Periodic Table Chapter 6 What do I know? • On the back of the blank periodic table write down at least 3 pieces of information you can get from the periodic table. Page 2 3/15/2016 A Brief History… • Joseph Proust • Law of Definite Composition – elements combine in definite proportions by weight • The weight of one element that combines with the weight of another element = combining weight Page 3 3/15/2016 • Joseph Berzelius • [1807 - 1818 ] • Determined the combining weights of 43 elements with oxygen. • Recognized similarities of certain elements... – similar metallic properties – similar reactive properties – Li, Na, K – similar nonmetals – Cl, Br, I, • “TRIPLETS” Page 4 3/15/2016 • Johann Wolfgang Dobereiner • 1829 • mathematician • discovered that combining weight of middle triplet is the average [or near average]of the combining weights of the other two • Li, Na, K Page 5 3/15/2016 • Jean Stas • 1860 • confirmed Proust theory of definite composition • established accurate atomic weight of the known elements Page 6 3/15/2016 Was there a relationship between the weight of an element and its properties? • John A.R. Newlands • 1865 • arranged elements in order of atomic weight • elements with similar properties were 7, or multiple of 7 apart • Law of Octaves Page 7 3/15/2016 Dimitri Mendeleev 1869 • developed a chart -listed elements by increasing atomic weight • grouped elements with similar properties in the same row • Left Gaps where no element fit the pattern. • Predicted discovery of new elements • Predicted properties of new elements Page 8 3/15/2016 Mendeleev’s Table Page 9 3/15/2016 Page 10 3/15/2016 Old Periodic Law . “The properties of elements are in periodic dependence of their atomic weights.” Dimitri Mendeleev Page 11 3/15/2016 ALTERATIONS and ADDITIONS • Sir Wm.Ramsay • 1890’s • Discovered Ne, Ar, Kr, Xe • Helium and Radon disc. Previously • New row added to Periodic Table Page 12 3/15/2016 • • • Henry Gwyn-Jeffreys Mosley 1914-1915 Number of protons determined – atomic number - identifies what an element is • Periodic Table Rearranged – elements arranged by increasing atomic number – similar elements put in columns instead of rows Page 13 3/15/2016 Modern Periodic Law • “The properties of elements are in periodic dependence of their atomic numbers.” Page 14 3/15/2016 ARRANGEMENT OF THE MODERN PERIODIC TABLE • A horizonal row on the periodic chart is refered to as either a period, or a series. • A vertical column on the periodic chart is refered to as either a group, or a family. Page 15 3/15/2016 Element • H • Li Location on Chart Grp 1 Grp 1 • Na Grp 1 Na . • K Grp 1 K. • Rb Grp 1 Rb . • Cs Grp 1 Cs . • Fr • Grp 1 Fr . Page 16 Electron Dot Notation H. Li . Alkali Metals Properties Colorless gas Soft; silver highly reactive Soft; silver highly reactive Soft; silver highly reactive Soft; silver highly reactive Soft; silver highly reactive Soft; silver most reactive metal 3/15/2016 Element • Be • Mg • Ca • Sr • Ba • Ra Page 17 Location on Chart Grp 2 Electron Dot Notationc Be : Properties Reactive metal Grp 2 Mg : Reactive metal Grp 2 Ca : Reactive metal Grp 2 Sr : Reactive metal Grp 2 Ba : Reactive metal Grp 2 Ra : Most reactive metal of group Alkaline Earth Metals 3/15/2016 What pattern(s) do we see? • All elements in groups have same electron dot structure. • Group placement predicts valence. • Groups usually have similar properties. • Most reactive metals at the bottom of the group. Page 18 3/15/2016 Element • B • Al • Ga • In • Tl Page 19 Location on Chart Electron Dot Notation Properties Grp 3 B: nonmetal; black solid Grp 3 Al: Metal Grp 3 Ga : Metal Grp 3 In : Metal Grp 3 Tl : Most reactive metal 3/15/2016 Element Location on Chart Electron Dot Notation Properties • C Grp 4 C: black→clear