Final Exam Study Notes CP Chemistry Period 5 Physical and Chemical Properties Physical Property- a trait or characteristic that you can observe without changing the identity of the substance Chemical Property - a trait you can observe by changing the identity of the substance Physical Properties Chemical Properties Size Flammability Color
Digestibility Texture Decomposable Smell Ability to oxidize Mass Reactivity inert (not reactive) Taste Density Volume Area Melting Point Malleability Elasticity Solubility
Physical and Chemical Changes Physical Change- a change that affects only physical properties and does not alter the identity of the substance Chemical Change- a change that alters the identity of our substance Physical Changes Examples in terms of a piece of paper Crumpled paper Ripped paper Drawn on paper Stomping on paper Chemical Changes Examples in terms of a piece of paper Eating it
Digesting it Burning it Elements, Compounds, and Mixtures Element- a substance that cannot be separated by chemical or physical means Compound- a substance made up of two or more elements only separated by chemical means Atom- smallest unit of an element Molecule- smallest unit of a compound Elements, Compounds and Mixtures cont. Mixture- a combination of substances thhat are not chemically combined. These can be separated physically
Homogeneous: looks same throughout Heterogeneous: composed of different parts Homogeneous Heterogeneous Accuracy and Precision True Data is accurate. Repeatable data is precise. Accurate & Precise 3 2.5 2 1.5
1 0.5 0 Mass 1 Mass 2 Counting Protons/Neutrons/Electrons
The mass number of the element eqauls the number of protons in an element The number of protons is also the number of electrons unless its an ion To find the neutrons you subtract the atomic number from the mass number Isotopes Are atoms that have lost or gained neutrons, same element but different number of neutrons Radiation particles/ Nuclear
equations Alpha- 4 2 H- stopped by clothing or skin Beta- -1
e- stopped by a sheet of lead Gamma- stopped by several inches of lead, most dangerous Nuclear reactions happened when there is an unstable particle and eventually gives off a particle of radiation 0
Ions Atoms that have lost or gained electrons atoms turn into ions when electrons move Ions have a charge There are negative electrons and positive electrons How Ions are formed:
Positive ions have lost electrons Negative ions have gained electrons Positive ions are called cations Negative ions are called anions When atoms are most stable they have an octet Octet- 8 electrons in the outer most energy level Covalent Bonds Share electrons between two atoms Properties
Low melting point Molecule structure Gases, liquids, soft solids Poor conductors of heat Poor conductors of electricity Typically 2 non-metal atoms Ionic Bonds They trade electrons between the two atoms
Ions must form from the atom Properties High melting point Crystal lattice structure Hard solids Brittle Good conductors of heat Good conductors of electricity Typically 1 metal and 1 non metal Wavelength
Waves of Light: electromagnetic radiation (light) moves as a wave Crest Wave Trough Wavelength/Frequency = Wavelength: Distance from crest to crest on a wave v= Frequency: How often a wave passes by in a second (s-1) Wavelength and Frequency are inversely related Wavelength increases, Frequency decreases
Wavelength decreases, Frequency increases Calculations E=h E= Energy (Joules) h= Planks Constant (6.626 x10-34) = Frequency Example: A yellow light has a wavelength of 600nm a) What is the frequency of the light? b) What is the Energy of the light? Answers on next slide Answer Frequency
a) = 600nmn v= x c= 3.0 x 108 m/s = c/v 600nm x 1n/10 x 9nm= 6.0 x 10-7m 6.0 x 10-7m= 3.0 x 108 m/s /v V= 3.0 x 108 m/s / 6.0 x 10-7m = 5.0 x 1014 s-1 Answer- Energy
E=hv E= ? h= 6.626 x10-34 J(s) v= 5.0 x 1014 s-1 E= (6.626 x10-34 ) 5.0 x 1014 3.31 x 10-19 J Ionization Energy The amount of energy needed to remove one electron from an atom Size of atom determines how easily electrons are removed- Increases up and to the right on the Periodic Table
Big atoms lose e- with Noble gases all have elect minimal effort negativities equal to zero Little atoms lose e- with a If an atom needs a lot of huge amount of energy energy to remove an electron its because it needed really wants the e- Periodic Trends Properties of elements can be predicted using the location on the periodic table
Electron Configuration Family and Periods Densities Reactivity Atomic radius Ionization Energy Electronegativity Atomic Radius The distance from the nucleus to the outermost elections (in the highest energy orbital filled) As electrons fill into higher energy orbitals, the Rb 5s1 radius of the atoms gets bigger!
