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Chapter 9

Chapter 9. Chemical Names and Formulas. Copper Compounds. What is the difference between Cu 2 O and CuO ? Is there any difference?

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Chapter 9

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  1. Chapter 9 Chemical Names and Formulas

  2. Copper Compounds • What is the difference between Cu2O and CuO? Is there any difference? • You may think that there is very little difference between the two, but there is! Naming compounds very specifically is important in order to tell the difference between similar compounds? • Cu2O • Red powder • fungicide • CuO • Black powder • Used in batteries

  3. Remeber Naming Ions? • What is a cation? • Cations – positively charged ion • How many electrons does Group 1,2, and 3 lose? • Groups 1,2, and 3 lose electrons • Group 1 – lose 1 electron • Group 2 – lose 2 electrons • Group 3 – lose 3 electrons

  4. Remember Naming Ions? • Anion – negatively charged ion • Groups 5,6, and 7 generally gain electrons • Group 5 – gain 3 electrons • Group 6 – gain 2 electrons • Group 7 – gain 1 electron

  5. Naming Ions Transition metals usually lose electrons, how many electrons they lose depends on the element

  6. Naming Ions • If you actually think about it, it will make sense why some of the transition elements could have two different ions • Ex: Copper (Cu) forms both a +1 and a +2 cation • Why? (Hint: Use the periodic table and electron configuration.) • +1 cation: Cu = [Ar] 4s1 3d10 – loses 1 from the 4s subshell • +2 cation: if Cu does not achieve pseudo-stability, it is [Ar] 4s2 3d9 – will lose the two electrons from the 4s subshell

  7. Polyatomic Ions Ions composed of more than 1 atom You just have to memorize these Most end in –ite or –ate -ite tells you there is 1 less oxygen atom than the –ate ending

  8. Naming and Writing Formulas for Ionic Compounds • what do ionic compounds contain? • Ionic compounds – contain a metal and a nonmetal • How do we name a binary ionic compound (binary means composed of 2 elements)? • Place the cation name first, then the anion name • Usually add –ide to the end of the anion name

  9. Naming and Writing Formulas for Ionic Compounds • What would Cs2O be? • Cesium oxide • NaF? • Sodium fluoride • Cu2O (hint: copper has two possible ions! Which one is it?) • Copper (I) oxide • SnS2 • Tin (IV) Sulfide • Mn2O3 • Manganese (III) oxide • LiCN • Lithium cyanide • (NH4)2C2O4 • Ammonium oxalate (the –ide ending is usually left out if the anion is a polyatomic ion)

  10. Naming and Writing Formulas for Ionic Compounds • To write a formula for a binary ionic compound, we need to go back to Ch. 7 and balance the charges • Ex: iron (III) oxide • Fe+3 O-2 • Fe2O3 • Ca+2 S-2 • Ca2S2….reduce to CaS • Remember crisscross the charge and reduce subscripts to the lowest whole number ratio

  11. Naming and Writing Formulas for Ionic Compounds • Another way…just think about how you would balance the charges out by finding the least common multiple • K+1 N-3 • We need a 3 to balance out the +1 on K (1 x 3 =3) and a 1 to balance out the -3 on N (1 x 3) = 3 • So K3N • Ba+2 S-2 • Both have a 2 charge, they balance each other out • BaS

  12. Naming and Writing Formulas for Ionic Compounds • For polyatomic ions, keep the ion together – balance the overall charge of the ion • Ex: Ca+2 (NO3)-1 • Ca(NO3)2 • Use parentheses to set off the polyatomic ion only if there is than one of the polyatomic ion • Ex: Li+1 (CO3)-2 • Li2CO3 – no parentheses because there is only one polyatomic ion • Ex: NH4+1 (SO3)-2 • (NH4)2SO3

  13. Naming and Writing Formulas for Molecular Compounds • What is a binary molecular compound? • A compound composed of 2 elements that are both nonmetals – NOT ions • Binary compounds can have 2 elements composed in various ways – ex: CO and CO2 or NO and N2O so we can’t name them like we did with ionic compounds • We need prefixes…prefixes tell us how many atoms of each element are present in each molecule

  14. Naming and Writing Formulas for Molecular Compounds • Here are a few hints: • If there is only 1 atom of the first element, omit the prefix mono- • You will usually add the –ide ending to the second element • Ex: CO • Carbon monoxide • Ex: N2O • Dinitrogen monoxide • Ex: Cl2O7 • Dichlorineheptoxide • Ex: BCl3 • Boron trichloride

  15. Naming and Writing Formulas for Molecular Compounds • Use the prefixes of each element to write the formula (hint: -mono is left out of the first element if there is only 1 atom) • Ex: carbon monoxide • CO • Ex: carbon tetrabromide • CBr4 • Ex: diphosphorus trioxide • P2O3 • Ex: iodine heptafluoride • IF7

  16. Summarization

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