solid Grp 4 Si : Metalloid Grp 4 Ge : Metal Grp 4 Sn : Metal Grp 4 Pb : Most reactive metal • Si • Ge • Sn • Pb Page 20 3/15/2016 Element • • • • • • • • • • Location on Chart Electron Dot Notation Properties N Grp 5 N: gas; nonmetal Grp 5 P: nonmetal Grp 5 As : Metalloid Grp 5 Sb : Metalloid Grp 5 Bi : Metal P As Sb Bi Page 21 3/15/2016 Element • O • • • • • • • • • S Se Te Po Page 22 Location on Chart Electron Dot Notation Properties Grp 6 O: gas; nonmetal reactive Grp 6 S: Nonmetal Grp 6 Se : Nonmetal Grp 6 Te : Nonmetal Grp 6 Po : Metal Chalcogen Family 3/15/2016 Element • • F • • Cl • • Br Location on Chart Grp 7 • • I • • At Electron Dot Notation :F: gas; most reactive nonmetal Grp 7 :Cl : gas; reactive nonmetal Grp 7 :Br : liquid; reactive Grp 7 :I: solid; reactive nonmetal Grp 7 :At : solid; reactive nonmetal Halogen Family Page 23 Properties nonmetal 3/15/2016 Element • • • • • • • • • • • He Ne Ar Kr Xe Rn Page 24 Location on Chart Electron Dot Notation Properties Grp 8 He : inert; nonmetal Grp8 :Ne : inert; nonmetal Grp 8 :Ar : inert; nonmetal Grp 8 :Kr : inert; nonmetal Grp 8 :Xe : inert; nonmetal Grp 8 :Rn : inert; nonmetal Noble Gases / Inerts 3/15/2016 What pattern(s) do we see? • All elements in groups have same • • • • electron dot structure. Group placement predicts valence. Groups usually have similar properties – (exception: steps) Most reactive nonmetals at the top of the group. Most reactive metals at the bottom of the group. Page 25 3/15/2016 I spy with my little eye an element with… • 3 energy levels and 2 valence electrons • Mg • 5 energy levels and 4 valence electrons • Sn • 2 energy levels and 8 valence electrons • Ne • 1 valence electron and 5 energy levels • Rb • 1 valence electron and 7 energy levels • Fr Page 26 3/15/2016 I spy with my little eye an element with… • 4 energy levels and 7 valence electrons • Br • 3 energy levels and 5 valence electrons • P • 2 valence electrons and 4 energy levels • Ca • 3 valence electrons and 2 energy levels • B • 8 valence electrons and 5 energy levels • Xe Page 27 3/15/2016 I spy with my little eye an element with… • The heaviest halogen… • At (astatine) • The triplet with the average atomic weight of 35.5… • Cl • The least reactive Chalcogen • Po (polonium) • The group that fills the s2 valence orbital • Alkaline Earth Metals • A third period metalloid • Si Page 28 3/15/2016 Bonding • See interactive Page 29 3/15/2016 Types of Bonding • Ionic – Electrons transfer from one atom to another creating + and – ions. • Covalent – Atoms share electrons to create a molecule. • Metallic – Many atoms share electrons Page 30 3/15/2016 Types of Bonding • Ionic – Electrons transfer from one atom to another – creating + and – ions. e+ Page 31 - + energy 3/15/2016 Ionization Energy • The energy required to remove the outermost e- in an atom. Ionization Energy Ionization Energy (kJ/moL) Helium 2500 Neon 2000 Argon 1500 Hydrogen Series1 1000 500 0 Lithium Sodium 0 10 20 30 40 Atomic Number Page 32 3/15/2016 Page 33 3/15/2016 • Why are some e- removed more easily? – Electrons that are farther away from the nucleus and that have more E levels between them and the nucleus • Low ionization energy – characteristic of METALS. • High ionization energy – characteristic of NONMETALS. • Removing successive electrons is more difficult, but follows the same overall pattern. • Na + Energy Na+ + e• Na+ + Energy Na++ + e• Na+++ Energy Na++++ e- Page 34 119 Kcal / mol 1090 Kcal/ mol 1652 Kcal/ mol 3/15/2016 Electron Affinity The energy released / absorbed when an electron is accepted by a neutral atom e+ Ionization E removes eand forms + ion Page 35 linked - + energy Electron affinity is the E released when the neutral atom accepts the freed eand becomes - 3/15/2016 Electron