Chapter 5: Electrons in Atoms

5.2 Electron Arrangement in Atoms When an electron goes to a higher orbit, its energy. When an electron goes to a lower orbit, its energy, and it gives off. Energy Ladder for H 5 E = 2.09 x J 4 E = 2.06 x J 3 E = 1.9 x J 2 E = 1.6 x J 1 E = 0 Joules If an electron goes from orbit 1 to orbit 3, how must its energy change? From orbit 3 to 2? From orbit 2 to 1?

Say goodbye to Bohr’s Model Types of orbitals: 1)Spherical Orbital 2) Pear shaped orbital 3) Complex shaped Problems with the Orbit Model 1. Bohr’s model only predicted the line spectrum for one atom,. 2. Every orbit is unstable. The orbiting particle always “falls” into the center of the orbit. A new model was needed… - electrons do not orbit the nucleus - electrons have properties of both and. Modern Model, Quantum Model Electrons are in orbitals, 3 dimensional regions around the nucleus that indicates the ____ location of an electron.

Electrons “live in” orbitals. An orbital is like a room. Shell: The main energy level occupied by the electron. (Principal Quantum Number, n) Subshell: Different shapes of the main energy level. (Angular Momentum Quantum Number, l) When electrons are put in the orbitals, - the electrons fill low energy “rooms” first, higher energy rooms next. (Aufbau principle) - each “room” can only hold 2 electrons The Electron Hotel Third Floor Second Floor First Floor Orbital Energy Diagram- See pg 133 Fig 5-7 Electron Configuration (Spectroscopic Notation) H 1s 1 He 1s 2 O 1s 2 2s 2 2p 4

Electron Arrangements Using the orbital filling diagram on page 133 of your book, write the electron configurations for: F (9 e-) = Ni(28 e-) = Mg(12 e-) = Orbital (Electron) Energy Diagram 46 4s 3d 3s 3p E 2s 2p Phosphorous ( e -) 1s Electron Configuration P (15 e -) = Valence electrons: Noble Gas Notation: 1s 2 2s 2 2p 5 1s 2 2s 2 2p 6 3s 2 3p 6 3d 8 4s 2 1s 2 2s 2 2p 6 3s 2 1s 2 2s 2 2p 6 3s 2 3p 3 3s 2 3p 3 [Ne]3s 2 3p 3

Final Rules Pauli Exclusion Principle: No more than____ electrons are in the same orbital Hund’s Rule: Orbitals of equal energy are each occupied by one electron before any orbital is combined with a second. (remember negative repels ______)

5.3 Physics and the Quantum Model Light: Energy that moves through space as a wave. Properties of waves: Wavelength  )- The distance from one wave crest to the next wave crest. Measured in mm, cm, or meters. Frequency (v)- The number of wave crests that pass a certain point each second. Measured in waves/sec, 1/sec or Hertz Speed (c)- How fast the wave travels through space. Light travels at a constant speed of x 10 8 m/sec.

You can do the algebra! Wavelength, Frequency and Speed are related to each other for any wave. (Wavelength)(Frequency) = Speed of light or ( ) (v) = c λ = c c= x10 8 m/s v Example: What is the wavelength of a light wave whose frequency is 5.5 x /sec? Example: What is the frequency of a light wave whose wavelength is 7.0 x meter?

The Electromagnetic Spectrum The Electromagnetic spectrum is all of the forms of light, both visible and invisible to our eyes x m 7 x m m 10 3 Wavelength as you move to the right. Energy as you move to the right. Gamma Ray X-RayUltra Violet Rays VioletViolet BlueBlue GreenGreen YellowYellow OrangeOrange RedRed Infra red Waves (heat) Micro waves Radio and TV Waves

How much energy does light have? Light moves through space as wave packets called “photons.” A photon is like a particle of light. Light’s energy can be determined by using: E = h v E= Energy v= frequency where h = Planck’s constant = x Joule(sec) photon Example: What is the energy of a photon whose frequency is 5.3 x /sec?

World in Motion: Wave Particle Duality 1. How do you prevent cellular damage by the use of x-rays? 2. Describe the Compton effect. 3. Give two equations from the movie and give the variables meaning. 4. How do you find the wavelength of a solid object?

Cornell Notes: Bohr Atom Model Atoms and light. 1. What is the difference between absorption lines and emission spectral lines? 2.If an atom releases light it must first gain something. What? 3.What happens to the electron when the atom gains energy? 4.Does the electron (atom) stay excited forever? What is released to stabilize the atom again? Bohr Atom I mportant points, supporting details. Write a two sentence summary about what you have learned.

Periodic Table: Properties of Elements DVD questions: 1.What does an element’s location on the “PT” tell you about? 2.Why are the elements on the end called Noble gases? 3.Going right across the PT, what happens to the charge? 4.What factors affect the size of an atom’s valence shell? 5.Low ionization energy leads to the loss of what? 6.Give the common trait of metals. Noble Gas Shorthand Activity-