Daltons law of partial pressures says that the total pressure is simply the sum of partial pressures of all the constituent gases. Can determine total pressure if know the partial pressures. or vice versa. Partial pressure of a has is equal to its mole fraction times the total pressure.

To determine whether the redox reaction of a cell is spontaneous and can produce an electric current, need to solve for voltage. Each have reaction has a potential (E) which is the cell voltage. Adding half reaction potentials for a given pair of electrons, we get cells overall voltage. If cell voltage is positive, reaction is spontaneous. If negative, reaction is nonspontaneous.

Delta G o for a redox reaction in which cell voltage Eo is: Delta Go= -nFEo ; F= faraday Always do R - L or Cathode - Anode to find voltage of cell. The more negative the reduction potential, the weaker the reactant is as an oxidizing agent and the stronger the product is as a reducing agent. The more positive the reduction potential, the stronger the reactant is as an oxidizing agent, and the weaker the product is as a reducing gent.

Gibbs Free Energy (Delta G) The magnitude of change in Delta G is the energy that's available (free) to do useful work from a chemical reaction. Spontaneity of reaction determined by changes in enthalpy and in entropy. Delta G= Delta H - T(Delta S) (T is temp in K) Delta G less than 0 (negative) is spontaneous in forward direction. Delta G= 0; reaction at equilibrium Delta G >0 (positive) is non-spontaneous in the forward direction. So if Delta G for reaction is + (non-spon) in the forward direction then Delta g in reverse reaction is same magnitude but negative and therefore spontaneous.

Delta H -, Delta S +, Delta G is then - and spontan. D H+, DS +, DG - with high T and + with low T DH -, DS-, DG + at high T and - at low T DH +, DS - , DG is + and non spontaneous.

3 distinct designations to describe energy flow: System(what you're looking at), surroundings (everything else) and thermodynamic universe (universe) (system and surroundings together form universe). Enthalpy- measure of heat energy released or absorbed when bonds are broken and formed during a reaction that is run at constant pressure. Symbol for enthalpy is H. When a bond is formed, H is released (-delta H) When bond is broken, energy must be put in. delta H is + or >0. Enthalpy change= Delta H is heat of reaction.

Delta H is H products - H reactants If products have stronger bonds than reactants, then more energy is released in making product bonds than breaking reactant bonds. So energy is released from system and its exothermic. Products are in lower energy state than reactants and delta H is negative. Heat flows out of system. If products have weaker bonds than reactants, then more energy is put into breaking the reactant bonds. energy is absorbed overall and reaction is endothermic. Products have higher energy state and delta H is positive since heat is added to the system.

Nuclear binding energy (EB) in eV = delta m(in amu) x c^2 (MeV). c being speed of light. electron volts. The energies of the photons, or particles of light that are emitted, are related to their frequencies and wavelength. Ephoton= hf= h c/lamda. h is plancks constant (6.63 x10-34) and c is speed of light. Bohr model- described new model of atom. proposed that electrons in an atom orbited the nucleus in circular oaths. Distance from the nucleus was related to the energy of the electrons; electrons with greater energy orbited at a greater distance.

Electrons are initially in ground state (n=1)- the lowest possible energy level. When electron absorbs a photon it jumps to a higher energy level known as excited state. A bohr atom is one that contains only one electron. Ex. H+ Positive energy change when absorption occurs. Electron is jumping to higher energy level so the incoming photon is absorbed by the electron. Negative energy change when emission occurs. Electron drops to lower energy level and the electron is emitting a photon.

Hess's law states that if a reaction occurs in several steps, then the sum of the energies absorbed or given off in all the steps will be the same as that for the overall reaction. If a reaction is reversed, the sign of delta H is too. If an equation is multiplied by a coefficient, then delta H must be too. Enthalpy can be seen as energy stored in chemical bonds of a compound. delta H positive means endothermic. Energy is needed to break a bond. Energy is released to make a bond. Delta H of reaction: Sum of bond energy broken minus sum of bond energy formed.

Entropy- disorder of universe. Second law states that the disorder of the universe increases in a spontaneous process. Nature has the tendency to become increasingly disorganized. another way to state second law is that "all processes tend to run in a direction that leads to maximum disorder." Disorder or randomness is measured as Entropy. The greater the disorder of a system, the greater is its entropy. It is represented by the symbol S. change in entropy during a reaction is represented by delta S. Delta S is S product- S reactant.

