Catalyst – February 1s22s1, 2011

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 (3rd 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…

http://www.chemicalelements.com/show/electronconfig.html

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 how 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)

Element Atomic Radius (picometer)

Hydrogen 37

Lithium 152

Sodium 186

Potassium 227

Rubidium 248

Cesium 265

1 picometer = 1 x 10-12 m

Elements and their Atomic Radii (2)

Element Atomic Radius (picometer)

Lithium 152

Beryllium 112

Boron 85

Carbon 77

Nitrogen 75

Oxygen 73

Fluorine 72

Neon 71

1 picometer = 1 x 10-12 m

Atomic Size – Graph 1

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6 7

Element

Ato

mic

Ra

diu

s (

pic

om

ete

r)

H Li

Na K Rb Cs

Atomic Size – Graph 2

0

20

40

60

80

100

120

140

160

0 2 4 6 8 10

Element

Ato

mic

Ra

diu

s (

pic

om

ete

r)

Li Be B C N O FNe

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, SP < 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)

Element Electronegativity (Paulings)

Hydrogen 2.20

Lithium 0.98

Sodium 0.93

Potassium 0.82

Rubidium 0.82

Cesium 0.79

Francium 0.70

Elements and their Electronegativity (2)

Element Electronegativity (Paulings)

Lithium 0.98

Beryllium 1.57

Boron 2.04

Carbon 2.55

Nitrogen 3.04

Oxygen 3.44

Fluorine 3.98

Electronegativity Graph 1

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6 7 8

Element

Ele

ctro

neg

ativ

ity

Electronegativity Graph 2

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 2 4 6 8

Element

Ele

ctro

neg

ativ

ity

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, Tc Set 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, Br Set 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, Tc Set 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, Br Set 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