View by Category

Loading...

PPT – Atomic Structure PowerPoint presentation | free to download

The Adobe Flash plugin is needed to view this content

About This Presentation

Write a Comment

User Comments (0)

Transcript and Presenter's Notes

Atomic Structure

- The theories of atomic and molecular structure

depend on quantum mechanics to describe atoms and

molecules in mathematical terms.

Quantum Mechanics

- The Bohr Atom (quantization of energy levels)
- The equation only works well for hydrogen-like

atoms. - Wave nature of the electron
- E h hc/, h/mv (de Broglie wavelength)
- Not possible to describe the motion of an

electron precisely. - Heisenbergs Uncertainty Principle
- xpx h/4
- Electrons in an atom have to be described in

regions of space with certain probabilities.

The Schröndinger Equation

- Describes the wave properties of an electron in

terms of its position, mass, total energy, and

potential energy. - Based on the wavefunction, , which describes an

electron wave in space (i.e. orbital). - The equation used for finding the wavefunction of

a particle. - Used to find the wavefunctions representing the

hydrogenic atomic orbitals.

The Schröndinger Equation (SE)

- H E
- H is the Hamiltonian operator which when

operating on a wavefunction returns the original

wavefunction multiplied by a constant, E. - Carried out on a wavefunction describing an

atomic orbital would return the energy of that

orbital. - There are infinite solutions to the SE each

solution matching an atomic orbital. - Each solution (or ) is represented with a set of

unique quantum numbers. - Different orbitals have different and,

therefore, different energies.

The Schröndinger Equation (SE)

- Properties of the wavefunction, .
- Probability of finding an electron at a given

point in space is proportional to 2. - The must be single-valued.
- The and its 1st derivative must be continuous.
- The must approach zero as r approaches

infinity. - The probability of finding the electron somewhere

in space must equal 1. - All orbitals must be orthogonal.

Quantum Numbers and Atomic Wavefunctions

- Implicit in the solutions for the resulting

orbital equations (wavefunctions) are three

quantum numbers (n, l, and ml). A fourth quantum

number, ms accounts for the magnetic moment of

the electron. - Examine Table 2-2 and discuss.
- n the primary indicator of energy of the atomic

orbital. - l determines angular momentum or shape of the

orbital. - ml determines the orientation of the angular

momentum vector in a magnetic field or the

position of the orbital in space. - ms determines the orientation of the electron

magnetic moment in a magnetic field. - Only three a required to describe the atomic

orbital.

Hydrogen Atom Wavefunctions

- These are generally expressed in spherical polar

coordinates. - (x,y,z)(r,,)
- r distance from the nucleus
- (0)
- angle from the z-axis
- (0)
- angle from the x-axis
- (02)

Hydrogen Atom Wavefunctions

- In spherical coordinates, the three sides of a

small volume element are rd, rsind, and dr. - r2sindddr (important for integration, Fig.

2-5). - A thin shell between r and rdr is 4r2dr.
- Describes the electron density as a function of

distance.

Hydrogen Atom Wavefunctions

- The wavefunction is commonly divided into the

angular function and the radial function. - (r,,)R(r)()()R(r)Y(,)
- Tables 2-3 and 2-4, respectively.
- Angular function, Y(,)
- Determines how the probability changes from point

to point at a given distance. - Produces the shapes of the orbitals and

orientation in space. - Determined by l and ml quantum numbers.
- Examine Table 2-3 and Figure 2-6 and discuss.

Hydrogen Atom Wavefunction

- Radial function, R(r)
- Determined by quantum numbers, n and l
- Illustrates how the function changes with r
- The radial probability function is 4r2R2
- Describes the probability of finding the electron

at a distance r (over all angles). Examine Fig.

2-7. - The distance that either function approaches zero

increases with n and l. - Why do the radial functions and radial

probability functions differ - Appearance of complex numbers in the

wavefunction. - Properties of these type of equations allows us

to produce real functions out of complex function

(example).

Hydrogen Atom Wavefunction

- A nodal surface is a surface with zero electron

density. and 2 will equal zero. The electron

is not allowed on this surface. The radial

portion or the angular portion of the

wavefunction must equal zero. - Radial nodes, R(r) 0
- Spherical nodal surfaces where the electron

density is zero at a given value of r. - 4r2R2 0 (examine radial probability functions)
- The number of radial nodes n-l-1
- Angular nodes, Y(,) 0
- These are planar or conical surfaces.
- Examine the appearance of the orbitals.
- The number of angular nodes l.

