Catalyst – October (2x[2+4]), 2009 Monday Mystery Element  Discovered by boiling urine  There are 2 forms: white and red  The white forms combusts in air Don’t forget to make your Weekly Goal!

Catalyst – October (2x[2+4]), 2009 Monday Mystery Element  Discovered by boiling urine  There are 2 forms: white and red  The white form combusts in air PHOSPHORUS!

Today’s Agenda  Catalyst  More secrets of the PT: Valence Electrons, Atomic Size, and Electronegativity  Group Work Time  Exit Question

Today’s Objectives  SWBAT determine periodic trends for valence electrons, atomic size, and electronegativity.

Valence Electrons Don’t forget!  Valence electrons are the electrons in the outermost energy level.

Example  Electron configuration for silicon (Si):  What is the highest energy level?  So how many valence electrons? 1s 2 2s 2 2p 6 3s 2 3p = 4!

Group Challenge  Each group will write electron configurations for the elements in ONE family. Then, count the number of valence electrons for each configuration.  Group 1: Alkali Metals  Group 2: Alkaline Earth Metals  Group 3: Boron’s Group  Group 4: Carbon’s Group  Group 5: Nitrogen’s Group  Group 6: Halogens  Group 7: Noble Gases  Group 8: Noble Gases

Group Challenge  Each group will write electron configurations for the elements in ONE family. Then, count the number of valence electrons in each configuration.  Group 1: Alkali Metals  Group 2: Boron’s Group  Group 3: Carbon’s Group  Group 4: Nitrogen’s Group  Group 5: Halogens  Group 6: Noble Gases

Valence Electrons

What is Atomic Size?  Atomic size is…  How big an atom is  Also known as atomic radius

Graphing Atomic Size (Radii)  Draw 2 line graphs  X-axis: Element  Y-axis: Atomic Radius (picometers)

Elements and their Atomic Radii (1) ElementAtomic Radius (picometer) Hydrogen37 Lithium152 Sodium186 Potassium227 Rubidium248 Cesium265 1 picometer = 1 x m

Elements and their Atomic Radii (2) ElementAtomic Radius (picometer) Lithium152 Beryllium112 Boron85 Carbon77 Nitrogen75 Oxygen73 Fluorine72 Neon71 1 picometer = 1 x m

Atomic Size – Graph 1 HLi NaKRbCs

Atomic Size – Graph 2 Li BeB CN O F Ne

What trend(s) do you notice?

Atomic size DECREASES as you go across the Periodic Table Atomic size INCREAESES as you go down thePeriodic Table

Atomic Size Key Point #1: Atomic size increases as you go down the periodic table and decreases as you go left to right across the periodic table.

Practice Problems  Rank the following elements in order of increasing atomic size based on location on the periodic table (smallest to biggest) Fr, Sc, P, Pd F, As, Tl, S P, Pd, Sc, Fr Fluorine, Sulfur, Arsenic, Thallium

Practice Time! 1. T or F? Atomic size decreases as you move right across the periodic table. 2. T or F? As you move down the Periodic Table, atoms get smaller. 3. Rank the following sets of elements in order of increasing atomic size (small  big). Set A: Bh, Mn, Re, TcSet B: Sb, I, Ag, Ru Set C: Y, Ti, Sg, Ta 4. Rank the following sets of elements in order of decreasing atomic size (big  small). Set A: Cl, At, I, F, BrSet B: Te, Xe, Sn, In Set C: Rb, K, Sr, Ca

What is electronegativity?  Electronegativity is…  The ability of an atom to attract electrons to itself in a chemical bond  How much an atom wants electrons

Graphing Electronegativity  Draw 2 line graphs  X-axis: Element  Y-axis: Electronegativity (Paulings)

Elements and their Electronegativity (1) ElementElectronegativity (Paulings) Hydrogen2.20 Lithium0.98 Sodium0.93 Potassium0.82 Rubidium0.82 Cesium0.79 Francium0.70

Elements and their Electronegativity (2) ElementElectronegativity (Paulings) Lithium0.98 Beryllium1.57 Boron2.04 Carbon2.55 Nitrogen3.04 Oxygen3.44 Fluorine3.98

Electronegativity Graph 1

Electronegativity Graph 2

What trend(s) do you notice?

Key Point – Atomic Size Key Point #1: Atomic size increases as you go down the periodic table and decreases as you go left to right across the periodic table.

Electronegativity Trends

Electronegativity Key Point #2: Electronegativity decreases as you go down the periodic table and increases as you go left to right across the periodic table.

Practice Problems  Rank the following elements in order of increasing electronegativity based on location on the periodic table (smallest to biggest) Mg, Sr, Be, Ra Cl, Si, Al, S, P Radon, Strontium, Magnesium, Beryllium Aluminum, Silicon, Phosphorus, Sulfur, Chlorine

Practice Time! 1. T or F? Electronegativity decreases as you move left across the periodic table. 2. T or F? As you move down the Periodic Table, atoms get more electronegative. 3. Rank the following sets of elements in order of increasing electronegativity (small  big). Set A: Bh, Mn, Re, TcSet B: Sb, I, Ag, Ru Set C: Y, Ti, Sg, Ta 4. Rank the following sets of elements in order of decreasing electronegativity (big  small). Set A: Cl, At, I, F, BrSet B: Te, Xe, Sn, In Set C: Rb, K, Sr, Ca

How does atomic size related to electronegativity? Key Point #3: Atomic size is indirectly related to electronegativity. ELECTRONEGATIVITY ATOMIC SIZE As electronegativity increases, atomic size decreases!

Why is this relationship true?  Atoms with HIGH ELECTRONEGATIVITIES hold their electrons very close!  Sooooo, the atomic size decreases High or low electronegativity? Large or small atomic size?

Group Work Time! Bohr Models Electron Confuguration Rank by Atomic Size and Electronegativity Similarities Decorate and be creative!

Exit Question 1. Which element has atoms with the smallest size: Cl, Se, P, or F? 2. Which element has the largest electronegativity: Ag, Cu, Hg, or Zn? 3. As electronegativity increases, atomic size….?