Catalyst – February 1s 2 2s 1, Define trend. 2. Define radius.

Today’s Agenda  Catalyst  Review Periodic Table Basics Worksheet  Periodic Trends: Notes and Work Time  Exit Question HW: ANSWER CHAPTER 6 ASSESSMENT QUESTIONS 31, 49, 56, 69, 73

Today’s Objectives  SWBAT describe the periodic trends for valence electrons, atomic radius, and electronegativity.

Reward Vote (3 rd Period)  Donuts  Oreos  Chocolate Chip/Sugar Cookies  Granola/Fruit  Other (tell me what you’d like!)

PERIODIC TRENDS!!! VALENCE ELECTRONS (CHECK!) ATOMIC RADIUS ELECTRONEGATIVITY

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

Let’s look at Bohr Models… 

Valence Electrons – Right on your PT

Trend for Valence Electrons  Key Point #1: Number of valence electrons increases from 1-8 as you go right across the periodic table.

What is Atomic Radius?  Key Point #2: Atomic radius is h ow big an atom is and is also known as atomic size.

What is Electronegativity?  Key Point #3: Electronegativity is the ability of an atom to attract electrons to itself in a chemical bond. How much an atom wants electrons

Graphing Atomic Radius (Size)  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?

TRENDS FOR ATOMIC RADIUS  Key Point #4: 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 < Sc < Ps < Fr F < S < As < Tl

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?

Electronegativity Trends

TRENDS FOR ELECTRONEGATIVITY Key Point #5: 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 Ra < Sr < Mg < Be Al < Si < P < S < Cl

So as you go LEFT to RIGHT…  TO SUM IT UP: As you move left to right across the periodic table, positive charge increases so…  ELECTRONEGATIVITY INCREASES  Therefore, ATOMIC RADIUS DECREASES

So as you go from TOP to BOTTOM…  TO SUM IT UP: As you go from top to bottom on the periodic table, energy levels (shells) increase so…  ATOMIC RADIUS INCREASES  Therefore, ELECTRONEGATIVITY DECREASES

How are atomic radius and electronegativity related? Key Point #5: Atomic radius and electronegativity are indirectly/inversely related. ELECTRONEGATIVITY ATOMIC RADIUS

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

Why is this relationship true?  Atoms with LARGE RADII can’t pull on their electrons as much  Soooo, ELECTRONEGATIVITY decreases!

More Practice! 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

More Practice! 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

Exit Question 1. Which element has atoms with the smallest radius: Cl, Se, P, or F? 2. Which element has the largest electronegativity: Ag, Cu, Hg, or Zn? 3. How are atomic radius and electronegativity related? HW: ANSWER CHAPTER 6 ASSESSMENT QUESTIONS 31, 49, 56, 69, 73