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Catalyst – March 6+2, 2012 Remember, this is on your own paper 

Catalyst – March 6+2, 2012 Remember, this is on your own paper . What is ONE difference between an element and a compound? What is ONE difference between ionic and covalent compounds? (Use your book if you need to!). Today’s Agenda. Catalyst Welcome to Unit 3!!! Notes

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Catalyst – March 6+2, 2012 Remember, this is on your own paper 

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  1. Catalyst – March 6+2, 2012Remember, this is on your own paper  • What is ONE difference between an element and a compound? • What is ONE difference between ionic and covalent compounds? (Use your book if you need to!)

  2. Today’s Agenda • Catalyst • Welcome to Unit 3!!! • Notes • Lewis Dot Structures • Stable Ions and Oxidation Numbers • Octet Rule • Exit Question HW: Workbook Pages 83-85

  3. Today’s Objectives • SWBAT describe a chemical bond. • SWBAT draw Lewis Dot Structures for atoms and ions. • SWBAT use the octet rule to predict the stable ion an atom will form in a chemical bond.

  4. Unit 3: Chemical Hook-Ups • In this unit, you will be learning about how atoms hook-up, or bond. The unit will include… • Lewis Dot Structures: Octet Rule, Stable Ions, Number of Bonds • Ionic Compounds vs. Covalent Compounds • Formulas and Names for Compounds • Chemistry.com profile and Speed Dating

  5. NOTES: Intro to Bonding

  6. What is a compound? Key Point #1: A compound results from interaction between valenceelectrons of different atoms.

  7. Bonding • Key Point #2: There are two main ways that valence electrons interact between atoms to create chemical bonds: • By completely transferring them to another element  Ionic Bond • By sharing electrons with another element  Covalent Bond

  8. Chemical Bond Spotlight: NaCl (table salt) 2 different elements: • Sodium (Na) • Chlorine (Cl) 1 compound: • Sodium chloride (NaCl) Na Cl NaCl

  9. NOTES: LEWIS DOT STRUCTURES!

  10. Valence Electrons SODIUM HAS 1 VALENCE ELECTRON ALL TOGETHER, SODIUM HAS 11 ELECTRONS. P=11 N=12 NUCLEUS Valence electrons are the electrons in the outermost energy level

  11. Don’t Forget! Valence Electrons • Electrons in the outermost level or shell of the atom are the ones that determine the chemical reactivity of an element • Outer s and p electrons • These electrons are involved in bonding

  12. Lewis Dot Structures Key Point #3: Lewis Dot Structures only show the number of valence electrons in an atom. • Valence electrons are the only electrons involved in bonding • Valence electrons are the most important electrons

  13. Drawing Lewis Dot Structures • Write element symbol. • Determine number of valence electrons. • Place single dot on right side and add single dots counterclockwise. EXAMPLES COMING UP…

  14. LDS Example 1: Sodium (Na) • Write element symbol. • Determine number of valence electrons. • Place single dot on right side and add single dots counterclockwise.

  15. LDS Example 2: Neon (Ne) • Write element symbol. • Determine number of valence electrons. • Place single dot on right side and add single dots counterclockwise.

  16. You try! • Boron • Oxygen • Lithium

  17. Lewis Dot Sructures What do the Lewis Dot Structures have in common?!?!?

  18. I have a couple QUESTIONS… • What kind of charge does an electron have? • (-1) • What kind of charge does an entire atom have? • Neutral (positives = negatives)

  19. First thing you need to know about ionic bonds…. • Key Point #4: An ion is an atom that has gained or lost anelectron.Cation = positive ion (+) Anion = negative ion (-) + -

  20. Types of ions • Cation – a positive ion (+) • “t” looks like (+) • Anion – a negative ion (-) • “n” or onion for negative

  21. Formation of Negative Ions (ANIONS) • Imagine that electrons are pieces of poop • Is poop is flying into your yard (an atom’s energy levels) a positive or negative thing? • So…if poop lands in your yard, are you more positive or more negative? - So…NEGATIVE ions are formed when an atom GAINS one or more electrons!

  22. Formation of Positive Ions (CATIONS) • Imagine that electrons are pieces of poop • Is poop in your yard (an atom’s energy levels) a positive or negative thing? • So…if you get rid of the poop in your yard, are you more positive or more negative? + So…POSITIVE ions are formed when an atom LOSES one or more electrons!

  23. Practice Questions • If an atom gains an electron it will have a ___________ charge. • If an atom loses an electron it will have a ___________ charge. • If chlorine gains 3 electrons it will have a _______ charge. NEGATIVE POSITIVE 3-

  24. Cl loses 4 Electrons What is the stable ion? Ions!

  25. Cobalt gains 2 electrons What is the stable ion? Ions!

  26. Si3- What happened… gain or lose…how many? Ions!

  27. Si3- Silicon gains 3 electrons How many total electrons does Si have now? Ions

  28. Practice Problems – Write all down! • Write down the stable ion that will form for the following: • Sr gains 5 electrons • Phosphorous loses 1 electron • Then, answer how many electrons TOTAL will they have now?

  29. Practice Problems – Write all down! How many TOTAL electrons do the following ions have? • Cl2+ • Li2- • Xe3+ • O1- • Zn5-

  30. Octet Rule • What is different about the valence shells of the elements on the Left and those on the Right? • The noble gases have full valence shells, the other atoms do not… Octet Rule – Elements are most stable when they have the electron configuration of a noble gas (Key Point next…)

  31. 8 Octet Rule 8 • Key Point #5: The octet rule says that atoms are most stable when they have a full valence shell (2 or 8 valence electrons). • Atoms can gain, lose, or share electrons to become stable (happy)  • Atoms with 5 or more valence electrons will GAIN electrons to become stable (happy)  • Atoms with 3 or less valence electrons will LOSE electrons to be stable (happy)  8 8

  32. Octet Rule - Examples • How many electrons will the following atoms gain or lose to become stable (happy)? How many TOTAL electrons will the atom then have? What is the STABLE ION? • F • Se • N • Ca

  33. Octet Rule – Examples

  34. Need extra practice? Try these… • How many electrons will the following atoms gain or lose to become stable (happy)? How many TOTAL electrons will the atom then have? What is the STABLE ION? • P • Kr • Ca • I • K

  35. Worksheet for Class or HW Half Shee – eet! Take care of your bidness and complete it tonight!

  36. Exit Question • Anion = _______ charge, Cation = _______ charge • What is the STABLE ION that will form for the following elements? Say how positive or negative it will be. • Te • Draw the LDS for the following elements • Magnesium HW: Workbook Pages 83-85 Unit 2 Test Corrections due tomorrow!

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