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Chemical Bonds Unit 6 Chapter 6

Chemical Bonds Unit 6 Chapter 6. COVALENT. METALLIC. IONIC. I. Why do atoms bond?. A. Atoms bond in order to become stable B. Electron configurations of the noble gases are stable. 1. Helium is stable with 2 valence e - . 2. All others are stable with 8 valence e - .

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Chemical Bonds Unit 6 Chapter 6

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  1. Chemical BondsUnit 6Chapter 6 COVALENT METALLIC IONIC

  2. I. Why do atoms bond? A. Atoms bond in order to become stable B. Electron configurations of the noble gases are stable. 1. Helium is stable with 2 valence e-. 2. All others are stable with 8 valence e-. C. Atoms of unstable electron configurations will gain, lose, or share electrons to become stable like a noble gas.

  3. notstable stable stable notstable

  4. Al Ca F Cs II. Electron Dot Notation • A. Only valence electrons are used in bonding • B. Electron dot notation highlights the • valence electrons

  5. 8 1 2 3 4 5 6 7 Representative Group Valence Electrons

  6. As As YES! As As How to draw the electron dot notation of an atom: As Step 1: Write the chemical symbol Step 2: Imagine a box around it Step 3: Draw a dot for each valence electron Dots only go on the SIDES of the box Rule: One dot per side before you double up

  7. Now you try some. Li Cl Ne Sr C Mg Pb N I

  8. What would happen if sodium and chlorine bump into each other? Net charge -1 Net charge +1 An electron would transfer from the Na atom to the Cl atom so that each atom would become a stable ion.

  9. III. Ionic Bonds • A. Metal – Nonmetal • B. Electrons are transferred from the metal • to the nonmetal • C.Ions are produced • D. Ion attraction makes the bond • (+) (-) Na+1 Cl-1

  10. E. A Crystal is formed

  11. I Let’s Practice! Before bonding After Bonding Chemical Formula -1 +1 K Br K Br KBr Ion net charge = zero! -1 +2 Ca I Ca I CaI2 -1 I Ion net charge = zero!

  12. 2 Shared electrons 2 Shared electrons IV. Covalent Bonds • A. Nonmetal – Nonmetal • B. Electrons are shared • C.Molecules are produced • D. Sharing makes the bond (tug-o-war) • F F or F F

  13. Double:O O or O O Triple:N N or N N 4 Shared electrons 4 Shared electrons 6 Shared electrons 6 Shared electrons E. Can have double and triple bonds (a stronger bond) (the strongest bond)

  14. F. Diatomic elements are formed as follows: H2N2O2F2 Cl2Br2I2 BrINClHOF

  15. H H H C H H H H Let’s Practice! Before bonding After Bonding Chemical Formula CH4 C H All atoms are stable!

  16. Now you try some. 1. N and F 2. H and O 3. Diagram the molecule C2H6O

  17. F N F N F F F F F Answer to #1: before after formula NF3

  18. H H O O H H Answer to #2: before after formula H2O

  19. H H H H H H C C C C O O H H H H H H Answer to #3: C2H6O or

  20. V. Metallic Bonds • A. metal – metal • B. Electrons are pushed from atom to atom. • C. Electrons are free to move among the • metal atoms allowing metals to conduct • electricity. (see picture below) • D. A mixture of metals is • called an Alloy.

  21. VI. Ionic Binary Chemicals • A. Formula Writing • 1. Cation first, anion second • Ca+2Cl-1 • 2. Net charge must equal zero • Ca+2Cl-1 Cl-1= zero • (It takes 2 chloride ions to stabilize the Ca) • 3. Write the formula: CaCl2

  22. B. Naming • 1. The metal ion has the same name • as the metal atom. • Ca+2 is named calcium • K+1 is named potassium • 2.Some metals form more than one ion. • These metals require a roman numeral • after their name to indicate which ion is • in the chemical formula. • Fe+2 is named iron (II) • Fe+3 is named iron (III)

  23. NO roman numeral in the name, element only produces one common ion. Roman numeral is necessary, element contains more than one common ion.

  24. 3. The nonmetal ion will end with the • suffix -ide. • Examples: • S-2 is named sulfide • F-1 is named fluoride • O-2 is named oxide • P-3 is named phosphide • N-3 is named nitride

  25. VII. Ionic Ternary Chemicals • A. Formula Writing • 1. Follow the ionic rules. • 2. Ternary chemicals contain a • polyatomic ion. • polyatomic ion- a group of covalently • bonded atoms that act as a single ion • examples: CO3-2 NH4+1

  26. zero net charge Ca(NO3)2 YES, two NO3-1 ions! • 3. RULE: If more than one polyatomic ion is needed to write the chemical formula use parenthesis. • example:Ca+2 NO3-1 • NO3-1 • CaNO32 (looks like we have 32 oxygen atoms)

  27. B. Naming • 1. Follow the ionic rules. • 2.Examples: • Al(OH)3is named aluminum hydroxide • Cu(NO3)2is named copper (II) nitrate • K2CO3is named potassium carbonate

  28. VIII. Covalent Chemicals A. Greek prefixes are used to identify the number of each element in a covalent compound. mono = 1 di = 2 tri = 3 tetra = 4 penta = 5 hexa = 6 hepta = 7

  29. B. Rule: mono- is never used for the first element in the compound. C. Sometimes the last letter of the prefix is dropped if the name of the element starts with a vowel. D. Examples: CO2 is named carbon dioxide CO is named carbon monoxide dinitrogen monoxide is written as N2O

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