Updated October 2006 Created by C. Ippolito September 2006 Elements, Atoms, and the Periodic Table Unit Objectives: 1.Identify the names, symbols and origin of chemical elements; 2.Appreciate relative abundance of various elements; 3.Identify the different kinds of elements represented in the periodic table; 4.Recognize the major properties used to distinguish the different types of elements; 5.Appreciate the historical development of the atomic theory; 6.Explain and describe the atomic structure of elements and how it relates to their individual properties

Updated October 2006 Created by C. Ippolito September 2006 Elements: Ancient and Modern Theory Robert Boyle – “The Sceptical Chymist” Element –Substance that cannot be broken into simpler substances Compound –Formed when two or more elements combine Antoine Lavoisier ( ) –1789 – “Elementary Treatise on Chemistry” Identified 33 “elements”

Updated October 2006 Created by C. Ippolito September 2006 Chemical Symbols alchemists used secret codes –signs for known elements shorthand used to represent elements –JJ Bersalius each element is represented a one or two letter symbol with the first letter always capitalized symbol derived from first letter of name, if already assigned take a second letter from name

Updated October 2006 Created by C. Ippolito September 2006 Chemical Names and Symbols English named –aluminum (Al) –argon (Ar) –arsenic (As) –carbon (C) –calcium (Ca) Honorary named –Curium (Cm) –Californium (Cf) Latin named –gold [aurum] (Au) –iron [ferrum] (Fe) –lead [plumbum] (Pb) –mercury [hydragyrum] (Hg) –silver [argentum] (Ag) –sodium [natrium] (Na) –tin [stannum] (Sn) German named –tungsten [wolfram] (W)

Updated October 2006 Created by C. Ippolito September 2006 Abundant and Rare Elements 11 elements form 99% of earth crust - oxygen - silicon - aluminum - iron - calcium - sodium - potassium - magnesium - hydrogen - titanium - chlorine

Updated October 2006 Created by C. Ippolito September 2006 Periodic Table of Elements metals metalloids nonmetals

Updated October 2006 Created by C. Ippolito September 2006 Organization of Periodic Table Rows –form periods Columns –form groups or families Classroom Table –RED gaseous elements –BLUE liquid elements –BLACK solid elements

Updated October 2006 Created by C. Ippolito September 2006 Metals Physical Properties – solid, except Hg –Conductivity good conductors of heat and electricity –Luster shiny surface –Malleability may be hammered or rolled –Ductility may be drawn into wires –Hardness varies –hard – Cr, Fe, Mn –soft – Au, Pb, Na

Updated October 2006 Created by C. Ippolito September 2006 Nonmetals Physical Properties – solid, liquid, gas –Conductivity poor conductors of heat and electricity –Luster NONO, dull surface –Malleability NONO, brittle – crumble when hit –Ductility NONO –Hardness NONO –carbon (diamond) exception

Updated October 2006 Created by C. Ippolito September 2006 Metalloids some properties like metals others like nonmetals –semiconductors

Updated October 2006 Created by C. Ippolito September 2006 Early Atomic Structure Democritus –A–A–A–Atomic Theory of Matter all matter could be divided into tiny indivisible particles called a aa atoms different types of atoms existed for each different type of material not based on experimental evidence Aristotle –C–C–C–Continuous Theory of Matter all matter was continuous and always could be divided into smaller parts without end

Updated October 2006 Created by C. Ippolito September 2006 Law of Conservation of Mass Antoine Lavoisier –F–F–F–Father of Modern Chemistry quantitatively measured mass of reactants and compared it with mass of products found mass remained constant –L–L–L–Law of Conservation of Mass matter can be changed but cannot be created nor destroyed combustion combines elements with oxygen

Updated October 2006 Created by C. Ippolito September 2006 Law of Definite Proportions Joseph Proust –r–regardless of where a substance came from or how large the sample –s–specific substances always contained elements in the same ratio by mass Law of Definite Proportions

Updated October 2006 Created by C. Ippolito September 2006 Dalton’s Atomic Theory John Dalton –p–postulates to explain Lavoisier’s and Proust’s findings 1.Matter made of small particles (atoms) 2.Atoms are indestructible. Cannot be created or destroyed in chemical or physical changes. 3.Atoms of same element are identical, have the same mass. 4.Atoms of different elements are different, have different mass 5.Compounds form by combining atoms of different elements

Updated October 2006 Created by C. Ippolito September 2006 Parts of the Atom in the late 1800’s experiments show that atoms are made of smaller particles –E–E–E–Elementary or S SS Subatomic Particles proton – positive charge, mass = 1 amu, in nucleus electron – negative charge, mass = 1/1837 amu, outside nucleus neutron – neutral charge, mass = 1 amu, in nucleus

Updated October 2006 Created by C. Ippolito September 2006 Elements and Isotopes Isotope –atoms of the same element that have different mass same atomic number –same number of protons and electrons –same behavior mass differs because the atoms have different numbers of neutrons Isotopes of Hydrogen –Protium 1 1 H –Deuterium 2 1 H –Tritium 3 1 H

Updated October 2006 Created by C. Ippolito September 2006 Atomic Masses for an individual atom is a whole number –atomic mass = # of protons + # of neutrons for an element it is the average of the atomic masses of all existing isotopes –in periodic table it is a decimal value Calculation of Element Atomic Mass –(isotope mass)x(abundance) = mass contribution –add mass contributions of all isotopes –resulting sum is the average atomic mass

Updated October 2006 Created by C. Ippolito September 2006 Mole the mole is a fixed amount of particles –1 mole = x pieces –this number is N or Avogadro’s Number named in honor of an Italian chemist the concept of the mole allows us to set up a relationship between the immeasurable masses of atoms (in amu) and measurable amounts of a substance (in grams) –1 mole of amu’s = 1 gram