Electron Properties and Arrangement Chapter 5

1. Electron Properties and ArrangementChapter 5 Objectives: • Identify the properties of electrons. • Understand how electrons move in atoms. • Distinguish between atoms based on their different electron arrangements. .

2. Electrons in Atoms • What do you know about electrons in atoms? • Using Bohr’s model illustrate and label the sub-particles in the following neutral atoms: a. H-1 b. C-12 c. Ne-20

3. Electrons and Light Particles Similarities: • Very tiny particles • Extremely small masses • Move at very high speeds (3.0x108 m/s)

4. Electromagnetic Radiation Spectrum • Electromagnetic Spectrum : Divides light particles into regions based on their wave-like properties. • a. Relationship b/w wavelength and frequency? • Relationship b/w wavelength and energy emission? • Relationship b/w frequency and energy emission?

5. Wave-Like Properties: Wavelength • Wavelength: length of wave from two neighboring crest. • Amplitude: height of wave from origin to crest.

6. Wave-Like Properties: Frequency Frequency (Hz) : how many waves pass a certain point per second. Units: Hz (waves/second)

7. Wave-Like Properties: Energy • Temperature = energy emitted by light particles. • Photons = light particles that are classified by the amount of energy they emit off.

8. Electromagnetic Spectrum Analysis • 1 What light particle region has the longest wavelength? What light particle region has the lowest frequency? What light particle region emits the highest amount of energy? As wavelength decreases for a light particle, what happens to frequency? Sketch a line graph illustrating the relationship between wavelength and frequency. As frequency increases for a light particle what happens to it its energy? Sketch a line graph illustrating the relationship between frequency and energy. In the visible region, (ROYGBIV), does red or violet light particles have a slightly smaller wavelength?

9. Electromagnetic Spectrum Applications • “Electromagnetic Spectrum Song” by Emerson and Wong Yann

10. Electromagnetic Radiation Spectrum • a. Relationship b/w wavelength and frequency? • Relationship b/w wavelength and energy emission? • Relationship b/w frequency and energy emission?

11. Visible Region: Continuous Spectrum Continuous Spectrum = Presence of all light particles in the visible region.

12. Visible Region: Absorption Spectrum Absorption Spectrum = Presence of dark bands that indicate light particles absorbed by matter. • At room temperature we observe light particles reflected.by matter.

13. An Atom’s Interaction with Light Particles Light Particles Atom

14. Atoms Interaction with Light Particles Light Particles Atom Electrons absorb light particles • Electrons absorb specific light particles or photons. • Electrons that absorb photons can move to higher • energy levels.

15. Electron Movement 1. 2. 3. • Ground state of H Atom (lowest energy level for e-) • A photon (light particle) is absorbed by H’s electron. • Electron becomes excited and jumps to higher energy level. • 3. E- returns to ground state and emits (releases) the photon. • Emitted photon’s wavelength can be detected by scientists. • (Infrared region at room temp; Visble region at higher temps.)

16. Electron Movement 1. 2. 3.

17. Flame Test Lab Purpose: • Heat matter (atoms) so that we can observe the emission of photons from electrons.

18. Flame Test Lab Purpose: • Heat matter (atoms) so that we can observe the emission of photons from electrons. Conclusions: • Electron movement occurs instantaneously. • Elements’ electrons emit off different photons of energy and color. • Identify elements by the distinct color (photons) they emit off.

19. Bell Ringer: Electron Movement 1. Illustrate and explain the movement of electrons in an atom using the following terms: (photons, absorption, emission, energy levels, ground state, and excited state) • Rank the samples’ color based on the following: • Increasing wavelength. • Decreasing frequency. • Increasing emission of energy. 3. Which sample do you predict had electrons that moved the farthest during the flame test lab. 4. Explain how the flame test lab would be beneficial for forensic scientists.

20. Bell Ringer: Electron Movement 2. Rank the samples’ color based on the following: a. Increasing wavelength. (data table) *b. Decreasing frequency. (electromagnetic spectrum) *c. Increasing emission of energy. (electromagnetic spectrum)

21. Visible Region of EM Spectrum loke.as.arizona.edu

22. Electromagnetic Radiation Spectrum • a. Relationship b/w wavelength and frequency? • Relationship b/w wavelength and energy emission? • Relationship b/w frequency and energy emission?

23. Bohr’s Model of the Atom The electron cloud consists of energy levels. Electrons reside and move around in these energy levels. Electrons can move to other energy levels when absorb photons.

