Periodic Trends

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Periodic Trends
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State Standard

• SC4. Students will use the organization of the
  Periodic Table to predict properties of elements.
• a. Use the Periodic Table to predict periodic
  trends including atomic radii, ionic radii,
• ionization energy, and electronegativity of
  various elements.
• b. Compare and contrast trends in the chemical
  and physical properties of elements and
• their placement on the Periodic Table.

3
Sponge

• Draw a blank periodic table and label the
  following
• Group numbers
• Alkali metals
• Alkaline earth metals
• Halogens
• Transition metals
• Inner transition metals

• Nonmetals
• Metals
• Rare earth metals
• 8 main groups
• Valence electrons of 8 main groups
• Get graphs out and ready to use

4
Sponge

• Arrange the following elements by increasing
  atomic radius
• A) Br, Sc, Fe, K, Ge
• B) Re, Pt, La, Pb, Cs
• C) Mg, Si, Na, P, S
• D) Pb, Si, Sn, C
• E) Ba, Ca, Sr, Be

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Sponge

• Arrange the following by increasing size
• F, N, Si, P, Zn, Ga, Tc, Zr, Fr, Ba, W
• Which one of the pairs is bigger?
• K or K Cl or Cl- Mg or Mg2
• Zn or Co Ca2 or Ba2 Sb3- or Te2-
• Which one of the pairs has higher 2nd ionization
  energy Rb or Sr Cl or Na
• Which has higher electronegativity?
• Ga or Sb Ag or Rh Ca or Be
• Cl or F As or Tl O or Cl
• Pick a metal and explain how it forms ions.
• Pick a nonmetal and explain how it forms ions.
• What major concept predetermines ion formation of
  elements?

6
Sponge

• List the elements with electron configurations
  ending in s2p2.
• Which has a higher 1st IE and why?
• Li, B, Be
• Which one is larger Mg or Mg2
• Pb2 or Pb4 Sc or La I or I-
• Which has a higher electronegativity?
• Sn or Pb Fe or Co Fr or Al

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Section 14.2

• Periodic means regularly repeating patterns
• We see periodic trends in physical state,
  electron configuration, etc.
• We need to understand the periodic trends of 4
  properties atomic radius, 1st ionization
  energy, ionic size, and electronegativity.

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Group vs period trends

• Remember
• groups are vertical columns
• periods are horizontal rows
• We see regular repeating patterns or periodic
  trends for both groups and periods.

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Read section 14.2 to understand these trends.

• Atomic Radiusthe most important to understand
• Period Trend As move to right, z (p) increases
  by one for each element increasing nuclear charge
  by one each time this pulls in the lower
  electron sublevels (1s, 2s, 2p, etc) thus making
  atom smaller and decreasing radius as move left
  ? right
• Group trend remember the onionas go down,
  adding energy levels (electron layers) so atom is
  getting bigger.

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Read section 14.2 to understand these trends.

• 1st ionization energy the amount of energy
  required to remove a single electron from an atom
  of an element.
• Tied to atomic radius
• Principle As electron gets closer to nucleus,
  harder to remove from atom (positive attracts
  negative) therefore requires more energy to take
  electron away thus higher 1st IE.
• Period Trend AR decreases l?r so 1st IE
  increases l?r
• Group Trend AR increases as go down so 1st IE
  decreases as go down.
• Multiple ionization energies role of noble gas
  configuration (NGC)

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Read section 14.2 to understand these trends.

• Ionic Size 2 groupscations and anions
• Must understand fundamental difference in
  formation of anion vs formation of cation.
• Anions formed by adding electrons to atom thus
  producing negatively charged ions.
• Cations formed by removing electrons from atoms
  thus producing positively charged ions.
• Proton electron ratio for both groups? more
  protons more pull thus electrons pulled closer
  and radius decreases.
• Size of neutral vs. size of anion (Ca vs Ca2, O
  vs O2-)

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Read section 14.2 to understand these trends.

• Electronegativity the tendency of an atom of an
  element to attract electrons to itself in a
  chemical bond.
• Fluorine is boss! Closer are to F on PT, more
  electronegative element is.
• Which element is more electronegative A or B?
• Which element has more electron density in the
  bond between A and B? (substitute in real
  elements)
• Which element has a higher/lower EN A or B?
• EN is a tug-of-war for the bonding electrons.

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Study Guide

• Atomic Models
• Plum Pudding Model (Thomson)
• Solar System Model
• Rutherford nucleus
• Bohr electron movt
• Quantum Mechanical Model electron waves
• Heisenburg, Schrodinger, DeBroglie

• Wave Particle Duality of Nature
• E, ?, v problems
• Electron configuration
• Periodic Trends
• AR, 1st IE, EN, IR
• Families on PT
• Halogens, alkali metals, alkaline earth metals,
  noble gases, lanthanides, actinides, s,p,d,f
  block elements,

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Web Sites

• Good web site for multiple choice questions
• http//www.chem.purdue.edu/gchelp/115exams/pprop2.
  html
• Other sites
• http//science.howstuffworks.com/atom3.htm
• http//chemistry.about.com/library/weekly/aa071802
  a.htm
• http//www.lenntech.com/chemical-properties.htm