Chem 121 1st EditionExam # 1 Study Guide Lectures: 2 - 8Lecture 2 (January 22) Introduction to Chemistry 121- Classification of matter:o What is matter? Matter is anything that has mass and occupies spaceo What are the two categories of matter? Pure substances and mixtures What is a pure substance? A pure substance is composed of one type of matter (examples: table sugar, pure water, gold)- A pure substance is either an element or compound.o What is an element? An element is composed of one type of atom and CANNOT be broken down chemically (examples: Gold, Bromine, Helium)o What is a compound? A compound is composed of two or more elements that are fixed and definite proportions and CAN be broken down chemically (examples: Water, Sugar, Carbon Dioxide) What is a mixture? A mixture is composed of two or more types of pure substances (examples: milk, tap water, air, wedding ring)- A mixture is either homogeneous or heterogeneous.o What is a homogenous mixture? A homogeneous mixture has a uniform composition and can be seen through. Thereare no visible boundaries. They are clear and transparent in liquid and gas. (examples: pure air, saline) o What is a heterogeneous mixture? A heterogeneous mixture has two or more visible boundaries between components and cannot be seen through. There are one ormore visible boundaries and are opaque and muddy in liquid and gas. (examples: oil and water, fog, aquarium)Lecture 3 (January 27)- What are atoms? Atoms are the smallest identifiable particles. They are extremely small and are the building blocks of matter including molecules and ionso How many types of atoms are there? There are 91 different natural atoms and 20different synthetic (man-made) atoms.o What types of imaging machines are used to see atoms? Scanning tunneling microscopy and atomic force microscopy- Can matter be cut infinitely?o Old atomic theory was theorized by Democritus and he found that atoms compose matter and are tiny invisible particleso Modern atomic theory was adopted by Dalton, was revised by Thompson, andwas developed by Rutherford- Experiments on Atomso Electron CRT- JJ (Joseph John) Thomson (1897)- Negatively charged- Identical electrons from different atom- Charge-to-mass ratio: e/m=-1.76 x 108 C/g Oil-drop experiment- Robert Millikan (1909)- Minimum charge: e= 1.602 x 10-19 C- Mass of e= 9.10 x 10-28 g- Nuclear Atomo What Ernest Rutherford (1911) test? He tested Thompson’s blueberry muffin modelo What kind of particles did he use? α-particleso What were the results?  Most particles passed through Some particles deflected 1 in 20,000 bounced backo What was the conclusion of the experiment? Plum padding model was incorrect Atoms must mainly be empty space Tiny, extremely positively charged something inside of each atom- Modern Atomic Theoryo What is the modern atomic theory? The atom is an electrically neutral, spherical entity Has a positively charged nucleus and is surrounded by one or more negatively charged electrons Nucleus consists of protons and neutrons- What are elements defined by? They are defined by the number of Protonso What does the Atomic Number identify? It gives the identity of the elements Atomic number (Z)= # of protons What type of relationships do atomic numbers have? They have a one-to-one relationship In a neutral atom, what do the number of e- equal to? Number of e-= Z= number of p+- What is an isotope? An isotope is an atom of an element with the same number of p+ but has different numbers of n0o What does X represent? X= atomic symbol of the elemento What does A represent? A= mass number A= Z+N (where N= number of neutrons n0)o How are isotopes on Earth? They have unique relative abundance What are the natural abundances of carbon?-12C: 98.89%-13C: 1.11%-14C: trace- Atomic Mass Unit (amu)o 1 amu is equal to how many grams? 1 amu= 1.66054 x 10-24 go What is the exact mass of a 12C atom? 12 amu exactlyo How many Dalton (D) are equal to amu? 1 amu= 1 Dalton- Atomic Mass (Atomic Weight)o What is the formula for Atomic Mass? Atomic Mass= (mass of isotope 1 x % abundance 1) + (mass of isotope 2 x % abundance 2) + …o What is the formula for Atom Mass of Carbon? Atomic Mass of C= (massc-12 x abundance) + (massc-13 x abundance)- Molecules and Ionso What is an ion? An ion is a charged atom or a cluster of atomso What are Cations? Cations are positively charged ions by losing electronso What are Anions? Anions are negatively charged ions by gaining electronso True or False: An ion has the same atomic mass as the parental atom.  TrueLecture 4 (January 29)- Measuremento What is precision? Precision is how close the measurements are to each othero What is accuracy? How close the measurements are to the real/ true valueo What is uncertainty? Uncertainty is when one estimates when taking a reading ina measurement o Tip to remember: more digits= better certainty= better precision- Units of Measuremento What is a Unit? A unit is a standard quantity used in measurements; can be added, subtracted, multiplied, or divided (essential for any experimental science)o What are the common SI base units? Dimension Unit Name Unit AbbreviationMass Kilogram kgLength Meter mTime Second sTemperature Kelvin KAmount of Substance Mole (6.022x1023) molo What is the derived unit of Force? Newton (N: (kg x m)/s2)o What is the derived unit of Volume? Cubic Meter (m3) Other common units: L, mL, cm3 **MEMORIZE: 1 mL = 1 cm3o What is the derived unit of Pressure? Pascal (Pa: kg/ m x s2)) Other common units: atm, torr, kPao What is the derived unit of Energy? Joule (J: (kg x m2) / s2) Other common units: cal, Cal, kJo What is the derived unit of Electrical Charge? coulomb (C) Other common units: mCo English Units: 1 inch = 2.54 cm  MEMORIZEo What is the purpose of Prefix Multipliers? The purpose is to express very large or small quantities in a compact way.o For Prefix Multipliers, how do you change the values of the unit? By powers of 10 - Densityo What is Density? Density is the mass per unit volumeo What is the equation for density (d)? d= m/Vo What is the basic unit of density? Kg/ m3 Other common units: g/cm3, g/mLo What is the equation for mass (m)? m= d x Vo What is the equation for volume (V)? V= m/ do What is Intensive Property? Independent of the size or amount of the substanceo What is intensive property used for? It is used to identify pure substances (important)o What is Extensive Property?