ATOMIC STRUCTURE ELECTRON CONFIGURATION 10/13/15 PROJECT DATE. Tuesday, October 13, 15

Transcription

1 PROJECT DATE ATOMIC STRUCTURE ELECTRON CONFIGURATION 10/13/15

2 Agenda Begin Topic 2.2 Electron Configuration Homework: Energy of waves calculations Due tomorrow! Yes - tomorrow

3 Atomic Structure The nuclear atom Electron Configuration Ms. Thompson - Honors Chemistry Wooster High School

4 Topic 2.2 Electron configuration Emission spectra are produced when photons are emitted from atoms as excited electrons return to a lower energy level. The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels, which converge at higher energies. The main energy level or shell is given an integer number, n, and can hold a maximum number of electrons, 2n2. A more detailed model of the atom describes the division of the main energy level into s, p, d and f sub-levels of successively higher energies. Sub-levels contain a fixed number of orbitals, regions of space where there is a high probability of finding an electron. Each orbital has a defined energy state for a given electronic configuration and chemical environment and can hold two electrons of opposite spin.

5 Electron Configuration The electromagnetic spectrum Electromagnetic spectrum consists of all wavelengths of light: gamma rays, x-rays, ultraviolet, visible light, infrared, microwaves, and radio waves Higher energy waves (gamma/x-rays) have small wavelengths where-as low energy radiation (radio/microwaves) have longer wavelengths. Wavelength and frequency are related through the following relationship: c = v λ E = joules λ = meters (m) v = Hertz (Hz) c = speed of light (3.00 x 10 8 m s -1 )

6 Electron Configuration The electromagnetic spectrum

7

8 Electron Configuration The electromagnetic spectrum Absorption, emission, and continuous spectra When a pure gaseous element is subjected to an electrical discharge, it will emit radiation. This results in an an emission spectrum which consists of a series of lines against a dark background. i.e. hydrogen

9 Electron Configuration Emission spectra and Bohr s theory of the hydrogen atom Each element has its own characteristic line spectrum which is used to identify the element Lines in emission spectrum have specific wavelengths which corresponds to a discrete amount of energy Quantization: Discrete packets of electromagnetic radiation A Photon is a quantum of radiation E = hv = hc/λ h = Planck s constant = 6.63 x J s v = frequency of radiation c = speed of light = 3.00 x 10 8 m s -1 Energy of a photon

10 Practice Problem... I Do... A certain electromagnetic wave has a wavelength of 625 nm. a.) What is the frequency of the wave? First, convert nm to m: 625 nm x 10-9 m = 6.25 x 10-7 m 1 nm Second, calculate frequency using the equation: v = c/λ= 3.00 x 10 8 m s x 10-7 m = 4.80 x 1014 s -1 c = speed of light = 3.00 x 10 8 m s -1

11 Energy'of'Waves' Key$formulas:$ 1. c=νλ' 2. E=hν'!'hc/λ' 3. E=mc 2 ' 4. E=RZ 2 (1/n 12 ' '1/n 22 )' Where$ λ'='wavelength'in'm' ν'='frequency'in's E1 ' c'='speed'of'light'='3.00'x'10'm's E1 ' h'='planck s'constant'='6.63'x'10 E34 'J's' R'='Rydberg'constant'='2.18'x'10 E18 'J' Z'='atomic'number' n 1 'and'n 2 'are'quantum'numbers' N'='Avogadro s'number'='6.02'x'10 23 ' mol E1' '

12 Do#on#a#separate#piece#of#paper # KXL#a#local#am#radio#sta5on#broadcasts#on#a#frequency#of#750# kilohertz.#(750,000#s C1# )#Calculate#the#wavelength#and#energy#of# the#radio#wave#emijed#by#kxl.## Ultra#violet#radia5on#from#the#sun#is#oLen#quite#intense#in#the# range#of#320c400#nanometers.#calculate#the#frequency#and# energy#of#uv#radia5on#if#its#wavelength#is#360#nm.## An#argon#laser#emits#light#with#a#wavelength#of#489#nm.#Calculate# its#energy#in#kilojoules#per#mole.## A#laser#emits#light#with#a#frequency#of#4.69#x#1014#s C1.#Calculate# its#energy#in#kilojoules#per#mole## In#a#spectra#experiment,#a#line#for#the#red#line#of#hydrogen#was# recorded#at#645#nm.#calculate#its#frequency#and#energy#in#kj#per# mole.##

13 Topic 2.2 Electron configuration Emission spectra are produced when photons are emitted from atoms as excited electrons return to a lower energy level. The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels, which converge at higher energies. The main energy level or shell is given an integer number, n, and can hold a maximum number of electrons, 2n2. A more detailed model of the atom describes the division of the main energy level into s, p, d and f sub-levels of successively higher energies. Sub-levels contain a fixed number of orbitals, regions of space where there is a high probability of finding an electron. Each orbital has a defined energy state for a given electronic configuration and chemical environment and can hold two electrons of opposite spin.