Presentation on theme: "Part 1 History and Scientists Chemistry"— Presentation transcript:
1Part 1 History and Scientists Chemistry Atomic TheoryPart 1History and ScientistsChemistry
2Learning ObjectivesTLW research and describe the historical development of atomic theory (TEKS 6)TLW be introduced to the scientists behind the atomic theory (TEKS 3.F. & 6.A.)TLW begin to describe the relationship among electrons, protons, neutrons, atomic number, mass number, and isotopes (TEKS 6A, 6B, 11A)
3Anticipatory Activity What’s in the Box? Lab – to be done prior to beginning lecture from this PowerPoint
4Agenda I. Atoms – Building Blocks of Matter & Subatomic Particles II. Mass of AtomsIII. Meet the Scientists and Learn About Their DiscoveriesIV. Modern Day Atomic Theory
5I. Atoms A. Building blocks of Matter 1. Everything is made up of atoms2. Atom is Greek for indivisible3. There are three major parts to the atom called subatomic particles
6ATOM NUCLEUS ELECTRONS PROTONS NEUTRONS B. Subatomic ParticlesIons – lose/gain electronsCation – positiveAnion -- negativeATOMNUCLEUSELECTRONSequal in a neutral atomPROTONSNEUTRONSNEGATIVE CHARGEQUARKSAtomic Numberequals the # of...POSITIVE CHARGEIsotope – same number of protons, different number of neutronsNEUTRAL CHARGEMost of the atom’s mass.
7II. The Mass of Atom A. Protons 1. are positively charge 2. have a mass of 1.67 X kg3. Found in the nucleusB. Neutrons1. NeutralC. Electrons1. are negatively charged2. Have a mass of 9.11 X kg3. Found orbiting outside the nucleus
8To Put Nucleus Size in Perspective If an atom were the size of this stadium, then its nucleus would be about the size of a marble
9Something “Quarky” About Atoms Quarks are fundamental matter particles that make up protons and neutrons6 types – up, down, charm, strange, top, bottomOnly 2 (up and down) exist in protons and neutrons, others are unstable and randomly occurWe have yet to determine their massQuarks and electrons are considered to be the smallest units of matter in the universeDiscovered by Murray Gell-Mann in the late 1960’s
12Democritus (Greek philosopher) 1. Date = 400 B.C2. Discovery = Theorized the smallest unit of an element3. Importance = gave the term and definition of atom
134. Atom is Greek for “unable to divide” 5. Believed movement of atoms caused changes in matter he observed, but couldn’t prove it with evidence people would accept
14Molecules made of atoms John DaltonAtomic TheoryMolecules made of atomsBritish
15a. Every element is made of atoms John Dalton1. Date = 18032. Discovery =a. Every element is made of atomsb. atoms of same element exactly the samec. Atoms of different elements join together to form moleculesEnglish
16Importance = proposed the ATOMIC THEORY Atomic Theory (in beginning) =1. everything is made up of atoms2. atoms make up molecules3. atoms of the same element are the same4. Atoms cannot be divided5. in chemical reactions, atoms are combined,separated, rearranged..…. BUT NEVER destroyed6. aka Law of Conservation of Mass
17a. Order of elements is based on the Dimitri Mendeleev1. Date = ca. 18702. Discovery =a. Order of elements is based on theperiodic lawb. Periodic Law states properties of elements will occur in a regular pattern3. Importance =First periodic table of elements…….arranged by massRussian
19Eugen Goldstein 1. Date = 1886 2. Discovery = a. discovered protons using cathoderay tube. Rays were observed travelingin the direction opposite of thecathode rays.b. protons are positive3. Importance =atoms have both negative and positive particlesSwiss German
204. How?a. Using a cathode rayb. relationship between electricity and matterc. electric current was passed throughvarious gases at low pressure in a glasstube = cathoded. In Goldstein’s Experiment: Rays wereobserved traveling in the directionopposite of the cathode rays.e. Later we’ll learn that In Thomson’s Experiment:Cathode Rays were attracted to positiveelectrical charges.
21Discovery of the Protron In 1886, Eugen Goldstein used a cathode ray tube to discover the presence of a positively charged particle called a proton.Cathode ray tubes pass electricity through a gas that is contained at a very low pressure.
22a. discovered metals contain negatively charged particles William Crookes1. Date = 18872. Discovery =a. discovered metals containnegatively charged particles3. Importance =early indication of the electronBritish
23Electrons are negative J.J. Thomson“Plum Pudding” modelElectrons are negativeBritish
24J.J. Thomson1. Date = 18982. Discovery =a. discovered electronsb. electrons are negative3. Importance =atoms have both negative and positive particles
25Discovery of the Electron In 1897, J.J. Thomson used a cathode ray tube to discover the presence of a negatively charged particle called an electron.Cathode ray tubes pass electricity through a gas that is contained at a very low pressure.
