Catalyst – February 13, 2012

Monday Mystery Element!

1. Easily magnetized2. Important for human

nutrition by preventing anemia

3. Can become radioactive and emit gamma rays (can treat cancer)

Catalyst – February 13, 2012

Monday Mystery Element!

1. Easily magnetized (like your heart is for Chemistry)

2. Important for human nutrition by preventing anemia

3. Can become radioactive and emit gamma rays (can treat cancer)

COBALT!

Today’s Agenda

Catalyst Review Quiz 2.1 Notes: Bohr Models and Periodic

Trends Work Time Exit Question

HOMEWORK:ATOMIC TRENDS WORKSHEET

Today’s Objectives

SWBAT draw Bohr Models for the first 20 elements like pros!

SWBAT describe the periodic trends for valence electrons, atomic radius, and electronegativity.

Quiz 2.1 Grade Averages

2nd Period: 72.5% (D) 3rd Period: 71.6% (D) 5th Period: 64.9% (F)

FYI: Ms. Stroh added 5 points to the grade you see

on your paper.

Quiz 2.1 Champs

1st Place (102!): Ryan Craigie (3rd)

2nd Place (97): Josh Hayes (3rd), Destiny Rhea (3rd)

3rd Place: Jaymie Mayberry (3rd)

NOTES:BOHR MODELS

Bohr Models of Atoms

Key Point #1: A Bohr model depicts an atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus

16 p+

16 no

Sulfur: 16 protons

16 neutrons

16 electrons

Energy Levels

Key Point #2: Energy levels (or shells) are paths around the nucleus where electrons travel Energy levels are also known as orbits

Energy increases as you move further from the nucleus

Valence Electrons

Key Point #3: Valence electrons (ve-) are electrons in the outermost energy level They are the furthest from the nucleus

An atom could have 1 ve-, 2 ve-, 3 ve-, etc.

Steps to Making a Bohr Model

1. Determine the number protons, neutrons, and electrons in the atom

2. Draw the nucleus (circle) with # p+ and # no

inside3. Draw the first energy level (circle around

nucleus) and draw up to 2 dots (electrons)4. If needed, draw second energy level (second

circle) and draw up to 8 dots (electrons)5. If needed, draw third energy level (third

circle) and draw up to 8 dots (electrons)6. If needed, draw fourth energy level (fourth

circle) and draw up to 18 dots (electrons)

CHECK OVER YOUR BOHR MODELS

DO YOU HAVE ANYQUESTIONS???

NOTES SECTION:PERIODIC TRENDS!!!VALENCE ELECTRONS

ATOMIC RADIUSELECTRONEGATIVITY

Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved..

Although the weather changes from day to day, the weather you experience is related to your location on the globe.

CHEMISTRY & YOUCHEMISTRY & YOU

How are trends in the weather similar to trends in the properties of elements?

Periodic Trends

Key Point #4: There are trends/patterns on the periodic table that help us both compare and contrast elements.

Note-Taking Strategy

Make a T-chart in your notes – like this…. Vocab Word Periodic Trend

Vocab Words (Left)

1. Valence electrons: electrons in the outermost (or outside/biggest) energy level

2. Atomic radius: how big an atom is, also known as atomic size

3. Electronegativity: the ability of an atom to attract electrons to itself in a chemical bond; how much an atom wants electrons

Electronegativity Values for Selected Elements in Paulings

H 2.1

Li 1.0

Be1.5

B2.0

C2.5

N3.0

O3.5

F4.0

Na 0.9

Mg1.2

Al1.5

Si1.8

P2.1

S2.5

Cl3.0

K 0.8

Ca1.0

Ga1.6

Ge1.8

As2.0

Se2.4

Br2.8

Rb 0.8

Sr1.0

In1.7

Sn1.8

Sb1.9

Te2.1

I2.5

Cs 0.7

Ba0.9

Tl1.8

Pb1.9

Bi1.9

VALENCE ELECTRONS TREND

Let’s look at Bohr Models…

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

Valence Electrons Write on your PT

TREND: Valence Electrons# of valence electrons increases from 1-8 as you go left to right

Using Graphs toUnderstand

the Relationship Between

Atomic Radius andElectronegativity

GROUP 1H + Alkali

Metals

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)

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6 7 8

Element

Ele

ctro

neg

ativ

ity

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) PERIOD 1Li - Ne

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

ATOMIC RADIUSTREND

Rank Small to Large: Cs, Ga, P, Rn

ELECTRONEGATIVITY

TREND

Rank Small to Large: Mg, Sr, Be, Ra

Why is this relationship true?

vs.

LARGE EN=

SMALL AR

LARGE AR=

SMALL EN

Work Time

Work on worksheet from Ms. Stroh

Exit Question

1. Draw the Bohr model for Carbon (C).

2. Which element has the largest electronegativity: Ag, Cu, Hg, or Zn?

HOMEWORK:ATOMIC TRENDS WORKSHEET