Metal reacts violently in water to form NaOH and H gas and fire. So if electrolysis of aqueous NaCl occurs, NaOH (aq) and HOCl(aq) more than likely formed because Na(s) will be violent.

Faradays law of Electrolysis- The amount of chemical change is proportional to the amount of electricity that flows through the cell.

1000L = 1m^3 1L = 1000cm ^3 so 1mL =1cm^3 = 1cc Angstrom= unit of length equal to 10^-10. atomic radii and bond lengths are around 1-3A.

How many orders of magnitude is a cm longer than an Angstrom? Order of magnitude= factor of ten. 1cm= 10^-2 and angstrom 10^-10. so 8 orders of magnitude larger.

Electrolytic cells- use external voltage source (battery) to create an electric current that forces nonspontaneous redox reactions to occur. (electrolysis). Electrolytic cell has cathode on R and anode on L. electrons flow from anode to cathode. uses battery. This describes cell phone when recharging battery.

In both galvanic and electrolytic cells, the anode is site of oxidation and cathode is site of reduction. Extrons move from anode to cathode. Difference= galvanic cell uses spontaneous redox reaction to create an electric current where an electrolytic cell uses an electric current to force a nonspontanous redox reaction to occur.

(Instantaneous dipole induced dipole)London dispersion forces are very weak and transient interactions between the instantaneous dipoles in non polar molecules. They are the weakest. Dipole forces, H bonding and London forces are all collectively known as van der waals forces. However, that is usually used to mean only London dispersion forces.

In order for H bond to form, two specific criteria must be fulfilled: 1) molecule must have covalent bond between H and either N, O or F. 2) Another molecule must have a lone pair of electrons on an N, O or F.

Buffer solutions- a buffer is a solution that resists changing pH when a small amount of acid or base is added. (can be used to determine the pH of a buffer solution)Henderson Hasselbach Equation for acid = pH= pka+ log (conj. base/ weak acid) when base and acid are equal, pH=pKa and this is ideal. pOH= pKb + log (Conjugate acid/ weak base)

Indicator is a weak acid that undergoes color change when converted to its conjugate base. It changes color in the rage of + or- 1pH unit from pKa.ooooo If [H3O+] >> Ka, See color 1. If [H3O+] = Ka, see mix of color one and two. If [H3O+] << Ka, see color 2. Phenolphthalien is an indicator with a pKa value of 9. When added to solution whose pH is less than 8, it remains colorless. If solution pH above 10, it will be deep magenta. Methyl orange has pKa of 3.8 so it changes color around pH 4.

Bond is polar if electron density between the two is uneven. partial + and partial -. Non-polar if electron density between the two nuclei is even. Occurs when two atoms of same element are bonded to each other like F2. When atom donates both of the shared electrons in a bond its a coordinate covalent bond. A Lewis base is the molecule that donates a pair of electrons. it acts as the nucelophile (nucleus loving). The molecule that accepts the pair of electrons is the Lewis Acid/ electrophile (electron loving). If coordinate covalent bond breaks, nucleophile takes its electrons with it.

Ionic bonds are held together by electrostatic attractions between a cation and anion. So Na+ and Cl- is an ionic bond. VESPR theory- The shapes of simple molecules are predicted by valence shell electron pair repulsion. This determines the bond angles. One rule: since electrons repel one another, electron pairs attempt to move as far apart as possible. In BeH2, the bonding electrons try and move as far apart as possible so the bond angle is 180 degrees/ Linear shape.

electrons in the outermost shell is valance electrons. Each filled shell between the nucleus and valence electrons shields - protects- the valence electrons from the full effect of the positively charged protons in the nucleus. = nuclear shielding or shielding effect.

On periodic table, acidity increases from top L to bottom R. Electronegativity (and ionization energy) increases from bottom L to Top R. These atoms are more negative electron affinity. Atomic radius increases from Top R to bottom L. Electronegativity(F>O>N=Cl>Br>I>S>C=H) is measure of atoms ability to pull electrons to itself when forming covalent bond.

