1. Light and Energy Electromagnetic Radiation is a form of energy that emits wave-like behavior as it travels through space. Examples: Visible Light Microwaves X-rays Radio waves

2. Light and Energy Several characteristics can be used to describe these waves. Wavelength ( ) is the shortest distance between equivalent points on a continuous wave. Amplitude (a) is the height of a wave from the origin to the cresting point. Frequency ( ) is the number of waves that pass a given point per second. 2 sec Time

3. Light and Energy Which of the following waves has a higher frequency?

4. Light and Energy Electromagnetic radiation can be displayed in the electromagnetic spectrum. This spectrum places all of the wave types in order based on wavelength ( ) and frequency ( ).

5. Light and Energy All electromagnetic waves travel at the same speed in a vacuum This speed (c) is 3.00 x 10 8 m/s in a vacuum. c is more commonly referred to as the speed of light. c =

6. Sample Problem Green light has a wavelength of 545nm. What is its frequency?

7. Light and Energy In 1900 Max Planck helped us move toward a better understanding of electromagnetic radiation. Matter can gain or lose energy only in small, specific amounts called quanta. A quantum is the minimum amount of energy that can be gained or lost by an atom.

8. Light and Energy Planck then demonstrated the relationship between that quantum and the frequency of the emitted radiation. E = h E = energy = frequency h = Planck’s Constant 6.626 x 10 -34 J s

9. Atomic Emission Spectrum Electrons gain energy and ‘jump’ to a higher energy level. This is an unstable excited state. The electrons release energy when they return to their ground state. We see this energy as light.

10. Atomic Emission Spectra

11. The Bohr Quantum Model The electron in a hydrogen atom moves around the nucleus only in certain allowed circular orbits Ground State: The lowest possible energy level. Excited State: Higher energy level.

12. Light and Energy Light and energy can’t always be explained using waves. In 1905 Albert Einstein proposed that electromagnetic radiation has both wavelike and particle like natures. While a beam of light has many wavelike characteristics, the beam can also be thought of as a stream of tiny particles or bundles of energy called photons. A photon is a particle of electromagnetic radiation with no rest mass that carries a quantum of energy.

13. Wave-Particle Duality Theory Is energy a wave like light, or a particle?  BOTH

14. Atomic Theory Louis de Broglie (1892 – 1987) Matter has characteristics of both waves and particles Electrons move in wavelike motion in the circular orbits

15. Heisenberg Uncertainty Principle There is a fundamental limitation to just how precisely we can know both the position and momentum of a particle at a given time Watch this video!

16. Schrodinger Came up with an equation to describe the probability of finding an electron within a 3D area of space. These equations are called wavefunctions. The wavefunctions describe orbitals. Orbitals are the building block of electron arrangement.

17. The Quantum Model! Atomic orbitals are used to describe the possible position and energy of an electron.

18. Orbitals The location of an electron is described with 4 terms. - Energy Level - Sublevel - Orbital - Spin

19. Energy Level Describes the energy and distance from the nucleus. Whole numbers, ranging from 1 to 7.

20. Orbital Shapes – s sublevel - An orbital can contain up to 2 electrons. - The s sublevel contains only 1 orbital.

21. P Sublevel 3 orbitals present in this sublevel. Each orbital can only have 2 electrons.

22. D Sublevel 5 orbitals present in this sublevel.

23. F Sublevel 7 orbitals present in this sublevel.

24. s sublevel p sublevel d sublevel f sublevel

25. Summary Energy Level Sublevels Present # of Orbitals Total # of electrons in Energy Level 1 2 3 4

26. Arrangement of E- Electrons are arranged according to a few rules. –Aufbau Principle –Pauli’s Exclusion Principle –Hund’s Rule

27. Aufbau Principle As protons are added one by one to the nucleus to build up the elements, electrons are similarly added to orbitals Electrons fill in low energy orbitals before high energy orbitals

28. Aufbau Principle Increasing energy 1s 2s 3s 4s 5s 6s 7s 2p 3p 4p 5p 6p 3d 4d 5d 7p 6d 4f 5f He with 2 electrons * orbital energy order found on periodic table

29. s sublevel p sublevel d sublevel f sublevel

30. Pauli’s Exclusion Each orbital can only hold 2 electrons and they will have opposite spins. –Example

31. Hund’s Rule When there are multiple orbitals, one electron goes in each before pairing takes place.

32. Practice Step 1: Start by drawing out the orbitals in the correct order. Step 2: Determine the total number of electrons.

33. Practice Step 3: Start arranging the electrons Step 4: Follow the rules!

34. Electron Configuration Electron configuration is a shortcut to the orbital notation. It is done by writing only the energy level and sublevel. The number of electrons in each is represented by an exponent.

35. Noble Gas Shortcut Uses noble gases to represent the ‘inner’ electrons. Noble gases are the last column on the right. Step 1: Find noble gas on the row above the element. Step 2: Write remaining configuration.

36. Valence Electrons Are the electrons found on the highest energy level. Remember, the energy level is represented by the whole number. How do we find them?

37. Valence Electrons Practice –Fe –Cu –Ag Do you see a pattern?

38. Lewis Dot Diagrams A Lewis Dot diagram shows the number of valence electrons in an atom. You put the element symbol and dots around it to represent the valence electrons.