CHM 1210 1st Edition Lecture 5 Outline of last lecture I. Atoms, Ions and Molecules a. The Rutherford Model of Atomic StructureOutline of current LectureII. Atoms, Ions and Moleculesa. Navigating the periodic Tableb. The Masses of ions, atoms and moleculesc. Moles and Molar massCurrent Lecture:2.3 Navigating the Periodic Table In 1872, the Russian chemist Dmitri Mendeleev (1834-1907) published the forerunner of the modern periodic table of elements -Ordered elements by _______atomic mass____ -Arranged elements in columns based on similar _______chemical and physical properties Left ___open spaces ____in the table for elements not yet discovered Definition: The modern periodic table of the elements = A chart of the elements in order of their atomic numbers and in a pattern based on their ____atomic #_______ Obs: -The modern periodic table of elements has -Horizontal rows: Called __periods____ (1 → 7) -Columns: Contain elements of the same ___family or groups___(1 →18) -Several groups have names as well as numbers. Definition: Radionuclide = a __radioactive or unstable__ nuclide. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Obs: -Most of the nuclides of the actinide elements are _____radioactive, i.e., radionucleons ____. -Elements with Z > 94 (in the actinides series) are highly ___radioactive _____. Thus, they are not found __in nature ____, but can be ____synthesized by chemist __. Metals a. Are located on ___left side of zig zag line____ in the periodic table Exception: __hydrogen ____ b. Represent the largest category of elements c. Properties: oSolids at room temperature (except for Hg) oMost metals have a silvery shine oMalleable (pounded into flt sheets)oDuctile (can be twisted into wire)oConduct heat and electricity Nonmetals a. Are located on ____right side of zig zag line_____ b. in the periodic table. c. Are present in a relatively small number d. Properties: oGases (11), liquids (1), or solids (5) oNone of the nonmetals are silvery in appearance but they are in general brightly colored • Solid nonmetals are brittle oPoor conductors of heat and electricity Semimetals (metalloids) a. Are located _along zig zag line__ in the periodic table. b. 7 elements c. Properties fall between those of the metals and nonmetals groups : oSolids at room temperature oMost of them are silvery in appearance oBrittle oPoor conductors of heat and electricity2.4 The Masses of Atoms, Ions and Molecules Definitions: Average Atomic Mass = __weighted average ___of the isotopic masses of the element’s __naturally occurring isotopes _____. = the average atomic mass of element X �1, �2, �3, … = the masses of the element X’s isotopes �1, �2, �3, … = the natural abundances of the element X’s isotopes Natural Abundance = the fraction/proportion of a particular isotope, usually expressed as a _percentage ____, relative to all the isotopes for that element in a natural sample. Practice problem: What is the average atomic mass of the element neon? Average atomic mass of neon = ( 19.9924* 90.4838/100 )+( 20.9940* .2696/100 )+( 21.9914* 9.2465/100 )= 20.1799amu Definitions: Molecular mass = the mass in amu of one molecule of a _covalent or molecular compound(2_non metals_ Crystals of sodium chloride Formula unit (ionic compounds) = the smallest electrically neutral unit of _an ionic compounds __ Formula mass = the mass in amu of one formula unit of __an ionic compound___ Practice problems: a. What is the molecular mass of SO2? (1*32.065amu)+ (2*15.999amu)=64.063Amu b. What is the formula mass of CaCl2?(1*40.08)+( 2*35.454)= 110.984amu 2.5 Moles and Molar Mass Definitions: Mole (mol) = an amount of substance that contains __avagadros number of particles _ Avogadro’s number (NA) = the number of carbon atoms in exactly 12 grams of the carbon-12 isotope. NA is the number of particles in one mole. NA = __6.0221 * 10^23 particles____ Obs: Mole is a convenient unit for expressing macroscopic quantities (atoms or molecules) involved in macroscopic processes we observe. Practice problem: The U.S. pennies minted before 1960 each contained about 2.4 x 1022 atoms of Cu. How many moles of Cu are in such a penny? 2.4*10^22 atoms of