Vapor Pressure: determined by strength of inter molecular forces of a substance. Its the pressure exerted by the gaseous phase of a liquid that evaporated from the exposed surface of the liquid. weaker the force, the higher its vapor pressure and more easily it evaporates. Easily vaporized liquids are said to be volatile. IM forces are likely to influence melting point, solubility and vapor pressure.

Ionic solids are held together by electrostatic attraction between cations and anions in a lattice structure. Ionic bonds are strong and most ionic substances are solid at room temp (NaCl). Network solids- atoms are connected in a lattice of covalent bonds; all interactions between atoms are covalent bonds. These are very strong and tend to be very hard solids at room temp like diamonds and quartz.

Stoichiometric coefficients give the ratios of the number of molecules (or moles) that apply to the combination of reactants and the formation of products. They do not give ratios by mass. If 108 g of Al are consumed, how many grams of H gas produced? 2Al + 6HCl -> 2 AlCl3 + 3H2 108g Al x (1mol/27g) = 4mol Al x ( 3 mol H2/2mol Al)= 6mol H2 x (2gram/ 1mol H2) = 12g of H2.

Limiting reagent- the reactant that runs out first. it limits how much product the reaction can produce. Phases of the substances in the reaction can be specified- solid (s), liquis (l), gas (g), Aqueous (aq). If reactants are heated to produce the desired reaction a delta symbol is placed over the arrow. Some reactions proceed quicker in the presence of a catalyst (substance that increases the rate of a reaction without being consumed).

sigma bonds are single bonds. so there are sp-sp sigma bonds. pi bonds are double bonds. single bond is composed of one sigma bond. double bond is composed of one sigma and 1 pi. triple bond composed of 1 sigma bond and 2 pi bonds.

Liquids and solids are held together by inter molecular force like dipole dipole forces and London dispersion forces. They are relatively weak interactions that take place between neutral molecules. polar molecules are attracted to ions, making ion-dipole forces Dipole-dipole forces are the attractions between the positive end of one polar molecule and the negative end of another polar molecules. H bonding is strongest dipole-dipole force.

Every electron has two possible spin states (can be considered the elctrons intrinsic magnetism). Because of this every orbital can accommodate a max of 2 electrons, one spin up and one spin down. If an orbital is full, we say that the electrons it holds are spin-paired.

Modern quantum model of atom is represented in electron configuration. Three basic rules: 1) Electrons occupy lowest energy orbitals available. (this is Aufbau principle) The electron subshell's are filled in order of increasing energy. 2) Electrons in the same sub shell occupy available orbitals singly, before pairing up. (Hund's rule) 3) There can be no more than two electrons in any given orbital (Pauli exclusion principle) 1s^2 shows that two electrons fill the 1s subshell.

Different radioactive nuclei decay at different rates. The half life (t1/2) of a radioactive substance is the time it takes for one half of some sample of the substance to decay. So the shorter the half life, the faster the decay. Amount of radioactive substance decreases exponentially with time.

Nucleus containing proton and neutron has nuclear binding energy- the energy that was released when individual nucleons (P and N) were bound together by the strong force to form the nucleus. It is equal to the energy that would be required to break up the intact nucleus into its individual nucleons. The greater the binding energy, the more stable the nucleus. When nucleons bind to form nucleus, mass is converted to energy so mass of combined nucleus is less than sum of the masses of all its nucleons individually. the difference (delta m)- mass defect= total mass of separate nucleons - mass of nucleus. stable nucleus always have + mass defect.

Because a redox reaction involves the transfer of electrons, and the flow of electrons constitutes an electric current that can do work, we can use a spontaneous redox reaction to generate an electric current. A device to do this is called a galvanic (voltaic) cell. Two half cells. Anode and cathode. Salt bridge.

One electrode, composed of a metal (anode) gets oxidized, and the electrons its atoms lose travels along the wire to a second metal electrode (cathode). The cathode is where reduction takes place. Anode acts as an electron source while cathode acts as an electron sink. Electrons flow from anode to cathode. This electron flow is the electric current that is produced by the spontaneous re-dox reaction between the electrodes.