Affinity Electron Affinity (kJ/moL) Electron Affinity 100 Lithium 0 -100 0 Sodium 10 20 30 40 Series1 -200 -300 -400 Fluorine Chlorine Atomic Number Page 36 3/15/2016 Electron Affinity Increases across a period D e c r e a s e s Page 37 3/15/2016 • For atoms that have - valences: Atom + e- A- + E exothermic - energy released (electron affinity) stable product Atom + e- + E Aendothermic - energy required unstable product • • • • • • • Page 38 3/15/2016 • Covalent – Atoms share electrons to create a molecule. -’ Shared e s Page 39 3/15/2016 Electronegativity • the attraction of an atom for a shared pair of electrons Page 40 3/15/2016 Electronegativity Electronegativity Electronegativity 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 Fluorine Chlorine Series1 Lithium 0 Sodium 10 20 30 40 Atomic Number Page 41 3/15/2016 Table of Electronegativities Page 42 3/15/2016 Electronegativity • Types of Covalent Bonds: • pure covalent - relatively even sharing of e• polar covalent - uneven sharing of e• 0 - .5 ....... pure covalent .5 - 1.7..... polar covalent > 1.7 ....... ionic bond • • • Page 43 3/15/2016 Atomic Radius [size] Atomic Radius Atomic Radius (pm) 250 200 Lithium 150 Sodium 100 Series1 Chlorine Fluorine 50 0 0 10 20 30 40 Atomic Number Page 44 3/15/2016 Atomic Radius [size] Page 45 3/15/2016 • Down a group – • Across a period – • • E levels are added. Increased attraction between the E levels and the nucleus causes the size to decrease. Pauli Repulsion Theory As the number of electrons increases so does the repulsion between the electrons; this may help account for the irregular increase in the radii. Page 46 3/15/2016 Ions [size] • Increases down a Group • Decreases across a Period • Metal atoms lose electrons – become positive (cation) – Cations are SMALLER than the atoms from which they come. • Nonmetal atoms gain electrons – become negative (anion) – Anions are LARGER than the atoms from which they come. Page 47 3/15/2016 Density Density (g/cm^3) Density 10 9 8 7 6 5 4 3 2 1 0 -1 0 Boron Lithium Series1 Aluminum Sodium Chlorine 10 Fluorine20 30 40 Atomic Number Page 48 3/15/2016 Density • Here the density of each period is graphed individually Page 49 3/15/2016 Page 50 3/15/2016 Density • Generally, density – increases down a group – Increases across the metals in a period, and then decreases across the nonmetals Page 51 3/15/2016 M.P and B.P. Melting Point/Boiling Point 3500 3000 Temperature °C 2500 2000 Melting Point 1500 Boron 1000 Boiling Point Aluminum 500 0 0 Lithium -500 5 10 Neon 15 Sodium 20 Argon25 30 35 40 Atomic Number Page 52 3/15/2016 M.P. and B.P. • Generally, like density, M.P. and B.P. – increases down a group – Increases across the metals in a period, and then decreases across the nonmetals Page 53 3/15/2016 Configurations and the Periodic Table • Electrons that reside in the outermost shell of an atom are called valence electrons. – These electrons are primarily involved in chemical reactions. – Elements within a given group have the same “valence shell configuration.” – This accounts for the similarity of the chemical properties among groups of elements. Page 54 3/15/2016 Configurations and the Periodic Table • The following slide illustrates how the periodic table provides a sound way to remember the Aufbau sequence. – In many cases you need only the configuration of the outer electrons. – You can determine this from their position on the periodic table. – The total number of valence electrons for an atom equals its group number. Page 55 3/15/2016 Configurations and the Periodic Table s2 p6 s1 1 s2 p1 p2 p3 p4 p5 2 3 S 4 filling d1 d2 d3 d4 d5 d6 d7 d8 d9 d10 3d P filling 4d 5 6 * 7 ** 5d 6d f filling Page 56 3/15/2016 The Elements • The Elements in Song Page 57 3/15/2016