Lecture 2 - Isotopic Notation, Substances

Wednesday, January 10, 2024

10:02 PM

"Isotopes are atoms which have the same nuclear charge but different ﷟HYPERLINK "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl"atomic weights." ﷟HYPERLINK "https://www.nobelprize.org/prizes/chemistry/1922/aston/biographical/"Francis William Aston (Biography) ﷟HYPERLINK "https://www.nobelprize.org/uploads/2018/06/aston-lecture.pdf"Francis W. Aston - Nobel Lecture 1922 - Great summary of what we will learn Welcome back to CHEM 101 Homework this week: Complete Syllabus Quiz and Reading Quiz 1. (past due) If I don't get the syllabus quiz you will get an email from me after class asking about your intent to take the course. No reply by 12:00 PM Friday and you will be dropped from both lecture and lab. I will accept the first reading quiz until Friday (only time I will accept one of these late) Reading Quiz 2 and Surveys (by end of day Friday) Aktiv Chemistry HW 1 (1.1-1.4) (by end of day Sunday) My office hours will start in the CIC next Friday from 11AM - 1PM. If you have questions you are free to go to the CIC to get help anytime they are open. Additionally, you can make in-person or Zoom appointments with me via the ﷟HYPERLINK "calendly.com/bricejurban/office-hours"link in the syllabus page on canvas. Email is also great! You can stop by office at any time this Friday if you only have a few questions or want to say hi, otherwise just make an appointment :) Today's schedule: First 45 minutes of Class More information on subatomic particles and early atomic models Plum-pudding and nuclear model of the atom Defining characteristic of elements Protons not Mass How many elements are there (so far?) Atomic symbols An appeal to memorize these ﷟HYPERLINK "https://quizlet.com/814496647/elemental-symbols-and-names-flash-cards/?funnelUUID=983fdaf0-ec1f-4aeb-b943-1404b11cef95"50 elements Elements with different numbers of neutrons: Isotopes Isotopic/Nuclide Notation Mass number Nuclide How were isotopes discovered?
How were isotopes discovered? Mass Spectrometry Percent Abundance and (relative) atomic mass/weight Examples of isotopes Isotopes of Hydrogen, Carbon, Oxygen, Uranium, etc. How many isotopes are there?? Spoiler: It's a lot 251 stable >3000 characterized most of which are unstable ﷟HYPERLINK "https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html"Live Chart of Nuclides Practice relating protons, neutrons and isotope notation Revising Dalton's Postulates What was Dalton's mistake with water Questions/5 min break Last 25 minutes of Class Classifying matter Why do chemists have so many terms? Pure substances (Elements and Compounds) diatomic elements Mixtures (homogeneous and heterogeneous) Practice with classifying matter Questions Early Experiments Investigating the Atom Experiment Importance Electron 1897 (Thomson) Passed electricity through an evacuated tube and noticed a glow emanating from the cathode metal plate (positive side of tube) toward the anode (negative side). This light could be deflected by magnetic and electric fields and had mass. There are particles much smaller than atoms that are negatively charged called electrons Led to the plum pudding model which has a diffuse positive charge and an undefined amount of electrons per atom Nucleus Alpha Particles (helium nuclei) deflected by very There is a heavy concentrated positive charge in the atom called the nucleus
Nucleus 1911 (Rutherford) Alpha Particles (helium nuclei) deflected by very thin sheet of gold foil There is a heavy concentrated positive charge in the atom called the nucleus Proton 1917 (Rutherford) Bombarded nitrogen with alpha particles and observed hydrogen nuclei being emitted The hydrogen nuclei or proton is the lightest, simplest component of all atoms with a positive charge equal in magnitude and opposite in charge to that of the electron Neutron 1932 (Chadwick) Bombarded beryllium with alpha particles and discovered a particle with a mass similar to a proton There are particles that add mass to atoms without changing their identity known as neutrons. These particles are also in the nucleus but have no charge. Untitled picture.png (a) The Thomson "plum-pudding" model: electrons are spread throughout a sea Of positive charge. Untitled picture.png (b) The Rutherford nuclear model: a central nucleus contains almost all the mass and all the positive charge; electrons are spread throughout empty space. Summary of Subatomic Particles Untitled picture.png SUBATOMIC PARTICLES TABLE 1.1 Particle Electron Proton Neutron Mass (kg) 9.109 x 100' 1.672 X 1.675 X Mass (amu) 5.486 x 1.0073 1.0087 Charge (e) Location Outside nucleus Inside nucleus Inside nucleus *e is the elementary charge and has the value 1.602 ×﷐10﷮−19﷯ Coulombs ** 1 amu = 1.6605 ×﷐10﷮−27﷯ kg Scientific Notation