Solids are the most ordered and least energetic of the phases.Molecules of solid are in fixed positions; form orderly array; not enough KE to overcome IM forces. Heating a solid causes kinetic energy to increase loosening the inter molecular interactions and increasing entropy. When enough energy is absorbed for the molecules to move freely around one another it melts to a liquid. Liquids have more internal kinetic energy and greater entropy than solids. Liquids are still in contact and interact with each other, but they have enough K.E. to escape fixed positions. If enough heat is absorbed by the liquid, K.E. increases until the molecules have enough speed to escape inter molecular forces and vaporize into the gas phase. Molecules move freely of one another and experience very few IM forces. Gases are most energetic and least ordered.

Phase changes that bring molecules together (condensation, freezing and deposition) release heat. Phase changes that spread molecules out (melting/fusion, vaporization and sublimation) absorb heat. When matter undergoes phase transition, energy is either absorbed or released. Amount of energy needed to complete transition is heat of transition (delta H) Heat of fusion- amount of heat absorbed needed to change solid to liquid. Heat of vaporization- amount of energy absorbed when liquid goes to gas. Calorie is the amount of heat required to raise temp of 1 gram of water by 1deg C. (q= n*Delta H)

Chapter 7: Phases Matter can undergo physical changes like melting, freezing and boiling. It occurs when inter molecular forces/ bonds are made or broken. Every type of matter experienced inter molecular forces like dispersion, dipole interactions and Hydrogen bonding. The Inter molecular interactions are what hold matter together as solids or liquids.

Physical changes are closely related to temp. Temp is a measure of the amount of internal kinetic energy that molecules have. Kinetic energy of molecules of substance directly affects its state/phase and is also related to the degree of disorder (entropy). Higher K.E. = Higher entropy. Phase changes are the result of breaking or forming inter molecular attractions.

HI, HBr, HCl, HCl04, H2SO4 and HNO3 are strong acids. Kb= [HB+][OH-]/[B]. it is base ionization/dissociation constant. The larger the Kb, the stronger the base. smaller Kb= weaker base. Common Strong bases: Group 1 hydroxides (NaOH), Group 1 oxides (Li2O), Some group 2 hydroxides (Ba(OH)2; Sr and Ca), and metal amides NaNH2. Weak base is NH3 and amines. The conjugate base of a weak acid is a weak base.

Polyprotic- having more than one proton to donate. Water is amphoteric- it reacts with itself in a bronsted lowry acid base reaction, one molecule acts as acid and other as base. Two water reactants makes one H3O+ and one OH- Kw= [H3O+][OH-] and Kw= 1x10^-14 x^2=Kw; x= 1*10^-7 M (concentration of both ions in water is that)

If second step is the slowest, it determines the overall rate of reaction. No matter how fast the first step moves along, the intermediates will pile up in front of the second step as it plods along. The slow reaction dictates the rate of overall reaction. (in chemical reaction the intermediates dont pile up; they shuttle back and forth between reactants and products until the slow step takes it forward. (Rate is always defined as change in something over change in time.)

Rate of a reaction indicates how fast reactants are being consumed or how fast the products are being formed. Reaction rate determined by: how frequently the reactant molecules collide; the orientation of colliding molecules and their energy. Activation Energy (Ea) is the minimum energy required of reactant molecules during a molecular collision in order for the reaction to proceed to products. If the reactant molecules don't possess this much energy, their collisions wont be able to produce the products and the reaction will not occur. If reactants possess the necessary activation energy, they can reach a high energy transition state (the activated complex).

Spontaneous reaction has a negative delta g. nonspontaneous has a positive delta g. If reaction is spontaneous in reverse direction it must be nonsponstaneous in the forward direction. Non spontaneous cell has a negative voltage because cell voltage applies to the forward direction.

Reaction quotient Q, always approaches the equilibrium constant, K, and if Q>K the reaction is pushed in the reverse direction, toward the reactants side of equilibrium, in order to decrease the value of Q. So a reaction of cell spontaneous in reverse reaction, the Q is greater than K.

Argon electron configuration: Atomic #-18. 1s- 2 elec. 2s- 2elec. 2p- 6 electrons. 3s- 2 elec. 3p- 6 electrons. Atom that has all of its electrons spin paired is referred to as diamagnetic(contain even number of electrons). These individual magnetic fields cancel eachother, leaving no net magnetic field. Atom will be repelled by externally produced magnetic field. If electrons are not all spin paired, they are paramagnetic. These atoms are attracted into externally produced magnetic fields.

Row of periodic table is called a period. Column is called family/ group. F- and Ne are isoelectric because when F gains an electron its electron configuration is the same as Ne.

