Catalyst – February 8*3-2, 2.010* 103

Monday Mystery Element

Discovered by boiling urine

There are 2 forms: white and red

The white forms combusts in airDon’t forget to

make your Weekly Goal!

Catalyst – February 8*3-2, 2.010* 103

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.

Why do scientists use graphs?To organize, compare, and display experimental data

To make calculations and predictions

How to Graph

1. Label axes (x = ______, y = _______)

2. Title graph (y-axis vs. x-axis)3. Determine scales4. Plot each point5. Draw trend line (line of best fit)

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?

1s22s22p63s23p2

2 + 2 = 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)

Element Atomic Radius

(picometer)

Hydrogen 37

Lithium 152

Sodium 186

Potassium

227

Rubidium 248

Cesium 265

1 picometer = 1 x 10-12 m Element Atomic

Radius (picomet

er)

Lithium 152

Beryllium

112

Boron 85

Carbon 77

Nitrogen 75

Oxygen 73

Fluorine 72

Neon 71

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?

Atomic size DECREASES as you go across the Periodic TableA

tom

ic size IN

CR

EA

ES

ES

as y

ou

go

dow

n th

e P

erio

dic T

ab

le

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, 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

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)Element Electrone

gativity (Paulings)

Hydrogen 2.20

Lithium 0.98

Sodium 0.93

Potassium

0.82

Rubidium 0.82

Cesium 0.79

Francium 0.70

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

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

Electronegativity Trends

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, BerylliumAluminum, 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, 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

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 decreasesHigh or low electronegativity?

Large or small atomic size?

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….?