8th Chemistry - Atomic theories

St. George's College

8th CHEMISTRY

Class:

Teacher's notes

Atomic Theories

March 18th

2009

Objectives

Vocabulary

Link and Learn

Prepared by

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8th Milton ‐ Atomic Theories Name

Oral Intervention

Coin

Chocolate

Marcelo Antonella Paulo Sergio María Fernanda Alejandro Alejandra Brenda Almendra Diego Anna Paula Gabriel Sandra E‐C Maia Valeria María Belén Cristina Alfredo Giuliana Joshua Kinley Arianne María Gracia Sandra M. Fiorella Gonzalo N. Rodrigo Giulia Paolo Gonzalo R. Giorgio Jaime Stefano Bruno Nicolás María Claudia

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MATTER Identify matter in these pictures:

MATTER

NON‐MATTER 3

MATTER: Atom ‐ Dalton Democritus (2400 yrs ago): The philosopher coined the term ATOM to what he believed matter was formed with.

John Dalton (1808): He had no knowledge about protons, electrons, neutrons, but he realized that differences in substances' atoms made their properties different. He proposed his atomic theory under these terms: • All matter is made up of tiny particles called Atoms.

• All atoms of a given element are alike, but are different from the atoms of any different atom.

• Compound are formed when atoms of different elements combine in fixed proportions.

• A chemical reaction involves rearrangement of atoms, not a change in the atoms themselves.

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These wooden balls were used to represent the first atomic model by John Dalton.

Science Museum, England.

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J. J. Thomson • While investigating electricity, he identified an electrically‐ charged particle that he called an electron.

• A tiny particle, much smaller than the atom, and it had a negative electric charge.

• But if atoms are not charged, how come there is a subatomic particle with a negative charge?

• He answered saying that electrons were embedded in a sphere of positive charges like "raisins in a plum pudding".

• The pudding would represent the positive charges, and the raisins the electrons, making the atom electrically neutral.

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Ernest Rutherford • He tested the plum‐pudding model by shooting positively‐charged particles at a gold foil as bullets.

• He observed that most of them passed through, but a few bounced back.

• He concluded that the plum‐pudding model was wrong, suggesting in 1911 that the atom was mostly empty space, hence the particles passing through.

• Those that bounced back were repelled by a strong positive charge concentrated in a small part of the atom.

• Rutherford suggested that electrons should revolve around a positively‐charged nucleus.

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Niels Bohr • He suggested in 1913 that electrons orbit at different distances from the nucleus, when the electron changes orbit it gives off energy.

• Today, electrons are shown in a "cloud" around the nucleus, called probabilistic region.

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Label the diagram of the atom Click here for the answer

{

Protons

Electrons

Nucleus

Neutrons 13

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Can we split the atomic particles?

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FACT 1

FACT 2

FACT 3

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Reminders • An Atom is the smallest unit of an element that still can be identified as that element.

• Scientists worked over centuries gathering indirect evidence and used it to infer things about the atom.

• Experiments suggest that a single atom is made up of even smaller pieces, or subatomic particles.

• A proton is a subatomic particle that has a positive electric charge. The nucleus, or center, of every atom contains at least one proton.

• A neutron is a subatomic particle that has about the same mass as a proton but no electric charge. In most atoms, the nucleus contains one or more neutrons.

• An electron is a subatomic particle that has a negative charge. It's much smaller and has much less mass than a proton or a neutron. Electrons aren't found in the nucleus, they orbit the nucleus at great speeds.

• Because an atom has equal numbers of protons and electrons, it has no overall charge.

• If all atoms contain the same subatomic particles , what makes elements different from one another?

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ASSIGNMENT

E‐Portfolio • Use your wiki to prepare a publication about the smallest components of atomic particles known until now.

• This publication must contain 100 words as a minimum, and 150 words maximum.

• You can use other resources to complement your publication, such as: audio, video, animations, etc.