26a. hot objects don’t emit energy continuously, like in a wave Max Planck1. Date = 18992. Discovery =a. hot objects don’t emit energycontinuously, like in a waveb. instead, energy is emitted in small, specific amounts called quanta3. Importance =original idea of quantum theoryGerman
27Electrons outside nucleus Ernest RutherfordDiscovered nucleusElectrons outside nucleusGold Foil ExperimentNew Zealand born Brit
28Ernest Rutherford1. Date = 19112. Discovery =a. discovered nucleusb. did a “gold foil” experimentc. atoms mostly made of space3. Importance =a. nucleus is very tiny, and positively chargedb. electrons outside of nucleus
29Rutherford’s Gold Foil Experiment Alpha particles are helium nucleiParticles were fired at a thin sheet of gold foilParticle hits on the detecting screen (film) are recorded
30Try it Yourself!In the following pictures, there is a target hidden by a cloud. To figure out the shape of the target, we shot some beams into the cloud and recorded where the beams came out. Can you figure out the shape of the target?
32Rutherford’s Experiment As a follow up to our Introductory Activity of What’s in the Box?…We will now conduct a simple experiment to determine the size and shape of an object by indirect means…. as did Rutherford when he developed Atomic TheorySee pages 45 & 46 in Chemistry Lab Manual (Prentiss Hall)See IPC Manual pages 122 & 123
33a. Radioactivity of isotopes 3. Importance = Marie Skodowska Curie1. Date = 19112. Discovery =a. Radioactivity of isotopes3. Importance =paved way for use of radioactive isotopes in medical field andother applicationsPolish-French
34technology to measure the number of protons in an atom Henry Moseley1. Date = 19132. Discovery = used x-raytechnology to measure thenumber of protons in an atom3. Importance = led to betterarrangement of Periodic Table by atomic number(more on the PT later….)English
35a. measured the quantity of charge on the electron Robert Millakan1. Date = 19162. Discovery =a. measured the quantity of chargeon the electronb. determined ratio of charge tomass of an electron3. Importance = determined massof an electronAmerican
37Niels BohrElectrons in energy levels (orbits)Danish
38Niels Bohr1. Date = 19132. Discovery =a. Electrons are in energy levelsb. s, p, d, f orbitalsc. 1st = 2 electrons;2nd = 8 electrons;3rd = 18 electrons4th = 32 electrons
39Energy Levels (more)Fixed energy levels are analogous to rungs on a ladderA person cannot stand between them, they climb from one to another to reach a greater heightSimilarly, an electron cannot exist between energy levelsTo jump from one energy level to another the electron must gain or lose energy
40Quantums of Energy Have you heard of the term “quantum leap”? A quantum of energy is the amount of energy required to move an electron from its present energy level to the next higher one.The higher the electron is on energy ladder, the farther it is from nucleus
41This is the Bohr Model 3. Importance = electrons orbit around nucleus in a certain pathway like planets around the sun.This is the Bohr Model
42Bohr’s Model and What It Led To Discovery Streaming VIDEO
432. Discovery = only one electron can occupy a given quantum state Wolfgang Pauli1. Date = 19252. Discovery = only one electron canoccupy a given quantum state3. Importance = determined howelectrons pair up and the direction oftheir movementAustrian-Swiss
44Erwin Schrödinger Atoms have no charge Same number of protons and electronsQuantum Mechanical Model
45Erwin Schrödinger1. Date = 19262. Discovery = electrons are impossible to find (like movingfan blades)3. Importance =a. Developed Quantum MechanicalModelb. Atoms are neutralc. Atoms must have the same number of protons and electrons
46Quantum Mechanical Model Mathematically basedDoes not define an exact path for electrons as did Bohr’s Model (orbitals)Estimates the probability of finding an electron in a certain positionSheldon from The Big Bang Theory sitcom explains Schrodinger’s Cat Model (YouTube)Another YouTube video of Schrodinger’s Cat
47determine position and momentum of a particle Werner Heisenberg1. Date = 19272. Discovery =can’t simultaneouslydetermine position andmomentum of a particle3. Importance = predicted better knownthe position, less known of momentumYouTube video on Heisenberg’s Uncertainty PrincipleAnother YouTube video on H’s Uncertainty PrincipleGerman
48James Chadwick1. Date = 19322. Discovery = demonstrated existence of neutron3. Importance = this accounted for the additional mass in the nucleus of an atom
49IV. Modern Day Atomic Theory 1. All matter is composed of atoms2. Atoms of different elements have different properties and masses3. Atoms can combine in chemical reactions (law of conservation of mass)4. Atoms can be divided5. Elements of the same atom can have different massesCalled isotopes – more later
50Projects Atomic Timeline - For more on other contributors and exciting moments in atomic theory history click on this linkFactBook Page for Scientist - link
51IV. Section Questions 1. Which “scientist” gave us the word atom? 2. Which scientist developed the atomic theory?3. Every element is made of atoms, atoms of the same element are exactly the same, different atoms make up molecules. These statements make up the what?
524. Which scientist discovered the electrons? 5. Which scientist discovered the nucleus?6. Which scientist discovered that electrons were in energy levels?7. Which scientist said atoms were neutral because they had equal number of protons and electrons?
538. What is the mass of protons? 9. What is the mass of neutrons?10. What is the mass of electrons?11. Which part of the atom has the least amount of mass?
54Review Key Points Atoms are building blocks for all matter Name the subatomic particlesName key scientists and their work in atomic theoryList the 5 points of modern atomic theory
55Independent Practice Atomic Theory Timeline Project link or Atomic Theorists FACTBook page linkWord Search – write the word with its definition on the backCrossword Puzzle