Topic Trends in the Periodic Table Ionization Energy

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Topic: Trends in the Periodic Table: Ionization Energy and Electronegativity Do Now: p. 13

Topic: Trends in the Periodic Table: Ionization Energy and Electronegativity Do Now: p. 13 #1 -5

Trends • more than 20 properties change in predictable way based location of elements

Trends • more than 20 properties change in predictable way based location of elements on PT • some properties: - anyone know where we can find these numbers? ! – Density – melting point/boiling point – atomic radius – ionization energy – electronegativity

REVIEW: How do you know if an atom gains or loses electrons? • Think

REVIEW: How do you know if an atom gains or loses electrons? • Think back to the Lewis structures of ions • Atoms form ions to get a valence of 8 (or 2 for H) • Metals tend to have 1, 2, or 3 valence electrons – It’s easier to lose them • Nonmetals tend to have 5, 6, or 7 valence electrons – It’s easier to add some

OR

OR

Ionization Energy • the amount energy required to remove a valence electron from an

Ionization Energy • the amount energy required to remove a valence electron from an atom in gas phase • 1 st ionization energy = energy required to remove the most loosely held valence electron (e- farthest from nucleus) = found on table S

previous | index | next • Cs valence electron lot farther away from nucleus

previous | index | next • Cs valence electron lot farther away from nucleus than Li • electrostatic attraction much weaker so easier to steal electron away from Cs • THEREFORE, Li has a higher Ionization energy then Cs

Increased Ionization Energy (harder to remove an electron) Decreased Ionization Energy (easier to remove

Increased Ionization Energy (harder to remove an electron) Decreased Ionization Energy (easier to remove an electron)

Electronegativity • ability of atom to attract electrons in bond • noble gases tend

Electronegativity • ability of atom to attract electrons in bond • noble gases tend not to form bonds, so don’t have electronegativity values • Unit = Pauling • Fluorine: most electronegative element = 4. 0 Paulings

Decreased Ionization Energy (easier to remove an electron) Increased Electronegativity Increased Ionization Energy (harder

Decreased Ionization Energy (easier to remove an electron) Increased Electronegativity Increased Ionization Energy (harder to remove an electron) Decreased Electronegativity

Reactivity of Metals • judge reactivity of metals by how easily give up electrons

Reactivity of Metals • judge reactivity of metals by how easily give up electrons (they’re losers) • So the easier it is to remove an electron the more reactive – Lower ionization energy = more reactive = more metallic

Increased Ionization Energy (harder to remove an electron) More metallic Decreased Ionization Energy (easier

Increased Ionization Energy (harder to remove an electron) More metallic Decreased Ionization Energy (easier to remove an electron) Decreased Electronegativity Increased Electronegativity Most reactive metal = Fr (the most metallic)

Reactivity of Non-metals • judge reactivity of non-metals by how easily gain electrons (they

Reactivity of Non-metals • judge reactivity of non-metals by how easily gain electrons (they are winners) • So the greater the affinity for electrons, the more reactive – Higher electronegativity= more reactive

Decreased Ionization Energy (easier to remove an electron) Decreased Electronegativity Increased Ionization Energy (harder

Decreased Ionization Energy (easier to remove an electron) Decreased Electronegativity Increased Ionization Energy (harder to remove an electron) More metallic Most reactive metal = Fr (the most metallic) Most Reactive Nonmetal N o =F n r e a c t i v e Nonreactive BACK

Allotropes • Different forms of element in same phase – different structures and properties

Allotropes • Different forms of element in same phase – different structures and properties • O 2 and O 3 - both gas phase – O 2 (oxygen) - necessary for life – O 3 (ozone) - toxic to life • Graphite, diamond: – both carbon in solid form