Light, Waves, and Electrons Light: Travels 1. 2. Light Waves Wavelength Frequency
Electromagnetic Spectrum Speed of light The product of frequency of a wave and wavelength = the speed of light Calculate the wavelength of the yellow light emitted by a sodium lamp if the frequency of the radiation is 5.09 X 10 14 Hz
Calculate the frequency of a wave that has a wavelength of 5.77 X 10-3 cm. What is the wavelength of a wave that has a frequency of 4.17 X 10 14 Hz? What is the color of this light? Energy: The amount of energy absorbed or emitted by matter is proportional to the frequency of the radiation. Energy is proportional to frequency Plank s constant = 6.626 X 10-34 J/S Calculate the amount of energy in joules of light with a frequency of 4.40 X 10 13 Hz.
Calculate the amount of energy in joules of light with a wavelength of 6.38 X 10-7 m Calculate the amount of energy in joules of light with a wavelength of 1.76 X 10-4 cm Electrons in an atom can absorb energy. They become excited and go to an excited state. They then go back to ground state, releasing energy (visible light). Spectroscopy: producing and analyzing spectra. Uses a spectroscope to identify substances.
Analogy: Think of the nucleus as the planet and the electrons make up the atmosphere. They essentially make up a cloud around the nucleus. This cloud is made up of energy levels. Each level is made up sublevels.
o o o o 1 st energy level has 1 sublevel ( s sublevel) 2 nd energy level has 2 sublevels ( s and p sublevels) 3 rd energy level has 3 sublevels ( s, p, and d sublevels) 4 th energy level has 4 sublevels ( s, p, d and f sublevels) http://www.youtube.com/watch?v=k-jngq16jey Atomic orbitals areas where electrons are likely to be found. s orbital only 1 s orbital per sublevel p orbital 3 p orbitals per sublevel d orbital 5 d orbitals per sublevel f orbital 7 f orbitals per sublevel The organization of the periodic table makes it EASY to determine the orbitals of the electrons for each atom.
Rules for writing orbital notations 1. When writing orbital notations, use one arrow to represent each electron. 2. Electrons must enter the lowest energy sublevel possible before moving to a higher energy sublevel (Aufbau principle) 3. an atomic orbital may hold at most two electrons a. Electrons within the same orbital have opposite spins. (Pauli exclusion principle) 4. one electron must be put in each orbital of a sublevel before any one orbital can have two electrons in it. (Hund s rule) 5. Even if you don t have enough electrons to fill each orbital of a sublevel, you must still show that those orbitals exist.
6. The total number of arrows (electrons) must be equal to the atomic # for each element. Write the orbital notation for oxygen. Step 1: How many electrons does oxygen have? Step 2: What orbital level range will the electrons occupy? Step 3: Place one electron in each sublevel before adding a second arrow to each sublevel.
Write the orbital notation for aluminum. Step 1: How many electrons does aluminum have? Step 2: What orbital level range will the electrons occupy? Step 3: Place one electron in each sublevel before adding a second arrow to each sublevel. Electron Configurations the way in which electrons are arranged around the nucleus of an atom. Each configuration has 3 parts: 1s 2 1 represents the energy level s represents the sublevel 2 represents the number of electrons in that sublevel * The total of superscripts is equal to the atomic number for the element. Which element is represented by the following electron configuration: 1. 1s 2 2s 2 2p 6 3s 2 3p 6 2. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 1
Exceptions: Write the electron configuration for the following elements: 1. Sulfur 2. Gallium 3. Thorium 4. Platinum
5. Silver 6. gold Noble gas configurations are used as a shorthand for long electron configurations. Find the noble gas before the element you are writing the configuration for, put it in brackets, and then start with the next s sublevel to fill out the rest of the configuration. Write the noble gas configuration for the following elements: 1. Sulfur 2. Gallium 3. Thorium 4. Platinum 5. Silver 6. gold
7. What element is represented by the following noble gas configuration: 1. [Kr]5s 2 4d 10 5p 2 2. [Ar]4s 2 3. [Xe]6s 2 5d 1 4f 12