Different ionic compounds will dissociate into different numbers of particles. Some don't dissociate at all, and other break up into several ions. Van't Hoff (ionizability) factor (i) tells how many ions one unit of a substance will make in a solution. i=1 for almost all bio molecules like hormones, proteins and steroids.

Solubility refers to the amount of solute that will saturate a particular solvent. its specific for the type of solute and solvent. It varies with temp. Phase solubility rules: 1) Solubility of solids in liquids tends to increase with increasing temps. 2) The solubility of gases in liquids tends to decrease with increasing temps. 3) The solubility of gases in liquids tends to increase with increasing pressure. Note that as partial pressure increases, the quantity of dissolved gas necessarily increases as the equilibrium constant remains unchanged.

Le Chateliers Principle- states that a system at equilibrium will try to neutralize any imposed change (or stress) in order to reestablish equilibrium. If you add more reactant to a system that is at equilibrium, the system will react by favoring the forward reaction to consume that reactant and reestablish equilibrium. Adding a catalyst to reaction that's already at equilibrium has no effect. (it increases the rate of both the forward and reverse reactions equally, the equilibrium amounts of the species are unchanged. So, introduction of catalyst cause no disturbances. Catalyst increases reaction rate, does not affect the equilibrium.

Solution forms when one substance dissolves into another forming homogeneous mixture. Process of dissolving is known as dissolution. When ionic substances dissolve, they dissociate into ions. Free ions in a solution are called electrolytes because the solution can conduct electricity. Some salts dissociate completely into individual ions, others only partially dissociate. Solutes that dissociate completely (like ionic substances) are called electrolytes and those that remain ion-paired to some extent are called weak electrolytes. Covalent compounds that don't dissociate into ions are non-electrolytes

Percentage composition by mass- molecular or empirical formula can be used to determine the molecules percent mass composition. Ex. C4H4N2. Empirical formula= C2H2N; empirical molecular weight= 40. So %C= 24/40= 60%; %H= 2/40 = 5% and %N= 14/40= 35%. Can work backwards to solve for empirical formula.

Substance is 70% iron and 30% oxygen. So start with 100 grams of the substance. meaning the substance will then contain 70g of Fe and 30g of O. So, solve for number of moles. # moles Fe= 70g/ (55.8g/mol Fe) = 5/4 moles #moles O= 30g / (16 g/mol O)= 15/8 moles Since empirical formula is the ratio of the number of atoms, find the ratio of Fe to O= 5/4mol / 15/8mol= 2/3 mols. So empirical formula is Fe2O3

Each reaction will tend towards its own equilibrium and, for a given temp, will have an equilibrium constant (Keq). Equilibrium expression is (products over reactants)Keq= [C]^c[D]^d/ [A]^a[B]^b this is known as the mass action ratio; the brackets represent the molar concentrations at equilibrium.

The constant k is given subscript to indicate the type of reaction it represents. Ka (for acids), Kb (bases) and Ksp (solubility product)- these are all equilibrium constants. The equilibrium expression is derived from the ratio of concentration of products to reactants at equilibrium. Solids and pure liquids not included in equilibrium because their concentrations do not change. aq substances are included. if reaction gaseous, can use partial pressure of each gas as its concentration. The value of Keq for a given reaction is a constant at a given temp.

Reaction Energy Diagrams- Activation energy- is the extra energy the reactants required to overcome the activation barrier. The higher the barrier, the slower the reaction proceeds to equilibrium. The lower, the faster. Exergonic reaction reactants have higher energy than products. Activation energy is higher. smaller delta G. Endergonic reaction reactants have lower energy than products. activation energy not as large, bigger delta G.

Thermodynamics predicts the spontaneity (and equilibrium) of reactions, not their rates. Kinetics tells you how quickly something happens. Forward reaction and reverse reaction have same magnitude for all values G, H and S. but opposite sign. The reaction energy diagram for reverse reaction can be drawn by using mirror image of forward reaction. Notice that Ea is different for forward and reverse reactions.

Solubility of salts in water: (salt solubility rules) 1) All group 1 and ammonium salts are soluble. 2) all nitrate(NO3-), perchlorate (ClO4-) and acetate (C2H3O2-) salts are soluble. 3) All silver, lead and mercury salts are insoluble, except for their nitrates, perchlorates and acetates.

