Chem Exam (3) PDF - Structure and Properties

Unit 1 - Structure and Properties Key Terms: Quantum numbers- n - principle quantum number, main shell of electrons l - Secondary Quantum number, the shape of the electron orbit, used to describe additional electron sub-levels The number of values for l = the number of principal quantum numbers if...

Unit 1 - Structure and Properties Key Terms: Quantum numbers- n - principle quantum number, main shell of electrons l - Secondary Quantum number, the shape of the electron orbit, used to describe additional electron sub-levels The number of values for l = the number of principal quantum numbers if the principal quantum number is n = 3 there are three sublevels, l = 0,1,2 m - Magnetic Quantum number, relates to the direction of the electron orbit, the number of lines observed in the Spectra determines this For each value of l, m and can vary from -1 to +1 If l = 2 , m can = 2,1,0,-1,-2 Spin quantum number - accounts for additional line splitting in different types of magnetism. Bond Dipole- The partial charges are assigned to bonded atoms due to differences in electron density caused by electronegativity, inductive effects, and other factors. Polar molecules – polar bonds do not mean that you have a polar molecule, using an arrow we show bond polarity from the positive to the negative the arrow represents a bond dipole. The arrows are vectors that add up to zero, the bond dipoles cancel each other out which means there is no polarity for the molecule. Both the shape of the molecule and the polarity of the bonds are necessary to determine if a molecule is polar or non-polar In all symmetrical molecules, the sum of the bond dipoles equals zero meaning that you have a non-polar molecule. Covalent bonds- Even Sharing of Electrons The greater the difference the more polarity, no difference in electronegativity = covalent bond Metallic bonds- created when metal atoms lose their outermost electron to form positively charged ions. Ionic bonds- two atoms exchange electrons to create a positive and negative ion Dipole-Dipole Forces- Caused by an attraction between polar molecule The strength of the force is dependent on the polarity of the molecules The greater the polarity of the individual molecules the greater the forces between them London Forces – the simultaneous attraction of an electron of one molecule with a nuclei of an adjacent molecule The strength of the forces is directly related to the number of electrons in the molecule meaning the greater the number of electrons the stronger the London Forces. Hydrogen bonding- the attraction of Hydrogen atoms (that are bonded to N, O, or F) to a lone pair of electrons of N, O and F atoms in an adjacent molecule. H is bonded to a more electronegative atom which leaves H with a partial positive charge, the slightly +ve. Intermolecular Forces- The stronger the intermolecular forces the higher the boiling points Non-Polar Bonds- When two atoms with the same or very similar electronegativity values share electrons equally. The difference of electronegativity is from 0-0.49 the bond is non-polar Non-Polar Molecule- A nonpolar molecule is a molecule where the overall distribution of electric charge is symmetrical, resulting in no permanent dipole moment. This happens when the molecule's atoms share electrons evenly or the molecular structure is such that any individual bond dipoles cancel each other out. Occurs if all the bonds are non-polar in the molecule or if the shape of the molecule is symmetrical, no matter if there is polar or non polar bonds Polar Bonds- A polar bond occurs when two atoms with different electronegativities form a covalent bond, and the electrons are not shared equally between them. The atom with the higher electronegativity attracts the shared electrons more strongly, resulting in a partial negative charge (δ-) on that atom, while the other atom develops a partial positive charge (δ+) The electronegativity range for polar bonds is 0.5-1.69 Polar Molecule- A polar molecule is a molecule that has an uneven distribution of electron density, resulting in a permanent dipole moment. This means that one part of the molecule is slightly negative, while another part is slightly positive. Occurs when there is a significant electronegativity difference between the atoms involved in the bonds or the molecular geometry is asymmetrical, so the dipoles (the partial positive and negative charges) do not cancel each other out. Polar Covalent Bonds- A polar covalent bond is a type of chemical bond in which two atoms share electrons unequally due to a difference in their electronegativity values. VSEPR- Valence Shell Electron Pair Repulsion pairs of electrons in a valence shell stay as far apart as possible to minimize the repulsion of their negative charges Valence electrons are the only ones important for determining molecular shape Shape Bonding Pair Degrees Linear 2 BP 0 LP 180 Linear 1 BP 3 LP 180 Bent 2 BP 2LP 104.5 Trigonal Planer 3BP 120 Trigonal Pyramidal 3BP 1LP 107.3 Tetrahedral 4BP 109.5 Octahedral 6BP 90 Tri Bypyramdal 120 / 90 Practice Questions: 1- Determine the maximum number of electrons with these principal quantum numbers a)​ 1 = 2 b)​ 2 = 8 c)​ 3 = 18 d)​ 4 = 32 2 2n = total number of electrons allowed 2- How many quantum numbers does it take to fully describe an electron in an atom? Provide and example, listing labels and values of each quantum number 4 quantum numbers are required. These include the n,l,m1, and ms n= determines the energy level or shell of the electron, describes the size of the orbital.