Periodic Properties

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Periodic Properties

• Chapter 7

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Periodic Properties

• Periodic Properties Properties that depend on
  an elements position on the table
• Ex Groups
• H, Li, Na all form similar oxides
• (H2O, Li2O, Na2O)
• Location gives you A LOT of information

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Periodic Properties

• 2 Main Factors for Periodic Properties
• Number of Levels The more levels, the less
  tightly the electrons are held
• More shielding
• More electron to electron repulsion (PUSH)
• Number of Protons More protons hold electrons
  more tightly. Greater effective nuclear charge
  (Zeff) (PULL)

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Periodic Properties

• Properties we will study
• Size of Atoms
• Size of Ions
• Ionization Energy
• Multiple Ionization Energy
• Electron Affinity

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Size of Atoms

• Atomic Radius
• 1. Measured in
• picometers (1pm 1 X 10-12 m) or Angstroms
  (1 Å 100 pm)
• 2. Average radius 100 pm (1 Å)

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Size of Atoms

• 3. Example Bromine 1.14 Å
• 1.14 Å X 100 pm 114 pm
• 1 Å

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Effective Nuclear Charge

• Zeff Z-S
• Z protons
• S core electron

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• What is the Zeff for chlorine (1s22s22p63s23p5)?
• Zeff Z-S
• Zeff 17- 10 7

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Size of Atoms

• Down a group
• Atoms get larger (more levels)
• Shielding Effect Core electrons shield the pull
  of the nucleus (more electron repulsion) (PUSH
  wins)
• H 1 level Zeff 1
• Li 2 levels Zeff 1
• Na 3 levels Zeff 1

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Size of Atoms
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Size of Atoms

• Across a period atoms get smaller (same level),
  greater Zeff (PULL wins)
• Li F
• Zeff 1 Zeff 7

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Size of Atoms

• Si Cl

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Size of Ions

• A. Positive Ions
• 1. Example
• Mg Mg
• Zeff 2 Zeff 2

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Size of Ions
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Size of Ions

• 2. Positive ions are ALWAYS smaller than the
  neutral atom
• 3. Same protons but less mutual repulsion
  among remaining electrons (PULL wins)

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• Mg Mg Mg2
• Zeff Zeff Zeff

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• Mg Mg Mg2
• Zeff 2 Zeff 2 Zeff 10

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Size of Ions

• B. Negative Ions
• 1. Example
• O O2-
• Zeff 6 Zeff 6

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Size of Ions
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Size of Ions

• 2. Negative ions are ALWAYS larger than the
  neutral atom
• 3. Same protons but more mutual repulsion
  among electrons (PUSH wins)

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Size Review

• Which is larger and why?
• Li or K
• S or S2
• Mg or S
• O or Te

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Size Review

• Kurveball
• K or K

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Ionization Energy

• A.Ionization energy The energy needed to remove
  an electron from an isolated gaseous atom or ion
• Na ? Na e-

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He
Ne
Ar
H
Li
Na
K
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A high energy photon may ionize an atom
(completely remove the electron)
A low energy photon will excite an electron
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Ionization Energy

• B. Ionization is inversely proportional to atomic
  radius
• Examples
• Li (520 kJ/mol) F (1681)
• Na (496 kJ/mol) Cl (1251)

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Ionization Energy

• Which has the higher Ionization Energy and why?
• C or O
• Na or Cl
• C or Sn
• Mg or Ra

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Multiple Ionization Energy

• Multiple Ionizations - Removing more than one
  electron
• 1st Mg ? Mg e- 738 kJ/mol
• 2nd Mg ? Mg2 e- 1450 kJ/mol
• 3rd Mg2 ? Mg3 e- 7732 kJ/mol
• There is a large jump once you reach Noble Gas
  Configuration (Fewer levels, spike in Zeff)

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Multiple Ionization Energy
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Multiple Ionization Energy

• 1st Al ? Al e- 577 kJ/mol
• 2nd Al ? Al 2 e- 1816 kJ/mol
• 3rd Al 2 ? Al 3 e- 2744 kJ/mol
• 4th Al3 ? Al4 e- 11580 kJ/mol

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Multiple Ionization Energy

• Examples
• a. Where will the large jump in I.E. occur for
• Be B P
• b. Element X has a large jump between its 4th
  and 5th I.E. To what group does it belong?