K 4s1 Na 3s1 Rb Na K Atomic Radius Within an energy level adding more protons makes the radius of atoms smaller because the protons can hold the electrons in closer P 3P3
P S 3 P4 S Cl 3P5 Cl Question Put in order smallest to largest:
Rb, P, Na Answer on next slide Answer Na, Rb, P Periodic Table Families and Periods Groups (families) = The columns on the Periodic Table Periods = Rows on the Periodic Table Elements arranged by atomic number Column 1: #1 Silvery White Column 2: React with water to form a base
Column 3: 5,8,9,10,11,12 All metals Form colorful solutions Hard Brittle Metallic Versatile in bonding ability Charges: +2, +3
Periodic Table Families and Periods Column 14 Charge +4 -4 Non-metallic Can bond with positive or negative ions Solid at room temperature Relatively low reactivity Column 16: Oxygen Family
Charge: -2 Non-metallic Bonds with itself Shares electrons with other elements Column 17: Halogens - - Non-metallic
Charge -1 Very reactive with positive ions Not solid at room temperature Colored Gas Column 18: Noble Gases Non-Metallic Non Reactive Charge: 0 VSEPR Molecule Geometries VSEPR is a model of molecular structures based on the idea that
ideal structures minimize electron pair repulsions Used to draw and evaluate Lewis Structures Bare electrons are the most repulsive! Molecular Geometry Models Looking at the molecular geometry of a single atom, not of an entire molecule 3D Figures to represent Lewis
Structures Constituent groups are the things bonded to the atom under scrutiny Dashed lines represent a bond behind the plane of the paper; wedged lines represent a bond Planar Geometry Linear 1-2 Constituents 0 Lone Pairs Bond Angle: 180
Trigonal Planar 3 Constituents 0 Lone Pair Bond Angle: 120 Bent
0 Lone Pair Bond Angle: 109.5 Trigonal Pyramidal 3 Constituents 1 Lone Pair Bond Angle: 107.3
Bent 2 Constituents 2 Lone Pairs Bond Angle: 104.5 Lewis Dot Diagrams Lewis dot structure is a drawing of how the atoms are bonded together covalently using valence electrons. You need to know Shared pair= 2 electrons shared by 2
atoms (bond) Lone pair= 2 electrons not shared by atoms (unshared pair) How to draw Lewis Dot Structure 1. Count the total valence electrons for the molecule Ex: SCl2=20 valence electrons 2. Select a central atom. look for= *the only one of its kind. *less electronegative Ex: SCl2= S is central atom because
its alone How to draw Lewis Dot Structure 3. Set up the elements as symmetrical as possible. Ex: SCl2= Cl S Cl 4. Draw in shared pairs by drawing a line. Ex: SCl2= Cl-S-Cl How to draw Lewis Dot Structure
5. Account for electrons used from total you started with.(Shared pairs=2 electrons) Ex: 20 valence electrons -4 shared electrons ___ 16 unshared electrons How to draw Lewis Dot Structure 6. Fill in unshared pairs around the outside of elements Ex: How to draw Lewis Dot
Structure 7. When there isnt enough electrons for every element to have an octet, we share more pairs. Ex: How to find polarity in molecules When finding the polarity in molecules you need to find out if the bonds are polar or non-polar first. Polar bond- when 2 atoms share
electrons unequally Non-Polar bond- share electrons completly even. How to find polarity in molecules Polar Molecules- Molecules where one side of the molecule has more electrons than the other. 1. if there is a lone pair on the center atom, it is polar 2. If bonds are unequal polarity, than the
molecule is polar How to find polarity in molecules Non-Polar Molecules If there is no lone pairs on the center atom If the bonds are equal polarity 5 Types of Chemical Reactions Synthesis:
5 type of chemical reaction) Synthesis all you have to do is combine the two reactants to get your products Decomposition you break up your reactants and get two products Single replacement take either the positive or negative ion (by itself) and replace it with the positive or negative ion from a formula in the equation Double replacement you take the positive ion from one formula and put the negative ion from the other formula to create a new formula, do this again with the left over positive and negative ions. (positive come first) Combustion always ends up with carbon dioxide and water