(main energy level l= sublevel e belong to (orbitial type) m1 = how many / # of each orbital existing ms = max of 2e- per orbital 3- Electron Configuration Drawings Complete Ground State?? 4- Use VSEPR theory to predict the geometry of a molecule of each of the following substances 1)​ BeI2 - Linear 2)​ PF3 - Trigonal Pyramidal 3)​ H2S - Bent 4)​ BBr3 - Trigonal Planner 5)​ SiBr4 - Tetrahedral 6)​ HCl - Linear 7)​ PO4-3 - Tetrahedral 8)​ IO3- - Trigonal Pyramidal 5- Based upon intermolecular forces, predict which substances in the following pairs has the higher boiling point. Provide your reasoning (a)​ beryllium fluoride or oxygen difluoride Ionic bonds (b)​chloromethane or ethane Dipole - dipole bonding (c) water or hydrogen sulfid Hydrogen bonding Unit 2 - Organic Chemistry Key Terms: Addition reaction - Alcohol - classified based on the number of carbon atoms directly attached to the carbon atom bearing the hydroxyl (-OH) group Aldehyde - compounds that contain a carbonyl group (C=O) bonded to at least one hydrogen atom. Carbonyl group is on terminal carbon Alkane - CnH2n+2 Has an ane ending to the hydrocarbon chain. Has C-C Alkene - CnH2n-2 ene ending. Has a C=C Alkyl group - An alkyl group is a group of atoms derived from an alkane by removing one hydrogen atom. yl ending Alkyl halide - contain halide functional group. containing one or more halogen atoms (F,Cl,Br,I) bonded to an alkyl group. Determine the longest hydrocarbon chain and then the position of the halid. Fluoro, chloro, bromo, iodo infront of hydrocarbon. Add prefix depending on amount of halides. Alkyne - CnH2n Has yne ending. C triple bond C Amide - Amine + Carboxlyic Acid seperated by C-N to determine the 2 parts from eachother Amine - Presents of a N attached to either 2 hydrogens 1 carbon chain (primary), 1 hydrogen 2 carbon chains (secondary) or 3 separate carbon chains (tertiary) Primary had amide ending Secondary Take shorter carbon chain and add N-alkly Tertiary Take 2 shortest carbon chain and add N-alkly Phenol - If the -OH group is directly bonded to a benzene ring in an alcohol Aromatic hydrocarbon - An aromatic hydrocarbon is an organic compound containing one or more benzene rings or other planar cyclic structures.These rings have alternating single and double bonds, creating a stable system of electrons called a conjugated system. To be aromatic, the compound must also follow Hückel's rule, meaning it has 4n+2 π-electrons (where n is a whole number, like 0, 1, 2, etc.). Carbonyl group - C double bonded to O Carboxylic acid - contains carboxyl group. Add oic acid to ending Carboxyl group - C doubled bonded to O and single bonded to OH Combustion reaction - hemical reaction where a substance (usually a hydrocarbon) reacts with oxygen (O2) to produce energy in the form of heat and light. The products of complete combustion are typically carbon dioxide (CO2) and water (H2O). Condensation reaction - A condensation reaction is a chemical reaction in which two molecules combine to form a larger molecule, and a small molecule, often water or another simple compound (like HCl), is released as a byproduct. Cyclic hydrocarbon - A cyclic hydrocarbon is an organic compound that contains carbon atoms arranged in a closed ring structure. These hydrocarbons can have single bonds, double bonds, or a combination of both within the ring. Elimination reaction - An elimination reaction is a type of chemical reaction where two atoms or groups are removed from a molecule, resulting in the formation of a double or triple bond. This reaction often occurs in the presence of a base or heat and is the reverse of an addition reaction. Ester - Contains ester linkage. Alcohol + acid seperated by an O. Alkyl ending for alcohol and ote ending for the acid Esterification - chemical reaction in which a carboxylic acid reacts with an alcohol to form an ester and water. Ether - organic compound that contains an oxygen atom bonded to two alkyl or aryl groups Functional group - specific group of atoms within a molecule that is responsible for the molecule's characteristic chemical reactions Hydration reaction - a chemical reaction where a water molecule (H2​O) is added to a compound. This often results in the formation of a new product, typically by breaking a double or triple bond in an unsaturated molecule and attaching the H and OH groups from water to the molecule. Hydrocarbon - organic compound made up entirely of carbon (C) and hydrogen (H) atoms. Hydrolysis - a chemical reaction in which water (H2O) is used to break a bond in a molecule, resulting in the formation of two or more smaller molecules. Hydroxyl group - OH Isomer - a compound that has the same molecular formula as another compound but a different structure or arrangement of atoms. Structural isomers differ in the connectivity of atoms. Stereoisomers