VWT 272 Week 3 Quiz 2 Number of quizzes taken 27 Min 4 Max 29 Mean 20.3 Median 22 Mode 27
Week 3 The Atom and the Periodic Table We must be clear that when it comes to atoms, language can be used only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images and establishing mental connections. Niels Bohr (1855-1962)
Plan of Study The Atom The Periodic Table
The Atom
The Atom & Dead White Men Democritus (c. 460 c. 370 BCE) Greece Father of Modern Science (?) First Theory of Atomic Structure (?) Everything is made up of a few simple parts called atomos atomos = uncuttable Shape, size, and structure was responsible for behavior "by convention bitter, by convention sweet, but in reality atoms and void"
The Atom & Dead White Men John Dalton (1766 1844) England Elements made of only one type of identical tiny particles called Atoms Atoms differ by their masses Atoms can not be subdivided, created, or destroyed Atoms from one element can combine with atoms of a different element to make a Compound Atoms are not changed in a chemical reaction, just rearranged
The Atom & Dead White Men Joseph John Thomson (1856 1940) England Discovered the first sub-atomic particle, the Corpuscles (Electron) About 1,840 times lighter than Hydrogen Always the same Negatively charged Won the Nobel Prize 1906
The Atom & Dead White Men Lord Kelvin (1824 1907) Ireland/Scotland Proposed the Plum Pudding model Since atoms were electrically neutral the negatively charged electrons were surrounded by a positively charged spherical cloud Electrons were scattered in the atom like raisins in a plum pudding Age of the Earth 2 x 10 7 to 4 x 10 8 years 4.54 x 10 9 years As Lord Kelvin is the highest authority in science now living, I think we must yield to him and accept his views.
The Atom & Dead White Men Ernest Rutherford (1871 1937) New Zealand/Canada/England Proposed the Nuclear Atom Most of the space in an atom is empty The center of an atom, the nucleus, is small, heavy, and positively charged Electrons orbited the nucleus Suggested the Hydrogen nucleus was a positively charged particle called the proton Theorized that the nucleus also had a non-charged particle, the neutron Won a Nobel Prize in 1908
The Atom & Dead White Men Ernst Mach (1838 1916) Moravia, Austrian Empire, Germany Have you ever seen one? Hecking Ludwig Boltzman Strict Phenomenologist What is real is only observable by the senses Early description of shock-waves Sonic booms are due to compression of pressure waves into one shock-wave which travels at the speed of sound Mach 1
The Atom & Dead White Men Niels Bohr (1885 1962) Denmark/England Proposed the Rutherford Bohr Model Electrons move around the nucleus in fixed orbits The outer orbits have higher energy As electrons fell from outer orbits, they gave off energy The chemical properties of each element was determined by the number of electrons in the outer orbits of its atoms Won a Nobel Prize in 1922
Not All Dead White Men! Aneta Stodolna (1984 -?) Poland Started her PhD in 2009 FOM Institute for Atomic and Molecular Physics, Amsterdam Used a Quantum Microscope and Velocity Map Imaging to visualize the electron s position Published Hydrogen electron photos in 2013 Awarded PhD 2014
What We Know (?) About the Atom Atoms are the smallest unit of an element Elements are different due to the mass of their atoms The mass is mostly in the nucleus The nucleus is the home of positive and neutral particles Negatively charged electrons move around the nucleus in fixed orbits Atoms are have no charge so the number of electrons (-) and protons (+) are equal The chemical properties of each element is determined by the number of electrons in the outer orbits of its atoms
What We Know (?) About the Atom
The Shell Model of the Atom
The Atom Movie
The Making of The Atom Movie
What is an Element? Substance that, when pure, has the same Properties Color State of mater (solid, liquid, gas) at a given temperature Workability ductile vs. malleable vs. shatters hardness Reaction Behavior Combines with Oxygen in same proportion (1:2) Has a unique Symbol Usually from the modern name of the element One or two letters, first one CAPITALIZED
Atomic Symbols Hydrogen - H From Greek for water-former Carbon - C From Latin for coal Oxygen - O From Latin oxys for sharp + genes for begetter Gold Au From Proto-German for to gleam From Latin aurum for gold Strontium Sr From the Scottish Village of Strontian
The Village of Strontian
Abundance in the Universe
The Elements Song Original Version Daniel Radcliffe Version