Law of Conservation of Matter Matter can neither be created nor destroyed In chemical equation its crucial to make sure its balanced because, if its not balances it goes against the law of conservation of matter because it creates (or destroys) matter Balancing Equations According to the law of conservation of matter you have to balance all of your equations so that you dont create or destroy matter. NaOH + Cl2 NaCl + OH This is not balance because you have two chlorines in the reactants and only one on the product side
So, all you have to do is add a coefficient in order to balance it: 2NaOH + Cl2 2NaCl + 2OH Net Ionic Equations Aqueous substance dissociate A complete ionic equation shows all the ions and molecules in a reaction Zn (s) + CuSO4 (aq) ZnSO4 (aq) Complete ionic equation: Zn (s) + Cu+2 (aq) + SO4-2 (aq) Zn+2 (aq) + SO4-2 (aq) +Cu (s) NET IONIC: Anything thats AQUEOUS thats the same on both sides
you can cancel out So you can get rid of SO4-2 (reactant side) AND SO4-2 (product side) Final net ionic equation: Zn (s) + Cu (aq) Zn (aq) + Cu (s) Problems 1. What type of reaction is this? Mg + KCl MgCl + K 2. Balance the following equations: ___ Al + ___ O2 _____ Al2O3 ___CuS + ____ O2 ____CuO + _____ SO2 ____ Ca3P2 + ____ H2O ____ Ca(OH)2 + ___ PH3
3. Write the net ionic equation for: AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) ANSWERS 1. single replacement
2. 4 Al + 3 O2 2 Al2O3 3. 2 CuS + 3 O2 2 CuO + 2 SO2 4. (1) Ca3P2 + 6 H2O 3 Ca(OH)2 + 2 PH3 5. AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq) Complete ionic = Ag+1 (aq) + NO3-1 (aq) + Na+1(aq) + Cl-1(aq) Ag+1 (aq) + Cl-1 (s) + Na+1 (aq) + NO3-1 (aq) Net Ionic = Ag+1 (aq) +Cl-1 (aq) AgCl (s) The Factor Label Method A ratio used to convert the unit you have into the desired unit Example: If you are given one day, how do you convert it into the amount of seconds in a
day? Cross cancel Answer: the units!! 1 day* 24 hours*60 minutes*60 sec 1 day 1 hour 1 min The Factor Label Method Cont. The factor label method is useful in converting metric prefixes The Metric Prefixes are: TGMKHDBDCMMNP The Great Mister King Henry Died By Drinking Chocolate Milk Monday Night Partying
Tetra Giga Mega Kilo Hecto Deca BASE Deci Centi Mili Micro Nano Pico You can use Metric conversions to change from prefix to prefix! Converting Moles, Liters, Grams & Particles 1 Mole = 6.02 X 1023 things 6.02 X 1023 = Avogadros Number Moles to Particles/Liters/Grams: mole of element X 6.02*1023 = # with desired unit 1 Mole
Molar Mass To find the molar mass you must refer to the periodic table Look up each atomic mass of the element and add them all together to find the molar mass If there is a subscript then you must multiply the atomic mass by the subscript Empirical Formula Empirical formula= the lowest terms ratio of elements in a formula (Not the true formula) To calculate the empirical formula you must find 1. 2. 3.
4. Percent to Mass Mass to Mole Divide by small Multiply until whole Molecular Formula Molecular Formula= The true formulas for a compound (Not lowest terms) To find the molecular formula you must divide the actual molecule mass by the empirical formula mass Example: OH is the empirical formula, the actual formula has a mass of 34 g/mol, what is the molecular formula?
34 g/mol = 2 17 g/mol so OH becomes OH 2 2 Percent Composition To calculate the % composition you must use the following equation: Mass of particle * 100
Mass of whole States of Matter Gas Forms to shape of container Spread apart atoms Solid Atoms tightly compacted
Definite shape and volume Liquid Definite volume Moderate spacing of atoms Parts of Solutions Solute Dissolved by the solvent in the solution
Ex: Salt in salt water Solvent Substance that does the dissolving Ex: Water in salt water Phase Diagrams/ Heating Curves Phase Diagrams Shows what temperature and pressure combinations can create each state of matter for a particular chemical. Heating Curves
Shows the temperatures at which changes in states of matter occur and describe how a substance uses heat. Molarity Calculations Molarity= moles of substance/ volume(L) Ex: The chemical Carbon Dioxide has a volume of 2L. Find the concentration of Carbon Dioxide if it has a mass of 24.02g Grams to Moles using Molar Mass conversions.
