Periodic Table - Lecture note week1 PDF

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Periodic Table  

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Element: a fundamental substance that cannot be chemically changed or broken down into anything simpler There are 118 elements: o 90 naturally occurring  83 of the 90 naturally occurring elements are found in reasonable abundance on earth  Others like Francium (Fr) are more rare – there is less than 20 grams on the entire Earth at any given time o 28 artificially produced The first element to be discovered in several thousand years was Arsenic (1250) Chemical and physical properties: o John Dobereiners observation in 1829 there were triads that appeared to be similar o Property – any characteristic that can be used to describe or identify matter o Intensive properties: values that do not depend on the amount of substance o Extensive properties: depend on the amount of substance o Physical properties: do not involve a change in chemical makeup o Chemical properties: Involve a change in chemical makeup Modern periodic table o Dmitri Mendeleev – 1869  7 horizontal rows called Periods  18 vertical columns called Groups o Elements in a given group have similar properties o But there are actually 32 groups:  The Lanthanides and Actinides Groupings o 2 larger groups on the left and 6 larger groups on the right are called the main groups  Most of the elements on which life is based o 10 smaller groups in the middle are transition metal groups o 14 groups at the bottom are the inner transition metal groups Metals o left side of the table o Bound on the right by a zigzag line from Boron to Astatine o All except mercury are solid at room temperature o Silvery shine o Malleable rather than brittle o Good conductors of heat and electricity Nonmetals o Except H nonmetals are on the right side of the table o At room temperature 11 of 17 are gasses, 1 liquid (Br), 5 solids (C, P, S, Se, I) o Not silvery o Can be brightly colored o Brittle and not malleable o Poor heat and electrical conductors Metalloids o Border between metals and nonmetals o Zigzag pattern on the periodic table o Properties are similar to their metallic and nonmetallic counterparts o Most are silvery and solid

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o Brittle not malleable o Poor conductors of heat and electricity Group 1A – Alkali metals o Soft silvery metals o React rapidly and violently with water o Products of reactions with water are very basic (hence the name alkali metals) o Not found in nature as a pure state but in combination with other elements Group 2A – Alkali Earth metals o Lustrous, shiny metals o Less reactive than Group 1A o Not found in a pure state but in combination with other elements Group 7A – Halogens o Colorful and corrosive nonmetals o Found in nature only in combination with other elements – commonly with Alkali metals Group 8A – Noble Gasses o Colorless gasses with very low chemical reactivity o He and Ne don’t combine with any other element o Argon and Krypton and xenon combine with very few Periodic properties o atomic radius:  Within a period, there is a regular decrease in atomic radius with increasing atomic number  Within a group, there is a regular increase in atomic radius with increasing atomic number o Electron affinity: the energy evolved when an atom or ion that gains an electron.  Electron affinity increases up and to the right of the periodic table (chlorine has the highest electron affinity) o Electronegativity: a ranking of the tendency of an atom to gain an electron  Electronegativity increases up and to the right of the periodic table (fluorine is defined to have the highest electronegativity value: 3.97) o Ionization energy: the quantity of energy required to remove a specific electron from an atom, ion, or molecule  Ionization energy decreases within a family  with increasing atomic size  with increasing distance between the electron to be removed and the nucleus  with a decrease in number of electrons in the outer shell  with the introduction of a new sublevel  with the addition of an electron to a half-filled sublevel  with the addition of inner shell electrons that increase repulsion of outer shell electrons...