The extent to which a salt will dissolve in water can be determined from its solubility product constant (Ksp) = products over reactants. Solids are negligible. So Mg(OH)2(s) -> Mg2+ (aq)+ 2OH- (aq) Ksp= [Mg2+][OH-]^2. do ice table. initial. change. equilibrium. it will be 0, x + 2x^2 = 4x^3 Ksp are given in table. so if Ksp=1.6x10-11= 4x^3-4.. x will equal 1.6x10. This means that solution of Mg(OH)2 will be saturated at a Mg(OH)2 concentration of 1.6x10-4M. This method done to determine the salts molar solubility.

Disorder decrease= negative S. Disorder increases= +S Liquids have more entropy than solids. Gases have more than solids or liquids. Particles in solutions have more entropy than undissolved solutions. Two moles of a substance have more entropy than one mole. The value of delta S for a reverse reaction has same magnitude as forward reaction with opposite sign (Delta S reverse= +Delta S forward. Gas undergo condensation= negative Delta H (releasing heat bc goes from gas to liquid) and negative delta S (be decreasing entropy)

Third law of Thermodynamics- defines absolute zero to be a state of zero-entropy. At absolute zero, thermal energy is absent and only the least energetic thermodynamic state is available to the system in question. If only one state is possible, then no randomness to system (S=0). Third law described the least thermally energetic state and lowest achievable temp.

Chapter 4: Atomic Structure and Periodic Trends

The smallest unit of any element is one atom of the element. atoms have a nucleus that contains protons and neutrons (known collectively as nucleons). Electrons are outside the nucleus and they are held in the atom by the electrostatic attraction of the positively charged nucleus. The number of protons in the nucleus is called the atomic number, Z. Protons + Neutrons= Atoms mass number, A.

The ion product is the reaction quotient for a solubility reaction. Qsp < Ksp; more salt can be dissolved. Qsp=Ksp; solution is saturated. Qsp >Ksp; excess salt will precipitate. The common ion effect: The decrease in the solubility of a salt that occurs when the salt is dissolved in a solution that contains another source of one of its ions. Just another form of Le Chateliers principle.

Thermodynamics and Equilibrium: If Delta G is negative, reaction proceeds spontaneoulsy in the forward direction. Delta G o upscript= -RT*lnKeq if its less than , Keq>1 and products are favored at equilibrium. =0; keq=1; products and reactants are present in roughly equal amounts at equilibrium. >0; keq>1; reactants are favored at equilibrium.

total number of electron groups on the central atom of a molecule determines its bond angles and orbital geometry. 2 groups with no lone pair is linear. 3 with no lone pair on central atom is trigonal planar and 4 is tetrahedral. 3 groups with 1 lone pair is bent. 4 groups with 1 is trigonal pyramid. 4 groups with 2 lone pairs is bent.

To determine hybridization for most atoms, add number of attached atoms to number of non-bonding electron pairs. The number of attached atoms plus the number of lone pairs is equal to number of orbitals combined to make new hybridized orbitals. 2= sp and linear. 180 deg. 3= sp^2, 120 degree bond angle and trigonal planar 4= sp^3, 109.5 degrees and tetrahedral. H bonded to anything is just s hybridization.

There are two subshells in the second next highest level (s and p). So oxygen has 8 electrons, 2 are in 1s, then 2 fill 2s and 4 go into 2p subshell (2p^4: 2px^2; 2py^1 2pz^1) P has three circles to fill. all get filled with one going up and then the remaining electrons go down. Atomic number 10 has 10 electrons. So 1s^2, 2s^2, 2p^6

What is the max # of electrons that can go into any s subshell? p? d and f? s subshell has one orientation so only 2 can fill it. p has three orientations so 6. d has 5 possible orientations so 10. f has 7 so 14.