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Electron Affinity

• Energy change that occurs when an electron is
  added to an isolated gaseous atom or ion
• Ease with which an atom gains an electron
• Cl(g) e- ? Cl-(g) DE -349 kJ/mol
• Positive for noble gases (dont want electrons)

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Properties of Metals

• Malleable and ductile
• Good conductors
• Large radius/Low ionization energy
• Form positive ions (2 and 3 for transition
  metals)

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Metal Oxides

• Most metals oxidize easily in the atmosphere
• 2Ni(s) O2(g) ? 2NiO(s)
• Metal oxides are bases
• Metal Oxide Water ? Metal hydroxide (base)
• Na2O(s) H2O(l) ? 2NaOH(aq)
• CaO(s) H2O(l) ? Ca(OH)2(aq)
• Metal Oxide Acid ? Salt Water
• MgO(s) HCl(aq) ? MgCl2(aq) H2O(l)
• NiO(s) H2SO4(aq) ? NiSO4(aq) H2O(l)

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• Predict the products in the following reactions
• Al(s) O2(g) ?
• Zn(s) O2(g) ?
• CaO(s) H2O(l) ?
• Li2O(s) H2O(l) ?

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• Predict the products in the following reactions
• Al2O3(s) HNO3(g) ?
• CuO(s) H2SO4(g) ?

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Properties of Non-Metals

• Dull
• Poor conductors
• Solids, liquids and gases
• Non-metal oxides are acidic

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Non-metal Reactions

• Combination Reactions
• 2Al(s) 3Br2(l) ? 2AlBr3(s)
• Non-Metal Oxide Water ? Acid
• CO2(g) H2O(l) ? H2CO3(aq)
• P4O10(s) 6H2O(l) ? 4H3PO4(aq)
• Non-Metal Oxide Base ? Salt Water
• CO2(g) 2NaOH(aq) ? Na2CO3(aq) H2O(l)
• SO3(s) 2KOH(l) ? K2SO4(aq) H2O(l)

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• Predict the products in the following reactions
• Ba(s) S8(g) ?
• Ga(s) Se(g) ?
• SO2(s) H2O(l) ?
• SeO2(s) 2NaOH(l) ?
• SO3(s) H2O(l) ?
• (acid rain reaction)

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Group Names
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Trends Alkali Metals

• Soft, reactive (M ? M e-)
• Reactions with water
• Na(s) 2H2O(l) ?2NaOH(aq) H2(g)
• Reactions with hydrogen (less electronegative
  than hydrogen)
• 2Na(s) H2(g) ? 2NaH(s) H-, hydride ion
• Reactions of Na and K with oxygen (exceptions)
• 2Na(s) O2(g) ? Na2O2(s) peroxide
• K(s) O2(g) ? KO2(s) superoxide

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Trends Alkaline Earth Metals

• Become more reactive as you go down the table
  (just like alkali metals)
• 99 of calcium in the body is in the skeleton

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Trends Transition and Post-Transition Metals

• Often 2 and 3 ions
• Pt and Au are fairly unreactive

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Trends Hydrogen

• Non-metal
• Forms hydrides (H-) with alkali and alkaline
  earth metals
• 2Na(s) H2(g) ? 2NaH(s)
• Ca(s) H2(g) ? CaH2(s)

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Trends Chalcogens

• Ozone O3 (between 10-50 km in the atmosphere,
  allotrope of oxygen)
• Hydrogen peroxide
• H2O2(aq) ? 2H2O(l) O2(g)
• -good oxidizing agent/disinfectant
• -Can be decomposed by light

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Trends Halogens

• Salt formers
• Reactivity decreases down the table
• Fluorine is most reactive
• Chlorine as a bleaching agent
• Cl2(g) H2O(l) ? HCl HOCl (bleach)
• NaOCl (Clorox)
• Ca(OCl)2 (swimming pool bleach)

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Noble Gases

• Some do react
• XeF4 shown below

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• SO2(s) 2NaOH(l) ?
• Cu(s) O2(g) ?
• Ba(s) H2(g) ?
• SeO3(s) H2O(l) ?
• Al(s) F2(g) ?
• Ca(s) O2(g) ?
• CO2(s) H2O(l) ?
• CaO(s) H2O(l) ?

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• K2O(s) H2O(l) ?
• CO2(s) 2NaOH(l) ?
• Al2O3(s) HCl(g) ?
• Ga(s) Te(g) ?
• SO2(s) H2O(g) ?
• Li(s) H2O(l) ?
• Na(s) O2(g) ?
• Ca(s) S8(g) ?