Aufbau Principle (many electron)

- Electrons are placed in orbitals to give the

lowest total energy of the atom. - Lowest values of n and l are filled first.
- Pauli exclusion principle
- Hunds rule of maximum multiplicity
- Coulombic energy of repulsion, c, and exchange

energy, e. - Klechkowkowskys nl rule

Shielding and Other Factors

- Each electron acts as a shield for electrons

farther out from the nucleus. - Degree of shielding depends on n and l.
- Slater rules for determining the shielding

constant (ZZ-S). - Higher n shields lower n significantly.
- Within the same n, lower l values can shield

higher l values significantly.

Shielding and Other Factors

- The electron configurations for Cr and Cu.
- Examine Figure 2-12. In this diagram, the 3d

drops faster in energy than the 4s. - Formation of a positive ion reduces the overall

electron repulsion and lowers the energy of d

orbitals more than that of the s orbitals

according to this figures. - For an better description of why this occurs

consult the reference listed below. - L.G. Vanquickenborne, J. Chem. Educ. 1994, 71, 469

Ionization Energy and Radii

- Ionization energy energy required to remove an

electron from a gaseous atom or ion. - Trends with ionization energy (Figure 2-13).
- Draw a plot of Z/r versus ionization energy.
- Covalent and ionic radii
- As nuclear charge increases, the electrons are

pulled toward the center. More electrons,

however, increase the mutual repulsion. - Size of cations/anions in reference to the

neutral atom. - Other factors can influence size as well.

About PowerShow.com

PowerShow.com is a leading presentation/slideshow sharing website. Whether your application is business, how-to, education, medicine, school, church, sales, marketing, online training or just for fun, PowerShow.com is a great resource. And, best of all, most of its cool features are free and easy to use.

You can use PowerShow.com to find and download example online PowerPoint ppt presentations on just about any topic you can imagine so you can learn how to improve your own slides and presentations for free. Or use it to find and download high-quality how-to PowerPoint ppt presentations with illustrated or animated slides that will teach you how to do something new, also for free. Or use it to upload your own PowerPoint slides so you can share them with your teachers, class, students, bosses, employees, customers, potential investors or the world. Or use it to create really cool photo slideshows - with 2D and 3D transitions, animation, and your choice of music - that you can share with your Facebook friends or Google+ circles. That's all free as well!

For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!

You can use PowerShow.com to find and download example online PowerPoint ppt presentations on just about any topic you can imagine so you can learn how to improve your own slides and presentations for free. Or use it to find and download high-quality how-to PowerPoint ppt presentations with illustrated or animated slides that will teach you how to do something new, also for free. Or use it to upload your own PowerPoint slides so you can share them with your teachers, class, students, bosses, employees, customers, potential investors or the world. Or use it to create really cool photo slideshows - with 2D and 3D transitions, animation, and your choice of music - that you can share with your Facebook friends or Google+ circles. That's all free as well!

For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!

presentations for free. Or use it to find and download high-quality how-to PowerPoint ppt presentations with illustrated or animated slides that will teach you how to do something new, also for free. Or use it to upload your own PowerPoint slides so you can share them with your teachers, class, students, bosses, employees, customers, potential investors or the world. Or use it to create really cool photo slideshows - with 2D and 3D transitions, animation, and your choice of music - that you can share with your Facebook friends or Google+ circles. That's all free as well!

For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!

For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!

Recommended

«

/ »

«

/ »

Promoted Presentations

Related Presentations

CrystalGraphics Sales Tel: (800) 394-0700 x 1 or Send an email

Home About Us Terms and Conditions Privacy Policy Contact Us Send Us Feedback

Copyright 2014 CrystalGraphics, Inc. — All rights Reserved. PowerShow.com is a trademark of CrystalGraphics, Inc.

Copyright 2014 CrystalGraphics, Inc. — All rights Reserved. PowerShow.com is a trademark of CrystalGraphics, Inc.

The PowerPoint PPT presentation: "Atomic Structure" is the property of its rightful owner.

Do you have PowerPoint slides to share? If so, share your PPT presentation slides online with PowerShow.com. It's FREE!

Committed to assisting Byui University and other schools with their online training by sharing educational presentations for free