# Mullis1 The Periodic Table  Elements are arranged in a way that shows a repeating, or periodic, pattern.  Dmitri Mendeleev created the first periodic.

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Mullis1 The Periodic Table  Elements are arranged in a way that shows a repeating, or periodic, pattern.  Dmitri Mendeleev created the first periodic table of the elements in 1869.  He ordered the ~70 known elements by their atomic masses and their chemical properties.  He found that some elements could not be put into groups with similar properties and at the same time stay in order.

Mullis2 Modern Periodic Table  Later, Henry Moseley carried on the work. Moseley put the elements in order of increasing atomic NUMBER. He found that the position of the element corresponded to its properties.  The modern periodic table shows the position of the element is related to : Atomic number AND Arrangement of electrons in its energy levels

Mullis3 Atomic Sizes using Periodic Table  As we move down a group, atoms become larger. Larger n = more shells = larger radius  As we move across a period, atoms become smaller. More protons = more effective nuclear charge, Zeff More positive charge increases the attraction of nucleus to the electrons in the outermost shell, so the electrons are pulled in more “tightly,” resulting in smaller radius

4 Ionization energy  Ionization energy of an ion or atom is the minimum energy required to remove an electron from the ground state of the isolated gaseous atom or ion.  The first ionization energy, I 1 is the energy required to remove one electron from an atom. Na(g)  Na + (g) + e -  Larger ionization energy, harder to remove electron.

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6 Periodic Trends in Ionization Energy  Highest = Fluorine  Ionization energy decreases down a group. Easier to remove electrons that are farther from the nucleus.  Ionization energy increases across a period. Zeff increases, so it’s harder to remove an electron.

7 Electron Affinity  Electron affinity is the energy change when a gaseous atom gains an electron to form a gaseous ion.  Electron affinity: Cl(g) + e -  Cl - (g)  Ionization energy: Cl(g)  Cl + (g) + e - Gain Lose

8 Electronegativity  Electronegativity is the ability of an atom in a compound to ATTRACT an electron.  F has the highest electronegativity.  (She is “SO ATTRACTIVE!”)

9 Metals  Metallic character increases down a group and from left to right across a period.  Metal properties: Lustrous (shiny) Malleable (can be shaped) Ductile (can be pulled into wire) Conduct electricity  Metal oxides form basic ionic solids: Metal oxide + water  metal hydroxide  Metal oxides react with acids to form salt and water

10 General Trend Summary Electronegativity, Ionization Energy, Electron Affinity Electronegativity, Ionization Energy, Electron Affinity F Atomic Radius, Metallic Character Atomic Radius, Metallic Character Fr

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Mullis12 Ionization energy  Ionization energy of an ion or atom is the minimum energy required to remove an electron from the ground state of the isolated gaseous atom or ion.  The first ionization energy, I 1 is the energy required to remove one electron from an atom. Na(g)  Na + (g) + e -  The 2 nd ionization energy, I 2, is the energy required to remove an electron from an ion. Na + (g)  Na 2+ (g) + e -  Larger ionization energy, harder to remove electron.

Mullis13 Periodic Trends in Ionization Energy  Highest = Fluorine  Ionization energy decreases down a group. Easier to remove electrons that are farther from the nucleus.  Ionization energy increases across a period. Zeff increases, so it’s harder to remove an electron. Exceptions: Removing the 1 st and 4 th p electrons

Mullis14 Electron Affinity  Electron affinity is the energy change when a gaseous atom gains an electron to form a gaseous ion.  Electron affinity: Cl(g) + e -  Cl - (g)  Ionization energy: Cl(g)  Cl + (g) + e - Gain Lose

Mullis15 Electronegativity  Electronegativity is the ability of an atom in a compound to ATTRACT electrons.  Fluorine has the highest electronegativity.  Fluorine is “SO ATTRACTIVE!” (bats eyelashes)

Mullis16 Metals  Metallic character increases down a group and from left to right across a period.  Metals are found to the left of the zig-zag line on the periodic table.  Metal properties: Lustrous (shiny) Malleable (can be shaped) Ductile (can be pulled into wire) Conduct electricity  Metals form cations (positive ions) This means they lose 1-4 electrons Therefore, they are usually found in IONIC compounds

Mullis17 Nonmetals  Lower melting points than metals  Diatomic molecules are nonmetals.  The seven (7) diatomic molecules are: Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2  Two or more nonmetals form molecular compounds with COVALENT bonds.

Mullis18 Trends See your book for full explanation. Closer to F = more  ELECTRONEGATIVITY  ELECTRON AFFINITY  IONIZATION ENERGY Closer to Cs = more  METALLIC CHARACTER  ATOMIC RADIUS  REACTIVITY

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