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Do Now (5 min)

Do Now (5 min). Using COMPLETE SENTENCES, explain why electrons are important (What do they do?). HAPPY THURSDAY! 12/3/09 Cornell Notes Practice Worksheet Partner Practice. Valence Electrons. Why are electrons important?. Electrons are responsible for HOW ELEMENTS REACT

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Do Now (5 min)

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  1. Do Now (5 min) Using COMPLETE SENTENCES, explain why electrons are important (What do they do?)

  2. HAPPY THURSDAY! 12/3/09 Cornell Notes Practice Worksheet Partner Practice Valence Electrons

  3. Why are electrons important? • Electrons are responsible for HOW ELEMENTS REACT • That is why we learned how to: • Write electron configurations • Draw electron orbital diagrams • When we understand electrons • we can predict how elements will behave (what we can do with them) • Understand the structure of the periodic table

  4. Valence Electrons • The specific electrons responsible for the chemical properties of an element • Electrons in an atoms outermost orbitals • They are in the highest energy levels

  5. Counting the Number of Valence Electrons 1. Write the electron configuration O8 1s2 2s2 2p4 2. Circle the subshells in the highest energy levels O8 1s2 2s2 2p4 3. Count the electrons in those orbitals O8 1s2 2s2 2p4 + 6 2 4 =

  6. Worksheet Example #1 How many valence electrons does Magnesium have? 1. Write the electron configuration 2. Circle the subshells in the highest energy level 3. Count the electrons in those orbitals Mg12 1s2 2s2 2p6 3s2 2!

  7. Worksheet Example #2 How many valence electrons does Chlorine have? 1. Write the electron configuration 2. Circle the subshells in the highest energy level 3. Count the electrons in those orbitals Cl17 1s2 2s2 2p6 3s2 3p5 7! 2 + 5 =

  8. Electron Dot Structures Used to represent the valence electrons in an element 1. Draw the element SYMBOL 2. Dots representing electrons are placed around the four sides of the symbol one at a time Oxygen 6 valence electrons O

  9. Example #3 What is the electron dot structure of Magnesium? What’s the symbol of magnesium? How many valence electrons? 2 Mg

  10. Example #4 What is the electron dot structure of Chlorine? What’s the symbol of chlorine? How many valence electrons? 7 Cl

  11. Key Points • Valence electrons are responsible for how elements react • Elements in the same group have the SAME NUMBER OF VALENCE ELECTRONS – that’s why they have similar properties

  12. Grab-It-Challenge • You’ll be working on your own • Select one activity card at a time • Write down which activity card you select • Complete the problems on a separate sheet of paper • When you are finished, have Ms. Akagi check it • Once it’s correct, you can grab a new card • Full credit = two cards done • Bonus points for three or more cards

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