24.02g*1mol/12.01g/mol= 2mol Then use the formula M(Molarity)=mol(Moles)/Volume(L) M=2mol/2L M=1M Intermolecular Forces Intermolecular Forces The forces of attraction between molecules. Vander Waal's(London Dispersion) Hydrogen Bonding Dipole-Dipole
SPECIFIC HEAT Specific Heat Capacity- The amount of heat needed to raise the temperature of one gram of substance one degree Celsius or one degree Kelvin. Molar Heat Capacity- The amount of heat needed to raise the temperature of one mole of substance one degree Celsius or one degree Kelvin. S P E C I F I C H E AT C A L C U L AT I O N S q = m C Heat (Joules)
T Change in Mass temperature (g) (kelvin or or celsius) moles Specific (mols) or molar Tf Ti heat capacity EXAMPLE PROBLEM
12g of water is heated from 15 degrees Celsius to 35 degrees Celsius. How much heat was absorbed by the water? (The specific heat capacity for water is 4.184 J/g degrees Celsius). Q = ? m = 12 g C = 4.184 J/g q = 12 * 4.184 * 20 q = 1004.16 J T = 20 degrees Celsius PROPERTIES OF ACIDS Sour
Burn/ sting React with metal Electrolyte (conducts electricity) pH less than 7 Releases hydrogen ions in water Accept an electron pair PROPERTIES OF BASES Bitter Slippery Non-reactive with metals Electrolyte Releases hydroxide ions in water Donate an electron pair
PH CALCULATIONS The pH scale is a numerical system that expresses the acidity of a solution What is the pH of a solution that has [H+] of 1.38 * 10-11 ? (plug into your calculator) Ans: pH = 10.86 P OH CALCULATIONS
A numerical scale that measures solutions by basicity. pOH = -log [OH-] What is the pOH of the solution you used in the last slide? (plug into your calculator) Ans: 3.14 Hint: pH + pOH = 14 H + CALCULATIONS [H+] = 10-pH Example: Determine the concentration of [H+] in the solution. pH = 3.0
Plug into your into your calculator by clicking 2nd and log Ans: 1 x 10-3 M [OH-] CALCULATIONS [OH-] = 10-pOH Example: Determine the [OH-] in the solution given the pOH is 4.0. Ans: 1 x 10-4 M Kinetic Molecular Theory
Definition: A theory concerning the thermodynamic behavior of matter, especially the relationships among pressure, volume, and temperature in gases. Absolute Zero and STP STP is used for measuring gas temperature and volume. STP means standard temperature pressure. Absolute zero is used for Absolute zero is
the point where no more heat can be removed from a system, according to the absolute or thermodynamic temperature scale. This corresponds to 0 K or 273.15C. Measuring pressure Pressure is measured using a barometer. The glass tube on the barometer contains a vacuum that allows mercury flow
up it when pressure is excreted on the surface of the mercury Pressure is usually
measured in: Atmospheres (atm) Bar (bar) Pascals (pa) Millimeter of Mercury (mmHg) Torr (torr) Pressure Conversions PRESSURE CONVERSION PROBLEM
1 1 1 1 1 atm= 101.325 Pa bar= 100.025 Pa Torr= 133.32 Pa MMHg= 133.32 Pa MMhg= 1 Torr
A radio station announcer reports the atmospheric pressure to be 99.6 kPa. What is the pressure in atmospheres? In millimeters of mercury? Pressure Problem answer 99.6 kPa x 1 atm/101.3 kPa = 0.983 atm 0.983 atm x 760 mm Hg/1 atm = 747 mm Hg
Answer 0.983 atm; 747 mm Hg Gas Laws Gas laws describes observed behaviors of gasses. Charles law equation: Gay-lussac law equation:
More Gas Laws Grahams Law: Ideal Law: Dalton Law: Gas Law Problems 1) In a thermonuclear device, the pressure of 0.050 liters of gas within the bomb casing reaches
4.0 x 106 atm. When the bomb casing is destroyed by the explosion, the gas is released into the atmosphere where it reaches a pressure of 1.00 atm. What is the volume of the gas after the explosion? 2) On hot days, you may have noticed that potato chip bags seem to inflate, even though they have not been opened. If I
have a 250 mL bag at a temperature of 19 0C, and I leave it in my car which has a temperature of 600 C, what will the new volume of the bag be? Gas Law Answers 1) 2.0 x 105 L 2) 285 mL
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