Ex. Add 0.2 mol of HCN (weak acid) to water to create 1 L solution. Find pH? Initially you have HCN=.2M, none of it has dissociated. If x moles of HCN are dissociated at equilibrium, then the equilibrium concentration of HCN is 0.2 -x. Since each molecule dissociates into one H+ ion and one CN- ion, if x moles of HCN has dissociated there will be x moles of H and x moles of CN. So,Ka = products over reactants = [H+][CN-]/[HCN]= x^2/ 0.2-x Ka for HCN is 4.9 x 10^-10 (from table); solve for x= 1*10^-5. x=H+ so pH= -log 1*10^-5= 5

When an acid and a base are combined, they will react in what is called a neutralization reaction. Produces a salt and a water. A salt is an ionic compound, consisting of a cation and an anion. In water, the salt dissociates into ions, and depending on how these ions react with the water, the resulting solution will either be acidic, basic or neutral. Reaction of a substance with water is called a hydrolysis reaction.

1 amu is = 1/12 mass of an atom of carbon (12C) the most abundant naturally occurring form of carbon. Periodic table lists atomic masses of each element, which is actually a weighted average of the atomic masses of all its naturally occurring forms (isotopes) based on relative abundance.

When compound exists as discrete molecules, molecular weight is used instead of formula weight (used for ionic compounds like NaCl).

The lower the activation energy, the faster the reaction rate. The greater the concentrations of the reactants, the faster the reaction rate. The higher the temperature of the reaction mixture, the faster the reaction rate. Catalysts provide reactants with a different route, usually a shortcut, to get to products. A catalyst will almost always make a reaction go faster by either speeding up the rate determining step or providing an optimized route to products. Catalyst accelerates a reaction by lowering the activation energy of rate determining step and therefore the energy of the highest energy transition state is lowered.

difference between catalyst and reactant is that reactants are converted to products, but catalysts remain unchanged at the end of a reaction. it can undergo temporary change but always converted back to original state. Addition of a catalyst affect the rate of reaction, but not equilibrium or thermodynamics of reaction. Catalyst provides different pathway for reactants to get to the products and lower activation energy, it does not change any of the thermodynamic quantities like delta G, H or S. Catalysts decrease the activation energy of the forward and reverse reaction. That's why they have no net effect of a system that's already in equilibrium.

An atoms oxidation state (oxidation number) is meant to indicate how the atoms "ownership" of its valence electrons changes when it forms a compound. Ex: NaCl. The sodium transfers its valence electrons to the chlorine atom, so the sodiums ownership of its valence electrons has changed. So we say that the oxidation state of sodium is now +1 (1 less electron). Chlorine accepts ownership of the electron, so its oxidation state is -1. Giving up ownership results in a positive oxidation state and accepting ownership results in a negative oxidation state.

ionic compounds involve the complete transfer of electrons. The oxidation state of any element in its standard state is 0. So O2 is 0 state. Group 1 metals =+1 state; group 2=+2. Florine=-1. O=-2. KMnO4= (+1)(+7)(-2*4) sum of all oxidation numbers must be 0. Transition metals can assume different states. FeCl2 or FeCl3. either a +2 or +3.

Energy shell (n) of an electron in the quantum model of the atom is analogous to the circular orbits in bohr model. Electron in higher shell has greater amount of energy and greater average distance from nucleus. n=3 (3rd shell) has higher energy than n=2. which has more energy than n=1.

orbital describes a three dimensional region around the nucleus in which the electron is most likely to be found. Subshell in an atom made up of one or more orbitals, denoted by s,p,d or f. that describes shape and energy of orbital. Each shell has one or more subshell, each higher energy shell contains one additional subshell. first energy shell contains s subshell, but second has both s and p.

pH scale measures the concentrations of H+ (or H3O+) ions in a solution. pH= -log [H3O+] or [H+] Solving for the concentration of H+ is done by 10^-pH. low pH= high H+ and solution is acidic. High pH= low H+ and solution is basic. pH>7 basic solution; pH=7 neutral solution; pH<7 acidic solution. pOH= -log [OH-] ; [OH-]= 10^-pOH pH + pOH = 14 If [H+]= 6.2 x 10^-5, you know that pH will be between 4 and 5.

pKa=-log Ka (larger Ka= stronger acid; lower pKa, stronger acid) pKb= -log Kb (lower pKb= stronger base) Ka*Kb=Kw=1*10^-14 pKa + pKb=14 strong acids dissociate completely so the H concentration will be the same as the concentration of the acid. So, in 0.01M solution of HCl, [H+]=.01 and pH= -log.01=2 Weak acids come to equilibrium with their dissociated ions. So for a weak acid at equilibrium the concentration of the undissociated acid will be greater than the concentration of H ions.