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Chapter 7: Completing the Model of the Atom

Chapter 7: Completing the Model of the Atom. Class Activity (there is no BW). Send 1 student from your team to pick up enough white boards and markers for each person. 1 paper towel per team Draw a Bohr model for the element I assign to you. Class Activity (there is no BW).

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Chapter 7: Completing the Model of the Atom

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  1. Chapter 7: Completing the Model of the Atom

  2. Class Activity (there is no BW) • Send 1 student from your team to pick up enough white boards and markers for each person. 1 paper towel per team • Draw a Bohr model for the element I assign to you.

  3. Class Activity (there is no BW) 2. Now, find all other students with the same number of occupied energy levels. • Starting with Hydrogen’s group, stand together. Next, lithium’s group, finally sodium’s group. • What do you notice?

  4. Class Activity (there is no BW) 3. Now, find all other students with the same number of valence. • Starting with Hydrogen’s group, stand together. Then, Beryllium’s group, etc. • Then, boron’s group, etc. What do students notice?

  5. What the Periodic Table Tells Us 1. Columns are called “Groups” or “Families” • Main Group Elements are the tall ones! • Groups 1 & 2, 13-18 • They “follow the rules” pretty well. Behavior is predictable. • They tell us how many ______ the atoms of these elements have. • Groups #1&2 – Group # tells you how many • Groups 13-18- subtract 10 from the Group # • Transition Elements are in between Main Group Elements • Groups 3-12 • Behavior is less predictable! • Inner Transition Elements are at the bottom of the P. Table

  6. What the Periodic Table Tells Us 2. Rows are called “Periods” • They tell us the location of the _______ in atoms of these elements.

  7. Use the P. Table to Make an e- Diagram for an Element • Ex: Lithium • Identify its Group #: 1 • Identify its Period #: 2 Q: So how many valence e-s does a lithium atom have? And where are they located? A: 1 valence e- in the 2nd energy level

  8. Light: Electromagnetic Spectrum • Energy can travel in waves. • There are high energy and low energy waves. • The ones we can see are called “the visible spectrum.” ROY G BIV • Red is the low energy end: violet is the high energy end.

  9. Movement of e-’s • e-s can jump to higher energy levels if they absorb energy. • They can’t keep the energy so they lose it and “fall back” to lower levels. • When they do this, they release the energy they absorbed in the form of light.

  10. Movement of e-s, cont. • When e-s absorb energy, they do so in certain amounts. (They “jump” specific distances.) • When they release energy, they do so in certain amounts. (They “fall” specific distances.) And they release light that has that amount of energy. • Question: if e-s fall a long distance, they release a lot of energy. What is the color that is likely to be released? (red end or purple end of spectrum?)

  11. Emission Spectrum • Def: Each element has a characteristic set of colors that are given off when its e-s “fall back.” • You can identify an element by its emission spectrum! • Emission spectrum of hydrogen

  12. Emission Spectrum (cont.) • See Fig 7.4 on p 235 • H has 4 spectral lines (4 colored lines) • Mercury (Hg) has 11 lines! • Ne has 20+ lines! Problem: there are more lines than you would expect if there are only a few energy levels. Hypothesis: There must be many sublevels in an energy level

  13. Electron Sublevels Each electron has an “address,” where it can be considered to be located in the atom. • Main energy level= “hotel” • Sublevel = “floor” • Orbital = “room” • Regions of space outside the nucleus • All orbitals in a sublevel have the same energy • 2 electrons max can fit in an orbital

  14. Sublevels in Atoms • See Fig 7.5 on p 235

  15. Orbitals • s orbitals are spherical • There is only 1 orbital • p orbitals are dumbbell shaped • There are 3 orbitals, all with = energy • Each is oriented on either x, y, or z axis • They overlap • d orbitals have varying shapes • There are 5 orbitals, all with = energy • f orbitals have varying shapes • There are 7 orbitals, all with = energy

  16. Electron Configurations • Electrons are always arranged in the most stable (lowest energy) way • This is called“electron configuration”

  17. Section 2: The Periodic Table & Atomic Structure • Shape of p. table is based on the order in which sublevels are filled REGIONS OF THE P. TABLE (see p 244 of book) • s REGION (“block”) - Groups 1 & 2 • p REGION (block) - Groups 13-18 • d REGION (block)- Groups 3-12 (Transition Elements) • f REGION (block)- (Inner Transition Elements)

  18. List sublevels from lowest to highest energy level (Using P.Table) 1. Always start with Period 1-go from L to R. 2. Go to Period 2-from L to R 3. Go to Period 3- from L to R 4. Continue 4-7 periods, L to R until you have completed the P. Table. • Exception: elements in d block are 1 main E.L lower than the period where they are located • Exception: elements in f block are 2 main E.L.s lower than the period in which they are located

  19. Correct Order of Sublevels (lowest to highest energy) • 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

  20. Why Exceptions w/d & f block elements? • When you get to the higher main E.L.’s, the sublevels begin to overlap.

  21. E- configurations • Use the P. Table to write the sublevels in increasing order, as previously instructed. • Add a superscript next to each sublevel that shows how many e-s are in the sublevel • Ex: Oxygen: 1s22s22p4

  22. Valence e-s • Valence e-s are the electrons in the highest occupied main energy level. • Identify the valence e-s by finding the “biggest big number” in your e- configuration. Ex: Oxygen: 1s22s22p4 Question: WHAT IS THE BIGGEST BIG NUMBER YOU SEE? WHAT ARE THE VALENCE ELECTRONS?

  23. Noble Gas Notation • Short-cut way of showing e- configuration • A Noble Gas is a Group 18 element. • Identify the noble gas in the period above your element of interest. Write this symbol in brackets. • Write the e- configuration for any additional e-s that your element of interest has, but the noble gas doesn’t have. Ex: Nitrogen: 1s22s22p5 becomes [He] 2s22p5

  24. Practice Noble Gas Notation • Tungsten (W) • E- configuration • Noble Gas configuration

  25. Arrow Orbital Diagram-Used to show e- configuration. SYMBOLS: • A box represents an orbital • Label each box with the sublevel :1s 2s 2p 2p 2p • An arrow represents an electron • 2 arrows (e-s) in the same orbital face opposite directions. • Example: oxygen, see above ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↑

  26. Arrow Orbital Diagram-Used to show e- configuration. INSTRUCTIONS: • Fill electrons from lowest to highest sublevel. • Never place 2 e-s in the same orbital of a sublevel until you have placed one in each of the orbitals

  27. Arrow Orbital Diagram: Practice

  28. Regions or “Blocks” of the P. Table

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