differ in the spatial arrangement of atoms. Ketone - compounds that contain a carbonyl group (C=O) bonded to at least one hydrogen atom. Carbonyl group is on interial carbon Organic halide - Same thing as alkyl halide. Above ^^ Oxidation reaction - chemical reaction in which a substance loses electrons, typically resulting in an increase in its oxidation state. Oxidation often involves the addition of oxygen to a compound or the removal of hydrogen from it. Primary alcohol - hydroxyl attached to carbon only attached to 1 other carbon Secondary alcohol - hydroxyl attached to carbon attached to 2 other carbons Substitution reaction - a type of chemical reaction in which one atom or group of atoms in a molecule is replaced by another atom or group of atoms Tertiary alcohol - hydroxyl attached to carbon attached to 3 other carbons Addition polymerization - a type of polymerization reaction in which monomers (small molecules) with a double bond (typically alkenes) undergo a reaction to form a polymer. In this process, the double bond in the monomer is broken, and the monomers link together to form long chains without the loss of any atoms. Condensation polymerization - a type of polymerization reaction in which monomers join together to form a polymer, with the elimination of a small molecule, usually water or methanol. This type of polymerization typically involves two different monomers, each having two or more functional groups (such as alcohol, amine, or carboxylic acid). Practice Questions: *on whiteboard* Unit 3 - Energy Changes and Rate of Reaction Key Terms: Calorimetry - an experimental technique used to measure energy changes in chemical systems. *different substances vary in their ability to absorb amounts of heat Chemical change - a process in which one or more substances are transformed into one or more new substances with different properties. typically accompanied by changes in energy, such as the release or absorption of heat Chemical system - a specific portion of matter in a given space that is being studied for changes in its chemical reactions or properties Endothermic - absorb thermal energy, heat (Q) flows from the surroundings into the system, usually causing a decrease in the temperature of the surroundings Enthalpy - total energy of a system Exothermic - release thermal energy, heat (Q) flows from the system to the surroundings, usually causing an increase in the temperature of the surroundings Heat - transfer of thermal energy between systems or bodies due to a temperature difference. Hess’s Law - The value of the enthalpy of a reaction is the same whether the reaction occurs as one step or as a sequence of several step Molar enthalpy - enthalpy change associated with a physical, chemical or nuclear change involving one mole of a substance Molar enthalpy of reaction - the change in enthalpy when one mole of a substance reacts under specific conditions, typically at constant temperature and pressure. Open system - can exchange both energy and matter with its surrounding Physical change - a transformation that alters the appearance or physical properties of a substance without changing its chemical composition Potential energy diagram - Vertical axis is the potential energy, the horizontal axis is called the reaction coordinate or reaction in progress As the bonds break and reform atoms are re-positioned, and changes occur in the potential energy of the substances When the reactants line is higher than the products line, this reveals a drop in potential energy, therefore is an exothermic reaction When the products line is higher than reactants line, this reveals an increase in potential energy, therefore is an endothermic reaction Specific heat capacity - the amount of energy required to raise the temperature of 1 g of a substance by 1°C or one K Standard enthalpy of formation - the enthalpy changes for compounds when they are formed from elements in their standard state 1) write one mole of the product in the correct state 2) write the reactant elements in their standard states Eg. Mg(s), O2(g) 3) choose equation coefficients for reactants to give balanced equations yielding one mole of the product Surroundings - everything outside the defined system in a scientific or thermodynamic context. They represent the entire environment that is not part of the specific system being studied. Temperature - (T) the average kinetic energy of the particles in a sample, measured in °C or K Thermal energy - sum of all the energy available from a substance as a result of the motion of its particles (kinetic energy of all the particles Activated complex - chemical species that has some partially broken and formed bonds, this point represents the max Activation energy - the minimum amount of energy required for atoms or molecules to undergo a chemical transformation or reaction. Average rate of reaction - specifically measures the overall change in concentration over a specific time interval. It represents the general speed of the reaction between two defined time points. determining the slope of the secant over a specific time period Catalyst - increases the rate of reaction by providing an alternative pathway, with lower activation