24. Electron Movement 1. 2. 3. • Ground state of H Atom (lowest energy level for e-) • A photon (light particle) is absorbed by H’s electron. • Electron becomes excited and jumps to higher energy level. • 3. E- returns to ground state and emits (releases) the photon. • Emitted photon’s wavelength can be detected by scientists. • (Infrared region at room temp; Visble region at higher temps.)

25. Infinite Campus Update • Flame Test Lab *Quiz tomorrow over electron properties, wave-like properties, and electron movement.

26. Electron Movement 1. Explain the difference between the ground state and the excited state of an electron in an atom. 2. In the flame test lab, the color change occurred when electrons ________ photons and dropped down to an energy level closer to the nucleus. (absorbed, reflected, emitted)

27. Continuous Spectrum Review Continuous Spectrum = Reflection of all light particles by electrons in the visible region. Ex. sun; white light bulbs

28. Visible Region Absorption Spectrum Absorption Spectrum =Reveals what light particles are reflected and absorbed by electrons.

29. Emission Spectrum Emission Spectrum =Reveals what photons are emitted during electron movement. Ex. Hydrogen Light chemed.chem.purdue.edu

30. Emission Spectrums • Emission spectrum for each element is unique.

32. Emission Spectrums • Emission spectrum for each element is unique.

33. Quantum of energy: • Specificenergy that is absorbed or emitted by electrons. • Energy difference between two energy levels. • Scientist can calculate energy emitted by electrons. • Determine what energy levels electrons move between in an atom. Electron Movement in Energy Levels

34. Locating an Electron Is it possible to know the exact location and velocity of an electron at any instant in time? Very difficult to locate an electron because: - moving extremely fast -continuously bombarded by light particles When locate an electron with a photon from a microscope, it changes its velocity in unpredictable ways.

35. Heisenberg Uncertainty Principle After Before Photon changes wavelength Photon It is not possible to know the exact position and velocity of an electron at the same time.

36. Electron Movement and Arrangement • What principle states that you cannot know the location and velocity of an electron at the same time? • Why is an emission spectrum unique for each element? • What is quantum energy?

37. Electron Movement and Arrangement • What principle states that you cannot know the location and velocity of an electron at the same time? • Why is an emission spectrum unique for each element? • What is quantum energy? • What is the quantum mechanical model? • What is the maximum number of electrons on the 5th energy level?

38. The Quantum Mechanical Model • An atomic model that best explains the probablearrangement and movement of electrons at any moment in time. • Schrodinger provided evidence for this model using a complex mathematical equation. • Depends upon 4 quantum numbers. Erwin Schrodinger

39. n-Quantum Number n = energy levels • 3-D region of space around the nucleus where an electron can be found. • Each energy level has a specific energy value. • E- must absorb or release a specific quantum of energy to move between energy levels. • E- do not travel in an orbit (exact path) around the nucleus. Atomic orbitals:Probable paths an electron would take around the nucleus.

40. Energy Levels and the Periodic TableAssociate energy levels with rows on periodic table.

41. n-Quantum Number • Limited number of electrons on each energy level. • 2n2 Rule determines the maximum number of electrons on each energy level.

42. l–Quantum Number l -number : • Sublevels within an energy level. • Sublevels identify the shape of the orbitals. • There are four different sublevels: s, p, d, f

43. Orbital Shapes A maximum of 2 electrons can move in each orbital.

44. Infinite Campus Update • Electron properties and movement quiz (10pts.) • Flame Test Lab (15 pts.) Due Today: Electron Probability Lab (15pts.)

45. Bell Ringer: Electron Arrangement 1. What atomic model best explains electron arrangement? 2. a. What is the n-quantum number? b. T or F: Electron move around the nucleus in an exact path. 3. a. What is the l-quantum number? b. Illustrate the s, p, d, f atomic orbitals? c. How many electrons can move in each atomic orbital at any one time?

46. Orbital Shapes A maximum of 2 electrons can move in each orbital.

47. Orbitals and Energy Requirement • Electron movement defines orbital shapes for each sublevel. • Electrons need energy to move in orbital shapes.

48. Electron Sublevels (atomic orbitals) Diagonal Rule • Use the diagram to determine the type • of sublevels (orbitals) in each energy level? • 1st: • 2nd: • 3rd: • 4th: • 5th: • 6th: • 7th: • What is the maximum number of • electrons in each sublevel? • What do you suppose the yellow • arrows represent? khanacademy.org

49. m- Quantum Number m –number: • Orientations for each atomic orbital. • Orbital orientations: The different ways an electron can make an orbital in 3-D space.

50. S-Orbital Orientation • Maximum # of s-orbital electrons on an energy level? • How many s-orbitals are possible on an energy level?