• Just remember: CITE your SOURCES of INFORMATION, and USE YOUR OWN WORDS. Click below for the easy way

Click below for the right way

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Teacher's Notes This class has been designed to cover the topics of Particulate Nature of Matter for the week of Monday March 16th till Friday March 18th.

For further knowledge about this topic: 1. Conduct a thorough search under the topic: Particulate Nature of Matter on the Web, books and magazines.

2. If findings are not specific, ask your teacher for suggestions.

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Objectives • Describe the atomic theories and the experiments that lead to them.

• Identify and describe the components of the current atomic model.

• Explain the particulate nature of matter.

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 • Atom: the smallest unit of an element that still has the properties of that element.

• Proton: a subatomic particle that has positive electric charge.

• Nucleus: the control center of a cell that directs the cell's activities. The center of an atom, usually made of protons and neutrons.

• Neutron: a subatomic particle that has the same mass as a proton but no electric charge.

• Electron: a subatomic particle that orbits an atom's nucleus, has a negative electric charge, and has very little mass.

• Atomic Number: the number of protons in an atom.

• Element: a substance made up of only one kind of element.

• Metal: a substance that conducts heat and electricity well and is malleable.

• Nonmetal: a substance that does not conduct electricity and is not malleable.

• Proton: a subatomic particle that has a positive electric charge.

• Periodic Table: a table that shows the elements arranged by their atomic numbers.

• Compound: a substance made up of atoms of two or more elements that are chemically combined.

• Melting Point: the temperature at which a substance changes from a solid to a liquid.

• Boiling Point: the temperature at which a substance changes from a liquid to a gas.

• Plasma: a state of matter made up of charged atoms, uncharged atoms, and free electrons.

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://bit.ly/PvvMp http://bit.ly/xxsu http://science‐learning2009.wikispaces.com http://learningandscience.blogspot.com www.sanjorge.edu.pe http://libraryatstgeorges.blogspot.com

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Prepared by

Gerardo LAZARO Science Lead Teacher Email: glazaro@sanjorge.edu.pe Wiki: http://science‐learning2009.wikispaces.com Blog: http://learningandscience.blogspot.com Twitter: http://twitter.com/glazaro

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The structure of an atom

Nucleus

Electrons

{

Neutrons

Protons Click here to go back

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Resources Used Slide (Group)

Resource

Description

Origin

G1 ‐ 2 Image

John Milton

http://bit.ly/QAYb

G1 ‐ 3 Images

Cow Cloud/Thunder Sodium atom Matter CERN Black hole

Notebook Gallery Notebook Gallery http://bit.ly/jD5z http://bit.ly/gFgAT http://bit.ly/18DtJu

G1 ‐ 5 Images

Wooden Balls Elements

http://bit.ly/JCInm http://bit.ly/PvvMp

G1 ‐ 7 Images

JJ Thomson Cathode Ray Tube Raisins in a Pudding

http://bit.ly/Qpn0G http://bit.ly/aTsuR http://bit.ly/yuNB

G1 ‐ 9 Animation Rutherford's experiment 1 http://bit.ly/11YT09 G1 ‐ 10 Animation Rutherford's experiment 2 http://bit.ly/w4zSg G1 ‐ 11 Animation Bohr's Model

http://bit.ly/13Q7PT

G1 ‐ 12 Animation Plasma

Unknown

G1 ‐ 13,14

http://bit.ly/18R0M

Activities Chemistry

G1 ‐ 15 Animation Atom of Helium

http://bit.ly/JtON

G1 ‐ 16 Image

Atomic particles

Unknown

G1 ‐ 17 Images

Fact 1 Fact 2 Fact 3

http://bit.ly/fW7vM http://bit.ly/RELH http://bit.ly/nMGsZ

G1 ‐ 19 Images

E‐Portfolio Puzzle pieces Copy and Paste Idea

http://bit.ly/W7ccA http://bit.ly/Dbbtf http://bit.ly/2ZxTj Notebook Gallery

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