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Ch 22 Chemical Bonds

Ch 22 Chemical Bonds. Tuesday 10.7.14. Stability. Some elements combine chemically and no longer have the same PROPERTIES they did before becoming a compound Na + Cl  NaCl (explosive metal + poisonous gas = table salt) http:// www.youtube.com/watch?v=2mzDwgyk6QM. Stability.

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Ch 22 Chemical Bonds

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  1. Ch 22Chemical Bonds • Tuesday 10.7.14

  2. Stability • Some elements combine • chemically and no longer have • the same PROPERTIES they • did before becoming a compound • Na + Cl  NaCl • (explosive metal + poisonous gas = table salt) • http://www.youtube.com/watch?v=2mzDwgyk6QM

  3. Stability • A CHEMICAL FORMULA is • composed of symbols and subscripts indicating the number of atoms of an element in a compound. • NaCl 1 Sodium 1Chloride • Mg3N2 3Magnesium 2 Chloride • AlCl3 ?Aluminum ? Chloride

  4. Try these 1 Hydrogen, 2 oxygen Hydrogen, oxygen Copper, sulfur, oxygen 1Copper, 1 sulfur, 4 oxygen Hydrogen, carbon, oxygen 22 Hydrogen, 12 carbon, 11 oxygen Magnesium, sulfur, oxygen 1 Magnesium, 1 sulfur, 4 oxygen 1 Calcium,2 nitrogen, 6 oxygen Calcium, nitrogen, oxygen

  5. Stability • Atoms form compounds when the • compound is more STABLE • than the separate atoms. • (Sodium and Chlorine)

  6. Stability • Noble Gases are more • CHEMICALLYSTABLE than • other elements because they • have a complete outer energy level. • Elements that do not have full energy levels are more stable in COMPOUNDS. • Atoms can lose, gain or SHARE electrons to get a stable outer energy level.

  7. Checkpoint 1 2 3 How did you determine what an full outer shell was? • A full outer shell is the electron configuration of the closet noble gas. Usually 8 (unless its close to Helium) How many electrons would these elements need to gain to have a full outer shell? Chlorine? Oxygen? Nitrogen?

  8. Checkpoint 1 2 3 Lithium? Magnesium? Aluminum? How did you determine what an full outer shell was? • A full outer shell is the electron configuration of the closet noble gas. Usually 8 (unless its close to Helium) How many electrons would these elements need to lose to have a full outer shell?

  9. Stability • A CHEMICAL BOND is the • force that holds atoms together. • Some bonds are so strong that energy is released when the bond is broken. • https://www.youtube.com/watch?v=YclI0lAFXmM

  10. Types of Bonds An ION is a charged particle because it has more or fewer electrons than protons. When an atom LOSES an electron, it becomes a positively charged ion; a superscript indicates the charge. Li +, Be 2+ , Al 3+

  11. Types of Bonds When an atom GAINS an electron, it becomes a negatively charged ion. CL-, O 2-, N 3-

  12. Checkpoint lost 3 gained 2 1 lost gained 1 How many electrons have been gained or lost?

  13. TYPES OF BONDS • The result of this bond is a NEUTRAL compound. • The sum of the charges on the ions is ZERO An ionic compound is held together by the IONIC BOND- the force of attraction between opposite charges of the ions.

  14. Types of Bonds • MOLECULES are neutral • particles formed as a result of • sharing electrons

  15. Types of Bonds • A COVALENT BOND is the • force of attraction between • atoms sharing electrons. • Atoms can form double or triple BONDS depending on whether they share two or three pairs of electrons.

  16. Types of Bonds • Electrons shared are held • MORE CLOSELY to the atom • with the larger nucleus.

  17. Types of Bonds Polarity is responsible for waters unique properties: http://www.youtube.com/watch?v=VhWQ-r1LYXY survival of sea life? http://www.youtube.com/watch?v=ASLUY2U1M-8 • A POLAR molecule has one end that is slightly negative and one end that is slightly positive --- although the overall molcule is nuetral

  18. Types of Bonds • In a NONPOLAR molecules • electrons are shared equally. What are the formulas for the compounds shown? Fluorine Gas Benzene Carbon Tetrafluoride

  19. Check in • Predict if which compound • would be ionic and which would • be covalent • CO2 • LiF • Cl2 • AlBr3 • Covalent • Ionic • Covalent • Ionic

  20. Writing Formulas • Chemists use SYMBOLS fro the • periodic table to write formulas for • compounds. • A BINARY COMPOUND is composed of 2 elements. • EX: HF, MgCl2,Al2O3 • OXIDATION NUMBER –how many electrons an atom has gained, or lost, or shared to become stable

  21. Writing Formulas Use oxidation numbers and their least common multiples to write FORMULAS. When writing formulas, remember that the compound is NEUTRAL. A formula must have the correct number of positive and negative ions so the charges BALANCE

  22. Writing Formulas • 2 H and 1 O formula H2O • 1 Mg and 2 Cl formula MgCl2 • 3 Ca and 2 N formula Ca3N2 Example: In what ratio should H+ and O2- combine? In what ratio should Mg2+ and Cl- combine? In what ratio should Ca2+ and N3- combine?

  23. Writing Formulas • Hydrogen Fluoride • Magnesium Chloride • Aluminum Oxide Use the name of the first element, the root name of the second element, and the suffix “ide” to write the NAME of a binary ionic compound. EX: HF MgCl2 Al2O3

  24. Formulas and Compounds SO42- Sulfate, PO43- Phosphate MgSO4Magnesium Sulfate Li3PO4 Lithium Phosphate POLYATOMIC ION– positively or negatively charged, covalently bonded group of atoms. The compound contains THREE or more elements. To write names, write the name of the POSITIVE ion first; then write the name of the NEGATIVE ion.

  25. Formulas and Compounds ONE Ca2+ and TWO NO3- formula = Ca(NO3)2 • To write the FORMULA, use • oxidation numbers, determine • their least common multiple, • and put parenthesis around the polyatomic ion before adding subscripts • EX: Write the formula for bonding of Ca2+ and NO3-

  26. Formulas and Compounds HYDRATE – compound with water chemically attached to its ions.

  27. Formulas and Compounds CO2 Carbon Dioxide C2H4DicarbonTetrahydride Name covalent compounds by using PREFIXES to indicate how many atoms of each element are in the compound.

  28. Homework • Write out and answer CH22 • sect1 review questions

  29. Transitional Page

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