8th Chemistry - Initial attempts to classify the elements

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

2

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

3

Let's remember previous learned concepts...

Wanna Play?

4

5

8th Chemistry ‐ Alpha

6

8th Chemistry ‐ A

| 7

8

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.

9

Dobereiner

10

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

2

3

4

5

6

7

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.

11

12

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.

13

14

15

The Periodic Table.....Animated

16

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

17

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.

BACK 18

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.

BACK 19

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.

BACK 20

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

BACK 21

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

BACK 22