Catalyst – September 2(7), 2010

1. What is the atomic number of silicon (Si)?

2. How many protons, neutrons, and electrons does sodium (Na) have?

3. Who discovered the electron?

HW OUT PLEASE!

Today’s Agenda

Catalyst Homework Review Bohr Models! Personal and Group Work Time Exit Question Return and go over Quizzes (10

min) Progress Reports

Today’s Objectives

SWBAT draw Bohr models of the first 20 elements on the periodic table.

SWBAT draw Bohr models for 5 elements in their family.

Front Door

Projector3rd Period

Group 3

Ebony, Waynell,

Quanetta, Warren

Group 5

Alessandro, Bao, Kara

Group 1

Chicobi, Tashelle,

Jamie, Sara

Group 6

Kendell, Jasmine,

Corey, Kiedra

Group 2Melvin, Paula, Amber, Tigler Group 4

Brandon, Ariel, Shawn

Front Door

Projector4th Period

Group 3

Infinity, Jytte, Lyndon, Jeremy

Group 2

Khallid, Shannon, Rodrea, Daniel

Group 1

Jon, Sam, Josh’shawn,

Kourtney

Group 6

Kentrell, Eddie, Artrel,

Darreal

Group 5

Lester, Dwanyetta,

Jaron, Aaron

Group 4

Brittany, Chelsie, Troy,

Nia

Group 9Group 8

Kim, Roniece, Caleb

Group 7

Lizzeh, Rachel

Atomic Number (small whole number)

Navigating the Periodic Table

Element Symbol(letters)

Atomic Mass(big decimal number)

Atomic Number is an Element’s ID Number

Like your social security number or a professional athlete’s jersey number, the atomic number of an element identifies that element

Navigating the Periodic Table What is the atomic

number of…1. Lithium?2. Magnesium?3. Silver?4. Boron?

312

47

5

Find the atomic number of this element

Find the atomic number of this element

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)

Work Time

Draw Bohr Models for the first 20 elements on your notes sheet

We will do a few together first Remember, find the number of protons,

electrons, and neutrons first…then get drawing!

Work for at least 10 minutes on your own…then finish sheet on your own time

Work with your group members to draw Bohr models for 5 of your family’s elements

Exit Question

1. Draw the Bohr model for Lithium (Li).

Homework: Quiz 2.1 Resume,

Trends w/ Bohr Models Worksheet,

Work on Project

Quiz Averages

3rd Period: 71.8%

4th Period: 69.9%

Theory Reading

New advances in radiocarbon dating are threatening to alter old theories about when modern humans migrated to Europe from Africa and how rapidly they advanced. The research casts new light on significant patterns of human migration into Central and Western Europe in the crucial period from 50,000 to 35,000 years ago, scientists say. It suggests that the dispersal of anatomically modern Homo sapiens into Europe was more rapid than previously thought. For years, it had been thought that modern humans from Africa began arriving in Western Europe at least 40,000 years ago, and so could have competed and mingled with the local population for at least 12,000 years. The revised dating of fossils and artifacts leaves much less time for two species to have been in close contact.

Radiocarbon dating, introduced shortly after World War II, has been widely used in measuring time in prehistory. It works by measuring the rate of decay of carbon 14 in once living materials, like plant and animal remains. Recent research at the University of Oxford has led to a more effective filtration process to reduce contamination in test samples; however, contamination can still happen.

In previous estimates, the modern human dispersal through Europe occurred 43,000 to 36,000 years ago. The 7,000-year period implies an overall dispersal rate of about 0.3 kilometers a year, less than two-tenths of a mile. Starting somewhat earlier, the faster dispersal over 5,000 years is now clocked at 0.4 kilometers a year. Scientists cautioned that the revised dating based on new research must be viewed as provisional, concluding that the implications of the new studies "will need to be kept under active and vigilant review."