St. George's College
Subject: 8th CHEMISTRY
Class: Initial attempts
Teacher's notes
Objectives
Vocabulary
to classify the elements
Date: June 8th
Link and Learn
Prepared by
2009 1
8th Milton A ‐ Valence Electrons Name
Oral Intervention
Coin
Chocolate
Sergio María Fernanda Alejandra Almendra Anna Paula Sandra E‐C Maia María Belén Alfredo Kinley Arianne Sandra M. Fiorella Rodrigo Giulia Jaime Stefano Bruno
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8th Milton Alpha ‐ Valence Electrons Name
Oral Intervention
Coin
Chocolate
Marcelo Antonella Paulo Alejandro Brenda Diego Gabriel Valeria Cristina Giuliana Joshua María Gracia Gonzalo N. Paolo Gonzalo R. Giorgio Nicolás María Claudia
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Let's remember previous learned concepts...
Wanna Play?
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8th Chemistry ‐ Alpha
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8th Chemistry ‐ A
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Johann Dobereiner • Starting in 1817, this German chemist first made the link between atomic masses and properties. • He grouped elements in sets of three (triads). For example: chlorine, bromine and iodine. • Other chemists did not accept his theory because only a few elements were known, and not all fitted into triads.
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Dobereiner
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John Newlands • In 1864, this British chemist proposed the Law of Octaves (an idea from music), where every element had similar properties to the element eight places before or after it. • Newlands' arrangement of some of the elements is shown below: 1
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3
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H
Li
Be
B
C
N
O
F
Na
Mg
Al
Si
P
S
Cl
K
Ca
Cr
Ti
Mn
Fe
• Newlands' table was not accepted because not all elements fitted the pattern of octaves and the link to music was ridiculed.
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Dmitri Mendeleev • In 1869, Russian scientist Dmitri Mendeleev solved the problem. He also tried putting the element in order of their atomic mass. He made a table of elements. • New rows were started so that elements which were alike could line up together in columns. He wanted a table of regular periodic patterns. • When the pattern began to go wrong, he left gaps in the table, arguing that those gaps were for elements not discovered yet. He even changed the order when similar elements didn't line up. • Because Mendeleev was using atomic masses, there were still discrepancies in the table.
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The Periodic Table.....Animated
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Resources Used Slide (Group)
Resource
Description
Origin
G1 ‐ 2
Image
Beethoven
http://bit.ly/Q7ggk
G1 ‐ 3
Image
Mozart
http://bit.ly/18LkW6
G1 ‐ 5 Image
IS Units and Prefixes http://tinyurl.com/c9d69c Units
http://tinyurl.com/c9yest
G1 ‐ 8 Animation
Timeline
Notebook Gallery
G1 ‐ 10 Images
Dobereiner Triads
http://bit.ly/Cx2rY
G1 ‐ 12 Images
Newlands Octaves
http://bit.ly/11WTZv http://bit.ly/gHzPZ
G1 ‐ 14 Images
Mendeleev
http://bit.ly/Pkbmw http://bit.ly/rSgUf
G1 ‐ 6
Image
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Teacher's Notes This class has been designed to cover the topics of Initial attempts to classify the elements from Monday June 8th till Friday June 12th. For further knowledge about this topic: 1. Conduct a thorough search under the topic: Chemical Elements: Classification on the Web, books and magazines. 2. If findings are not specific, ask your teacher for suggestions.
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Objectives • Understand and evaluate the initial attempts of classification of chemical elements. • Learn and remember the most common atoms, chemical symbols and atomic numbers according to the periodic table.
Note: All, or most, of the objectives will be covered during class time, however the student must be responsible for those objectives not covered or concluded.
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Vocabulary • • • • • •
Element: Atomic Number: Atomic Mass: Dobereiner: Newlands: Mendeleev:
Note: Most of the vocabulary words will be covered during class time, however the student must be responsible for those words not covered or concluded.
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Link and Learn You can visit the following websites to improve your understanding on the present topic: • http://science‐learning2009.wikispaces.com • http://learningandscience.blogspot.com • http://libraryatstgeorge.blogspot.com
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Prepared by
Gerardo LAZARO Science Lead Teacher Email: glazaro@sanjorge.edu.pe Wiki: http://science‐learning.wikispaces.com Blog: http://learningandscience.blogspot.com Twitter: http://twitter.com/glazaro
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