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Bond types and charges

Bond types and charges. Naming compounds. Always follow flow chart for naming. Does the compound contain a metal?. NO. YES. No metal, then you use prefixes: Mono, Di, Tri, Tetra, Penta , . Is that metal a transition metal?. NO. YES. Use Roman Numerals to show the charge.

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Bond types and charges

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  1. Bond types and charges

  2. Naming compounds • Always follow flow chart for naming Does the compound contain a metal? NO YES No metal, then you use prefixes: Mono, Di, Tri, Tetra, Penta, Is that metal a transition metal? NO YES Use Roman Numerals to show the charge Then NO prefixes or Roman Numerals

  3. Compounds without a metal Most compounds without a metal have some form of covalent bond. No metal means that we use prefixes to name the compounds A. The prefix goes before the element B. The prefix used must equal the subscript on that element C. If the first element has a subscript of one you do not put “mono” D.Always change the last element to the ending “ide”

  4. Example What would be the formula of dinitrogen trioxide? Di nitrogen tri oxide N O 2 3

  5. Example What is the formula of tetranitrogentriiodide? N I 4 3

  6. Examples P3F5 C4O2 H2O NF3 Si2Br5 • Triphoporuspentaflouride • Tetra Carbon dioxide • Dihydrogen Monoxide • Nitrogen triflouride • Disiliconpentabromide

  7. Lets go the other way What is the name of H3P2? Last chemical name always ends in “ide” 3 2 hydrogen phosphorus Tri phosphide di Then put the prefix that corresponds to the subscribe

  8. Another Name P2F4 What is the name of the compound C H4? Diphosphporus tetra flouride Carbon Monocarbontetrahydride If first element has a subscribe of 1, You don’t write “mono”

  9. More practice Write the names of: • N2O4 • P3Cl3 • CO2 • B2Cl5 Dinitrogentetraoxide TriPhosphoroustrichloride Carbon Dioxide DiboronPentachloride

  10. Bond types and charges

  11. Group 1 and 2 metals The elements of a group will all have identical Lewis structures They form ionic bonds so alkali metals will always give away one electron If the metal loses one electron? What will be its charge? +1e- +1e- +1e- Alkali metals (group 0ne) will ALWAYS have a +1 charge, no matter what it is bonded to

  12. Alkaline Earth Metals. All have two valence electrons Be Mg Ca Sr Ba Be+2 + 2e -1 Mg+2 + 2e -1 Ca+2 + 2e -1 Sr+2 + 2e -1 Ba+2 + 2e -1 The Alkaline earth metals are always a +2 because they lose both electrons

  13. Recap Group one elements form a cation with a +1 charge. Group 2 elements form a cation with a +2 charge.

  14. What about anions? The halogens (group 17) will always have 7 valence electrons So they want to gain one more electron -1 -1 -1 -1 + 1e-1 = + 1e-1 = + 1e-1 = + 1e-1 = So all The halogens have a -1 charge

  15. What about group 16? Group 16 all have 6 valence electrons. They want to pick up two more electrons. -2 + 2 e-1 = So group 16 elements will always have a charge of -2

  16. Recap Group 1 +1 Group 2 +2 Group 15 -3 Group 16 -2 Group 17 -1

  17. Compounds with metals Compounds with metals always combine a cation with an anion. The overall charge of the compound must be equal to zero. The cation is ALWAYS written first Metals in group one and two are named with no prefixes or roman numerals

  18. Example What is name of MgCl2 ? Mg is a metal but not a transition metal. So we just name it. Magnesium Chloride Magnesium is a group 2 metal so it has a charge of +2. That makes it the cation and the cation is always written first. If the anion is a single element, we change its name to end in “ide”. Just like before.

  19. Example Name NaBr. Sodium is a group 1 metal so… 1. It has a charge of +1 2. It is the cation 3. It is not a transition metal so we just name it Sodium Bromide

  20. Work these Calcium Oxide Lithium flouride Potassium Sulfide Beryllium Chloride Nitrogen Dioxide • CaO • LiF • K2S • BeCl2 • NO2

  21. Bond types and charges

  22. Review so far Write the names of the following • BeF2 • K2O • Ba3N2 • LiCl • Na3P Beryllium Flouride Potassium Oxide Barium Nitride Lithium Chloride Sodium Phosphide

  23. Again What are the names of the following • Ca F2 • CF4 • KBr • N3O2 • CS2 • CaS • HI Calcium flouride Carbon tetraflouride Potassium Bromide Trinitrogen Dioxide Carbon disulfide Calcium Sulfide Hydrogen mono-iodide

  24. Going the other way When writing compounds with metals, you must make sure they are charge balanced Charge balanced means that the overall compound has a neutral charge

  25. Example • Write the formula for Lithium Iodide 1. You must charge balance them. So write the charges +1 -1 Li I Check the math: 1 lithium atom with a positive 1 charge: 1 x (+1) = 1 1 Iodine atom with a negaitve 1 charge: 1 x (-1) = -1 Add them together: 1 + (-1) = 0. It is charged balanced

  26. Example What is the formula of Magnesium Chloride? +2 -1 Mg Cl Mg Cl2 We need another negative one to be charge balanced 2 Write the charges of each. Magnesium - 1 x (+2) = +2 Chlorine - 1 x (-1) = -1 2 x (-1) = -2 2 + (-2) = 0 Not Charge (+2) - (1) = +1 Balanced

  27. Another way Lets look at magnesium chloride. We Know it is MgCl2 -1 +2 Write the charges Mg Cl If the subscripts do not reduce, Cross them and drop them down 2 Then drop the + or - signals

  28. The Cross Method The cross method works but you have to be careful to reduce the charges before you drop them down. What is the formula for Calcium oxide? +2 -2 Ca O CaO 2 2 This is incorrect. If a compound with a metal can be reduced it needs to be reduced.

  29. Practice Write the Formulas for • Sodium Flouride • Potassium Oxide • Calcium Sulfide • Magnessium Nitride • Nitrogen Dioxide NaF K2O CaS Mg3N2 NO2

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