VWT 272 Class 3 Quiz 1 Number of quizzes taken 27 Min 11 Max 30 Mean 21.3 Median 21 Mode 21
Lecture 3 The Periodic Table and the Molecule Once we understand how molecules are formed, we can manipulate them. If you can manipulate molecules, you can manipulate genes and matter, you can synthesize new material - the implications are just unbelievable. Ahmed Zewali (1946 -?)
Plan of Study Review of the Atom The Periodic Table The Molecule Ionic Bonds Covalent Bonds
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
List of the Elements
Abundance in the Universe
The Elements Song Tom Lehrer Version Daniel Radcliffe Version
What We 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
What We 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 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 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
Chemistry is the Search for Nobility The nobility of the ancients was no more than purity and serenity; what need for bushels of emblems? - Zen Proverb
Chemistry is the Search for Nobel-ity
Chemistry is the Search for Nobel-ity
Chemistry is the Search for Nobility
The Periodic Table
Neon (Ne) Noble Gasses
Argon (Ar) Noble Gasses
The Octet Principle Gilbert Lewis (1875-1949) American In chemical compounds, atoms tend to have the electron configuration of a noble gas. Coined The Rule of 8 There are 8 valence electrons in most atoms in chemical compounds Nominated 35 times for a Nobel Prize
The Octet Principal Noble Gasses have a Full outer shell 8 electrons in 4 pairs Except H and He which have an outer shell of 2 electrons Outer electrons called Valence Electrons Lewis Dot Structure of Ne
Lewis Dot Structures More Lewis Dot Structures
You Can t Buy Ions! a cation (+) can t exist without an anion (-)
Opposites Attract Ionic Bonding Na + Cl Na + + Cl - NaCl
Opposites Attract Ionic Bonding Na + Cl Na + + Cl - NaCl
Opposites Attract Ionic Bonding Is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. (Wikipedia)
Opposites Attract Ionic Bonding Mg + Cl + Cl Mg 2+ + Cl - + Cl - MgClCl Mg + 2Cl Mg 2+ + 2Cl - MgCl 2
Opposites Attract Ionic Bonding Examples Sodium bromide - NaBr Potassium Chloride KCl Calcium Chloride CaCl 2 Magnesium Oxide MgO Metals to Nonmetals
Sharing is Caring Covalent Bonding Cl + Cl ClCl Cl 2
Sharing is Caring Covalent Bonding Cl + Cl ClCl Cl 2
Sharing is Caring Covalent Bonding Examples Hydrogen Cloride HCl Oxygen Dihydroxide H 2 0 Methane - CH 4 Nonmetals to Nonmetals
Sharing is Caring Covalent Bonding Examples H + Cl HCl
Sharing is Caring Covalent Bonding Examples 2H + O H 2 O
Sharing is Caring Covalent Bonding Examples 4H + C CH 4
The Worst Bond Movie Ever!
Next Week Chemical Nomenclature Introduction to Acids and Bases ph and TA
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