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CHAPTER 6 ELECTRONIC STRUCTURE OF ATOMS. Almost everything we now know about electrons came from the study of light. Light is a type of electromagnetic radiation. Types of Electromagnetic Radiation. Three complete cycles of wavelength (l ).
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CHAPTER 6 ELECTRONIC STRUCTURE OF ATOMS
Almost everything we now know about electrons came from the study of light. Light is a type of electromagnetic radiation.
The product of the frequency (n), and its wavelength (l) equals the speed of light (c). c = ln
C = Since the speed of light is 3 x 108 m/s, there must be an inverse relationship between wavelength and frequency
The yellow light given off by a sodium vapor lamp used for public lighting has a wavelength of 589 nm. What is the frequency of this radiation?
The yellow light given off by a sodium vapor lamp used for public lighting has a wavelength of 589 nm. What is the frequency of this radiation? c =lnn = 5.09 x 1014 s-1
Max Planck assumed that small quantities of energy (quantum) can be emitted or absorbed as electromagnetic radiation. Planck’s constant (h) = 6.63 x 10-34 joule-seconds (J-s) E = hv
Since yellow light has a wavelength of 589 nm, what is the smallest quantum of energy that can be absorbed from yellow light?
Since yellow light has a wavelength of 589 nm, what is the smallest quantum of energy that can be absorbed from yellow light? E=hv E=(6.63 x 10-34)(5.09 x 1014) E = 3.37 x 10-19 J
Johann Balmer observed the 4 lines of the hydrogen spectrum to come up with a formula: v=C(1/22-1/n2) n= 3,4,5,6
Niels Bohr assumed that electrons orbit in circular paths around the nucleus. He also said that orbits of certain radii correspond to certain energies.
En=(-RH)(1/n2) n= 1, 2, 3, 4, … n= the principal quantum number RH = 2.18 x 10-18 J
Bohr assumed that electrons could “jump” from one energy state to another by absorbing or emitting energy of certain frequencies. E= Ef - Ei = hv
By combining some equations: v= E/h = (RH/h)(1/ni2-1/nf2) Calculate the wavelength of light that corresponds to the transition of the electron from the n=4 to n=2 state of the H atom.
Heisenberg’s UncertaintyPrinciple: It is impossible for us to know the exact velocity or exact location of an electron
This is a probability density of the location of the electron in a H atom. This represents the shape of the s orbital.