Scientific Notation What is this notation × ﷐10﷮−31﷯ mean? It simply means divide by ten 31 times 0.000 000 000 000 000 000 000 000 000 000 9109 = 9.109 ×﷐10﷮−31﷯ kilograms The mass of a subatomic particle is very small, so we use scientific notation to avoid writing all the zeros. We can also use this notation to write very big numbers. We will soon learn that there is an incredulous amount of atoms in any macroscopic amount that we measure and that light travels so much faster than we can imagine. 602 214 179 000 000 000 000 000 = 6.02214179 × ﷐10﷮23﷯ atoms in 1 mole 299 792 458 ﷐𝑚﷮𝑠﷯ = 2.99792458 × ﷐10﷮8﷯ meters per second= speed of light To more easily compare subatomic particles atomic mass units (amu) are employed; a conversion factor based on the mass of the carbon-12 isotope (explain soon). Elements Multivitamin.JPG Amount Per Sewing Caldtrn % value 210 mg (a Camm Catbmate & Dcaäum Phosphate) 1m (a Fns Furrate) 8 mg 20 mg une (c Potassium Iodide) 150 mcg Magnæn(cMqrBitmOide) 100 mg Zrc(aZncOxjde) 11 mg Eium(aSodunSdenate) 100 mcg (a Sulfate) 0.9 mg Manganese SUfate) 2.3 mg Chromium (as Chromium Picolirnte) 35 mcg Molybdenum (as Sodium Mob,'bdate) 50 mcg Chloride@Potasin Chloride) 72 mg Potasium (as Potasium Chloride) 80 mg 2% 100% 100% 182% 100% 100% 100% 111% 3%
Multivitamin.JPG Amount Per Sewing Caldtrn % value 210 mg (a Camm Catbmate & Dcaäum Phosphate) 1m (a Fns Furrate) 8 mg 20 mg une (c Potassium Iodide) 150 mcg Magnæn(cMqrBitmOide) 100 mg Zrc(aZncOxjde) 11 mg Eium(aSodunSdenate) 100 mcg (a Sulfate) 0.9 mg Manganese SUfate) 2.3 mg Chromium (as Chromium Picolirnte) 35 mcg Molybdenum (as Sodium Mob,'bdate) 50 mcg Chloride@Potasin Chloride) 72 mg Potasium (as Potasium Chloride) 80 mg 2% 100% 100% 182% 100% 100% 100% 111% 3% The elements are necessity for life as we know it. There are 94 naturally occurring elements on Earth. (Hydrogen through Plutonium) 80 of these from Hydrogen (element 1) to Lead (element 82) have at least one stable isotope that does not undergo radioactive decay. (Technetium (element 43) and Promethium (element 61) are notable exceptions) The transuranium elements are synthetic and have been artificially produced through nuclear reactions. (elements with greater than 92 protons). As of now, scientists have discovered 118 elements, the last of which is element Oganesson (Og) and named after living scientist Yuri Oganessian, a Russian nuclear physicist who significantly contributed to the discovery of superheavy elements. The most recent element to be discovered was element 117 Tennessine in April 2010 (during your lifetime!) by a collaboration of Russian scientists at the Joint Institute for Nuclear Research in Dubna, Russia, and American scientists at the Oak Ridge National Laboratory in Tennessee, USA. Some elements have been known since antiquity, but the discovery of most was not an easy feat. Most elements are present in very trace amounts, and almost none are present in pure form and therefore must be isolated. The hunt for new elements has not abated. I predict that element 119 or 120 will be discovered in our lifetime and then we will have to add another row to our periodic table. That will be truly an amazing day. Is there a fundamental limit? Some physicists believe that there is an island of stability in the region of superheavy elements that would have longer half-lives. Additionally some quantum theorists believe that in the theoretical element 137, the electromagnetic radiation would compete with the nuclear force so strongly that speeds faster than the speed of light would be necessary (impossible), so the atom would be inherently unstable. Applying atomic theory we can understand the differences in the elements through their subatomic particles. The chemical properties of an element depend solely on its atomic number (Z), which is the charge on its nucleus expressed in terms of the unit charge, e.
The chemical properties of an element depend solely on its atomic number (Z), which is the charge on its nucleus expressed in terms of the unit charge, e. Therefore the elements are arranged 1 through 118 on the periodic table simply by the numbers of protons that they contain in their nucleus. Atomic symbols An appeal to memorize these ﷟HYPERLINK "https://quizlet.com/814496647/elemental-symbols-and-names-flash-cards/?funnelUUID=983fdaf0-ec1f-4aeb-b943-1404b11cef95"50 elements ﷟HYPERLINK "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl"Isotopes Previously scientists arranged the elements by their atomic weight (also called atomic mass). But some elements with less protons are actually heavier. Chadwick's discovery of the neutron helped scientists understand Francis Aston's isotopes, i.e. why a given element can have a different atomic mass with the same number of protons X = Symbol Z = Atomic Number = Number of Protons A = Mass Number = Number of Protons + Neutrons Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Daltons Postulates Revisited All matter is made of atoms that are indivisible All atoms of a given element are identical in mass and properties Compounds are formed by a combination of two or more different kinds of atoms A chemical reaction is a rearrangement of atoms We now know that Dalton's first and second postulates are false. Atoms are made of subatomic particles #1 Elements can have different masses = Isotopes #2 Name (First and Last) 1 thing you learned 1 thing you liked/didn't like about lecture 1 thing you still want to learn more about Classifying Matter - Next week Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings

 

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