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 Color Texture Smell Mass Taste Density Volume Area Melting Point Malleability Elasticity Solubility • • • • • Flammability Digestibility Decomposable Ability to oxidize Reactivity inert (not reactive) 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 Chemical Changes Examples in terms of a piece of paper • Crumpled paper • Ripped paper • Drawn on paper • Stomping on paper 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 Mass 1 1 Mass 2 0.5 Trial 5 Trial 4 Trial 3 Trial 2 Trial 1 0 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 Are atoms that have lost or gained neutrons, same element but different number of neutrons Alpha- 42H- stopped by clothing or skin Beta- 0 -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 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 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 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 • λ= 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=h𝜐 • E= Energy (Joules) • h= Plank’s Constant (6.626 x10-34) • 𝜈= 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) 𝜆= 600nmn v= x c= 3.0 x 108 m/s 𝜆= 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 • Big atoms lose e- with minimal effort • Little atoms lose e- with a huge amount of energy needed - Increases up and to the right on the Periodic Table • Noble gases all have elect negativities equal to zero • If an atom needs a lot of energy to remove an electron its because it 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, Rb 5s1 the 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 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! 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 coming toward you • • • • Linear 1-2 Constituents 0 Lone Pairs Bond Angle: 180 • • • • Trigonal Planar 3 Constituents 0 Lone Pair Bond Angle: 120 • • • • Bent 2 Constituents 1 Lone Pair Bond Angle: <120 • • • • Tetrahedral 4 Constituents 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 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) 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 it’s alone 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 5. Account for electrons used from total you started with.(Shared pairs=2 electrons) Ex: 20 valence electrons -4 shared electrons ___ 16 unshared electrons 6. Fill in unshared pairs around the outside of elements Ex: 7. When there isn’t enough electrons for every element to have an octet, we share more pairs. Ex: When finding the polarity in molecules you need to find out if the bonds are polar or nonpolar first. Polar bond- when 2 atoms share electrons unequally Non-Polar bond- share electrons completly even. 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 Non-Polar Molecules If there is no lone pairs on the center atom If the bonds are equal polarity • Synthesis: • Ex: Cu+3 + O2 Cu2O3 • Decomposition • Ex: MgCl2 Mg+2 + Cl • Single Replacement • Ex: MgCl2 + Cu+2 Mg + CuCl2 • Double Replacement • Ex: 3MgCl2 + Cu2O3 3MgO + 2CuCl3 • Combustion • Hydrocarbon + oxygen CO2 +H2O • CH3OH + O2 CO2 + H2O • 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 • Matter can neither be created nor destroyed • In chemical equation it’s 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 • According to the law of conservation of matter you have to balance all of your equations so that you don’t 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 • 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 that’s AQUEOUS that’s 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) • 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) • 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? Answer: 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 = Avogadro’s 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 Mass of whole * 100 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. SPECIFIC HEAT CALCULATIONS q = m C Heat (Joules) Mass (g) or moles (mols) T Change in temperature (kelvin or celsius) Tf – Ti Specific or molar 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 T = 20 degrees Celsius q = 12 * 4.184 * 20 q = 1004.16 J 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 Definition: A theory concerning the thermodynamic behavior of matter, especially the relationships among pressure, volume, and temperature in gases. 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 -273.15°C. 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 CONVERSION PROBLEM 1 atm= 101.325 Pa 1 bar= 100.025 Pa 1 Torr= 133.32 Pa 1 MMHg= 133.32 Pa 1 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? 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 describes observed behaviors of gasses. 𝐵𝑜𝑦𝑙𝑒𝑠 𝑙𝑎𝑤 𝑒𝑞𝑢𝑎𝑡𝑖𝑜𝑛: 𝑃𝑉 = 𝑃2𝑉2 𝑉 𝑇 𝑉2 Charles law equation: = 𝑇2 𝑃 𝑃2 Gay-lussac law equation: = 𝑇 𝑇2 𝑃𝑉 𝑃2𝑉2 𝐶𝑜𝑚𝑏𝑖𝑛𝑒𝑑: = 𝑇 𝑇2 Grahams Law: Ideal Law: Dalton Law: 𝑀𝑀1 𝑀𝑀2 = 𝑉2 𝑉1 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? 1) 2.0 x 105 L 2) 285 mL