What We JUST Learned About the (Bohr) Atom Atoms are the smallest unit of an element Elements are different due to the mass of their atoms The mass is mostly in the nucleus The nucleus is the home of positive and neutral particles Negatively charged electrons move around the nucleus in fixed orbits Atoms are have no charge so the number of electrons (-) and protons (+) are equal The chemical properties of each element is determined by the number of electrons in the outer orbits of its atoms
More of What We JUST Learned About the (Bohr) Atom
The Nucleus Protons In the nucleus Positive charge (+) Heavy (1.007 atomic mass unit [u]) Define the element All different elements have different numbers of protons Hydrogen = 1, Carbon = 6, Sulfur = 16, Uranium = 92 Determine the Atomic Number All different elements have different Atomic Numbers Hydrogen = 1, Carbon = 6, Sulfur = 16, Gold = 79, Uranium = 92 1 H, 6 C, 16 S, 79 Au, 92 U
The Nucleus Neutrons In the nucleus Neutral/No charge Heavy (1.009 u) Define the isotope of the element Usually are equal in number to Protons Carbon = 6 protons + 6 neutrons (98.9%) = 12 C Carbon = 6 protons + 7 neutrons (1.1%) = 13 C Carbon = 6 protons + 8 neutrons (<1 x 10-10 %) = 14 C» Radioactive half life 5,730 years
The Shell Model of the (Bohr) Atom
The Orbital Shells Electrons Outside of the Nucleus Occupy discrete areas/energy levels - shells 4 types of shells (s, p, d, h) Negative charge (-) Light (5.486 x 10-4 u) Responsible for chemical bonding Can move between nuclei to form ions Ion is an atom that has more or fewer electrons than protons
The Ion Note that the LOSS of an negatively (-) charged electron makes the resulting ion positive (+) Ions with a positive charge are called cations Ions with a negative charge are called anions
More Ions
You Can t Buy Ions! a cation (+) can t exist without an anion (-)
Mass Number The sum of the number of the protons and neutrons in an atom Examples Hydrogen (H) 1 proton (1) + (0) = 1 ( 1 H) Helium (He) 2 protons & 2 neutrons (2) + (2) = 4 ( 4 He) Carbon (C) 6 protons & 6 neutrons (6) + (6) = 12 ( 12 C) Uranium (U) 92 protons & 146 neutrons (92) + (146) = 238 ( 238 U) 238 U, most common isotope, half life of 4.47 x 10 9 years
Atomic Weight The average sum of the mass of the protons, neutrons, and electrons in an atom Average includes different isotopes Examples Hydrogen (H) 1 proton, 1 electron (1 x 1.007u) + (0 x 1.009u) + (1 x 5.486 x 10-4u) = 1.0075u (1.0080u) Helium (He) 2 protons, 2 neutrons, 2 electrons (2 x 1.007u) + (2 x 1.009u) + (2 x 5.486 x 10-4u) = 4.003u (4.003u) Carbon (C) 6 protons, 6 neutrons, 6 electrons (6 x 1.007u) + (6 x 1.009u) + (6 x 5.486 x 10-4u) = 12.099u (12.011u) Uranium ( 238 U) 92 protons, 146 neutrons, 92 electrons (92 x 1.007u) + (146 x 1.009u) + (92 x 5.486 x 10-4 u) = 240.01u (238.03u) 238 U, most common isotope, half life of 4.47 x 10 9 years
The Fully Tricked Out Atomic Symbol
Three Truths and a Lie Dmitri Mendeleev (1834-1907) Russian Set the standard for Russian Vodka at 40% Ethanol Wrote the Russian Textbook Principles of Chemistry 1 st edition 1868 13 th edition 1947 Avid Solitaire player
Mendeleev s Law Chemical and Physical properties of the elements recur periodically when the elements are arranged in the order of their Atomic Weights or When the elements are arranged in order of their masses their properties repeat Li behaves like Na, Na behaves like K Li (6.94u) weighs less than Na (23.0u), Na weighs less than K (39.1u)
Mendeleev s Law Fluorine behaves like Chlorine, Chlorine behaves like Bromine F (19.00u) weighs less than Cl (35.45u), Cl weighs less than Br (79.91u)
Mendeleev s Law 6.94u 19.00u 22.99u 35.45u 39.10u 79.91u
Mendeleev s Table 2/17/1869
Mendeleev s Periodic Table 1871
Modern Periodic Table 2013
The Periodic Table
The Periodic Table Horizontal Rows are called Periods Left to Right Mass increases slowly Properties change metals metalloids non-metals Nobel gasses Vertical Columns are called Groups Top to Bottom Mass increases rapidly Properties remain similar Alkali Metals (Li, Na, K, etc.) highly reactive form 1 + ions Alkaline Earth Metals (Be, Mg, Ca, etc.) very reactive form 2 + ions Halogens (F, Cl, Br, etc.) low boiling temperatures form 1 - ions Noble Gasses (He, Ne, Ar, etc.) Very unreactive form NO ions
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My Favorite Periodic Table
What REALLY Matters?
Next Week Chemical Bonding Ionic Covalent Simple Chemical Structures & Names