energy Collision theory - a fundamental principle in chemistry that explains how chemical reactions occur and why they proceed at different rates. Chemical reactions occur only when reactant particles collide Instantaneous rate of reaction - determine the instantaneous rate of reaction by finding the slope of the tangent at any given point on the lin Rate-determining step - In the series of steps, the one that is the slowest is the one that controls the rate of the reaction Rate of reaction - the speed at which a chemical change occurs, expressed as a change in concentration per unit of tim Reaction intermediates - transient molecular entity formed during a chemical reaction that exists between the reactants and final products, Temporary chemical species produced in one step of a reaction, Extremely short-lived, Typically unstable and highly reactive Practice Questions: *on whiteboard* Unit 4 - Chemical Systems and Equillibrium Key Concepts Chemical reaction equilibrium - a dynamic equilibrium between reactants and products of a chemical reaction in a closed system Closed system - can exchange energy, but not matter, with its surroundings, In a closed system like this one chemical changes are continuing to take place however an appreciable change is not witnessed because the properties of the system remain constant Common ion effect - a chemical phenomenon where the solubility of an ionic precipitate decreases when a soluble compound containing an ion common to the precipitate is added to the solution. Dynamic equilibrium - a state in a reversible reaction where the forward and reverse reactions occur simultaneously at equal rates, resulting in no observable macroscopic changes. Equilibrium constant (K) - represents the relationship between reactants and products when a chemical reaction reaches dynamic equilibrium. Equilibrium law expression - Equilibrium Law describes a relationship between the ratio of the products and the reactants in a system at equilibrium For the general chemical reaction aA + bB < > cC + dD K = [C]C [D]d / [A]a [B]b Equilibrium shift - if [reactants] is increased, then equilibrium shifts to the right to make more product, if [product] is increased, then equilibrium shifts left to make more reactants Forward reaction - the direction of a chemical reaction that proceeds from reactants to products in a reversible chemical system,represents the reaction moving from left to right in a chemical equation LeChâtelier’s principl - a fundamental concept in chemical equilibrium that describes how a system responds to disturbances to maintain balance. Le Chatelier’s Principle and Temperature Changes: A + B -> AB + heat – exothermic reaction if heat is treated as a product, then lower temp – reduces [heat] so equilibrium shifts right to make more heat (and make more product) C + D + heat -> CD - endothermic reaction if temp is raised, increases [heat] and so equilibrium shifts right to use up more heat (and make more product) Le Chatelier’s Principle and Gas Volume – Pressure Changes For gases: if volume decreased – pressure increased equilibrium shifts to decrease pressure – in the direction of the side with the least # moles gas ex: N2 (g) + 3 H2(g)2 NH3 (g) increase pressure causes equilibrium, to shift right – 2 moles gas reduce pressure compared to 4 moles gas on the left Practice Questions: *on whiteboard* Unit 5 - Electrochemistry Key Concepts: Anode - is the electrode that the oxidation process occurs at Cathode - the electrode that the reduction process occurs at Electric current - The flow of electrons Electric potential difference (voltage) - the work required to move a unit charge between two points in an electric field. Electrode - piece of metal Electrolyte - substances that conduct electricity when dissolved in water Galvanic cell - uses redox reactions to transform chemical energy into usable electrical energy Half-cell - fundamental component of an electrochemical cell that consists of a metal electrode immersed in an electrolyte solution containing ions of the same metal. Oxidation - Loss of an electron Oxidation number - a positive or negative number corresponding to the apparent charge of the atom. Oxidation is an increase in oxidation number, reduction is a decrease in oxidation numbe Oxidizing agent - Any substance that promotes the oxidation of a substance, causes oxidation to occur (is reduced) Redox spontaneity rule - Recall that a Redox reaction occurs when one entity exchange electrons from another. If this type of reaction is able to occur between two entities the reaction is considered to occur spontaneously. Not all redox reactions happen spontaneous, Specific entities will have a greater ability to gain electrons than other substances (recall- if a substance gains electrons it can be considered an oxidizing agent Reducing agent - Any substance that promotes the reduction of a substance, causes reduction to occur (is oxidized) Reduction - Gain of an electron Standard cell - a galvanic cell where half cells contain half reaction entities @ SATP and 1.0 mol/L for aqueous entitie Standard cell potential - the max electric potential difference (voltage) of a cell operating under standard condition