8th Chemistry - Particles, Atoms and Numbers

St. George's College

8th CHEMISTRY Class:

Particles, Atoms and Numbers March 23rd

2009

Teacher's notes

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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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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Can we split the atomic particles?

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FACT 1

FACT 2

FACT 3

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INSIDE THE ATOM We already know that the components of atoms are: Neutrons

Protons

Electrons

Particle Symbol Charge

Mass (Kg)

Size (m)

Neutron

n0

0

1.67495 x 10‐27 10‐15

Proton

p+

+1

1.67265 x 10‐27 10‐15

Electron

e‐

‐1

9.1095 x 10‐31 10‐18

0

Variable

ATOM

10‐10

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ASSIGNMENT

E‐Portfolio Investigate: 1. What are the forces that hold the nuclear components of the atoms?

2. What are the subatomic particles? Describe their type and function.

Publish it in your Wiki (E‐Portfolio).

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QUANTUM MECHANICS

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ENERGY LEVELS • Electrons move around the nucleus (negative charge around positive charge).

• Even though it looks as if this movement is disorganized, in fact there is a strict organization of the electrons.

• Electrons move around the nucleus packed in Energy Levels.

• Energy levels are the "layers" around the nucleus where electrons are found in motion.

• These energy levels are called Electron shells.

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ELECTRON SHELLS

proton

e‐

neutron

e‐ e‐

e

e‐

‐

e‐

electron

e‐ e‐ e‐

How many electron shells are there in the graphic?

How many electrons are there in the graphic?

What is the atomic number of the atom in the graphic?

What element is represented in the graphic?

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Rules to fill up the Electron Shells 1. The first electron shell, the closest to the nucleus can hold up to 2 electrons.

2. The other electron shells can hold many more electrons.

3. The last electron shell can only hold up to 8 electrons, this is called the Octet Rule.

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Filling up the Electron Shells

proton

Represent the following atoms:

neutron

An Atom with 7 protons

e‐

electron

An Atom with 23 electrons

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The Current Atomic Model

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QUANTUM MECHANICS UNCERTAINTY PRINCIPLE ‐ Werner Heisenberg It is not possible to simultaneously determine the speed and position of the electron accurately.

ATOMIC ORBITAL: region in space where it is more probable to find the electron.

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QUANTUM NUMBERS: are mathematical expressions used to describe the energies of atoms, angular moment, electron spin, etc. It is used to determine the distribution of atoms in the atomic orbitals.

Quantum Number

Function

n principal quantum number Energy Level Determines the energy level where the e‐ is located. The higher n value, the farthest the e‐ from the nucleus.

Values 1,2,3,4,5,6,7

Shape of the atomic orbital Energy Sublevel

0 < l < n‐1

m magnetic quantum number Space representation of the It represents the space orientation of atomic orbitals the orbitals in the energy sublevels.

l < m < l‐1

s spin quantum number It describes the spin orientation of the e‐.

‐½, +½

l secondary quantum number (azimuthal or orbital) Determines the energy associated with the e‐ movement around the nucleus; it indicates the energy sublevel.

Shows the electron spin

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Quantum Numbers n value

1

2

3

4

l value

1

0, 1

0, 1, 2

0, 1, 2, 3

Sublevel value

1

2

3

4

s

p

d

f

l

1

2

3

4

0

3s

0

1

2

1

3p

‐1, 0, 1

3

6

2

3d

‐2, ‐1, 0, 1, 2

5

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n value

l value

Sublevel

Maximum number of e‐

1

0

s

2(1)2 = 2

2

1

p

2(2)2 = 8

3

2

d

2(3)2 = 18

4

3

f

2(4)2 = 32

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Shapes of Atomic Orbitals l secondary quantum number (azimuthal or orbital)

Orbital s: Sphere symmetry.

The size of orbital "s" increases when the principal quantic number increases too.

Orbital p: lobe‐shaped orbitals.

There are 3 types of "p" orbitals, differing by their orientation.

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Orbital d: third sublevel of energy.

There are 5 types of "d" orbitals, with different space orientations.

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Orbital f: complex orientations.

There are 7 types of "f" orbitals, with different space orientations.

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Let's check an example on how to fill the electron shells.

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ATOMIC PROPERTIES

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ATOMIC NUMBER • Each element has an Atomic Number, and is determined by the number of protons.

• All the atoms of a particular element have the same number of protons.

Atomic Number = Number of Protons

MASS NUMBER • The mass of each element is determined by the number of protons and neutrons.

• The mass of electrons is so minute that it is not considered in the calculations of the atomic mass.

Atomic Mass = Number of Protons + Number of Neutrons 23

ISOTOPES • Some elements are made up of atoms with different masses.

• For atomic masses, the number of protons always remains the same.

• Isotopes are elements with a different number of neutrons. e‐

e‐

e

e‐

‐

e‐

e‐

e

e‐

‐

e‐

e‐

e‐

e‐

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The Nuclei of the three isotopes of Hydrogen

Protium

Tritium

+

+

1 proton

1 proton 1 neutron

Deuterium

+ 1 proton 2 neutrons

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Resources Used Description

Slide Resource (Group)

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 ‐ 6 Images

Neutron Protons Electrons Atom Size scale

http://bit.ly/8gtbk http://bit.ly/vV9H0 http://bit.ly/uJsB4 http://bit.ly/11x5DK http://bit.ly/4EUdnd

G1 ‐ 8 Image

Orbitals

http://bit.ly/ieXj

G1 ‐ 11 Image

Electron shells

http://bit.ly/3Rksdj

G1 ‐ 13 Image

Animation

Notebook Gallery

G1 ‐ 14 Image

Atomic Orbitals

http://bit.ly/Laor

G1 ‐ 16 Images

Orbital s Orbitals p

http://bit.ly/3frUSZ http://bit.ly/17brAa

G1 ‐ 17 Image

Orbitals d

http://bit.ly/TUPz

G1 ‐ 18 Image

Orbital f

http://bit.ly/GW1Zq

G1 ‐ 19 Image

Hybrid orbitals

http://bit.ly/ssfpL

G1 ‐ 20 Image

Hybrid orbitals

http://bit.ly/ssfpL

G1 ‐ 21 Image

Electron Shells

http://bit.ly/bJUj

G1 ‐ 22 Image

Atoms

http://bit.ly/BqTh

G1 ‐ 25 Images

Helium Isotopes Carbon 14 Isotopes

http://bit.ly/Hhz7Z http://bit.ly/10rlfM

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Teacher's Notes This class has been designed to cover the topics of Atomic Particles 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: Atomic Particles on the Web, books and magazines.

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

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Objectives • Describe properties and elements that compose the atom.

• Identify and describe the forces that hold the atomic particles together.

• Understand and calculate the atomic number and atomic mass of elements.

• Familiarize with the chemical elements and its nomenclature.

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://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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