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Chemistry 400 Nomenclature

Chemistry 400 Nomenclature. Nomenclature. The term “nomenclature” refers to the system of names and terms used by chemists to name chemical compounds

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Chemistry 400 Nomenclature

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  1. Chemistry 400Nomenclature

  2. Nomenclature • The term “nomenclature” refers to the system of names and terms used by chemists to name chemical compounds • IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general developed and kept up to date by the International Union of Pure and Applied Chemistry (IUPAC).

  3. Nomenclature • You will learn to name the following: • simple ionic compounds (also called ionic salts or just salts); • simple covalent compounds containing 2 elements (also called binary covalent compounds); • simple acids (inorganic acids or mineral acids and 2 organic acids)

  4. Nomenclature • How do you tell by the formula whether a compound is ionic, covalent, or an acid? • Ionic compounds have a metal combined with a nonmetal, like NaCl • You can also have a metal combined with a polyatomic anion, like NaNO3 or Na2SO4 • You can also have the polyatomic cation, NH4+, combined with a nonmetal anion or a polyatomic anion, like NH4Cl or (NH4)3PO4

  5. Nomenclature • Covalent compounds typically have nonmetals bonded to other nonmetals (or metalloids), like SiCl4 • Inorganic (mineral) acids have H as the first element (except H2O), like HCl or HNO3 • Note that inorganic acids may or may not contain O (and it makes a difference in the name)

  6. Nomenclature • Organic acids can have the H at the beginning of the formula but more commonly it is written at the end, like CH3CO2H • You will only be expected to know acetic acid (above) and oxalic acid, C2H2O4

  7. Nomenclature Ionic Compounds

  8. Nomenclature How to Write Name from Ionic Formula You will learn how to write the name of an ionic compound from its formula ex.: AlPO4 is aluminum phosphate Procedure: 1. Cation is ALWAYS first in formula and in name! 2. Pick out the cation and the anion. a. The only polyatomic cation you will work with is NH4+ b. All other cations contain only 1 element c. So check, is the cation NH4+? If yes, then everything after NH4 is the anion. If no, then the cation is the FIRST element, everything after the first element is part of the anion.

  9. Nomenclature Practice finding the cation and the anion: i. AlPO4 ii. NH4Cl iii. Fe(NO3)2 iv. KH2PO4 v. NaMnO4 vi. CuCN

  10. Nomenclature 3. Once you have picked out the cation ask: Does the cation have a fixed charge? a. If yes, then name the cation with the element name and go on to the anion. b. If no, then name the cation with the element name and put ( ) after the name (leave space for charge). 4. Name the anion. 5. You are done if the cation had a fixed charge. 6. If the cation did not have a fixed charge you must now calculate the charge: a. Remember, the total cation charge + the total anion charge MUST equal zero. b. Using the fixed anion charge, figure out the total anion charge, and calculate the charge on the cation. c. This cation charge goes into the ( ) using roman numerals.

  11. Nomenclature How to Write Ionic Formula from Name You will learn how to write the ionic formula from the name ex: ammonium sulfide is (NH4)2S • All cation names are ONE WORD! So the FIRST word in the name is the cation.* Everything after the first word is the anion. Anion names may be more than one word. * There are some ionic salts with 2 cations, like NH4KSO4

  12. Nomenclature 2. Pick out the cation and anion. Practice: • Potassium bisulfate • ammonium dihydrogen phosphate • manganese(II) sulfide • lead(IV) hydrogen carbonate 3. Write the formula and charge for the cation and anion (this is an intermediate step, you are not done)

  13. Nomenclature • Use the criss-cross method to determine the final ionic formula. Example: aluminum sulfide 5. Use ( ) around polyatomic ions if you need more than One 6. Is the formula in the most reduced formula?

  14. Nomenclature Covalent Compounds

  15. Nomenclature How to Write Names and Formulas for Simple Nonionic Compounds Nonmetals may react with each other to form compounds. 1. How do you name simple nonmetal compounds? • Example: SiO2 • You always name the first element first using the element name. • Si is silicon 3. Name the second element as if it were an anion (-ide ending). O is oxide.

  16. Nomenclature 4. Use the prefixes in the table below (memorize them) to tell how many atoms of each element there are. • The prefix mono is never used for the first element. So silicon stays silicon, not monosilicon; and oxide becomes dioxide.

  17. Nomenclature • The final answer is silicon dioxide • There is also a hydrogen rule: • If it is a binary compound (or HCN) containing H like HF, then NO prefixes are use. So HF is hydrogen fluoride. This does not apply if they are in (aq) sln. 7. Final Rule: Drop the vowel at the end of mono, tetra, penta, hexa, hepta, octa, nona, and deca if it precedes oxide.

  18. Nomenclature You can also easily write a formula from its name! Example: dinitrogen pentoxide 1. What's the formula for nitrogen? N 2. How many atoms are there of nitrogen? di is 2, so N will be N2 3. What's the formula for oxide? O 4. How many atoms are there of oxygen. penta is 5, so O will be O5 5. Final answer is N2O5

  19. Nomenclature Acids

  20. Nomenclature Naming Acids Acids without Oxygen • Did you notice that we named the acid HF as hydrogen fluoride? • This is how we would name a binary acid (and HCN) if it were not dissolved in water. • In water, binary acids which contain NO oxygen get the prefix hydro- and the suffix -ide becomes -ic acid. • So although HCN(g) is hydrogen cyanide, HCN(aq) is hydrocyanic acid.

  21. Nomenclature Naming Acids Acids with Oxygen, or Oxyacids • Many acids contain oxygen, like H2SO4 • These acids only have one name, unlike the above binary acids without oxygen. • Look at the acid, like HClO4. • Remove the H, and what do you have? ClO4- • You have the polyatomic ion perchlorate.

  22. Nomenclature Naming Acids • Actually, all acids have 1 or more polyatomic ions which are made from the acid. • That's why acids are called "parent acids": the polyatomic ions are derived from them. • OK, back to HClO4: if its polyatomic ion is perchlorate, the rule is that an -ate suffix becomes an -ic acid. (The prefix remains unchanged). • Likewise, polyatomic ions with an -ite ending become -ous acids.

  23. Nomenclature Naming Acids • Remember that polyprotic acids like H3PO4 can lose more than 1 proton, so look for the polyatomic ion which has lost ALL of the protons possible. • PO43- for H3PO4, so phosphate becomes phosphoric acid. • Note that –ate anions have 1 more oxygen in their formula than the –ite anions. SO42- vs. SO32- & NO3- vs. NO2-

  24. Acid to Anion & Vice Versa

  25. Nomenclature Naming Acids • Name the following: HNO2, HBrO3, H2SO4 • What about the per- in perchlorate and the hypo- in hypochlorous acid? • Per- means more while hypo- means less; and they mean the oxygen atoms in the ion or acid.

  26. Nomenclature Naming Acids • The halogen oxyacids have a very regular pattern: • 4 oxygens is per- -ic acid per- -ate ion • 3 oxygens is -ic acid -ate ion • 2 oxygens is -ous acid -ite ion • 1 oxygen is hypo- -ous acid hypo- -ite ion periodic acid, HIO4 periodate ion, IO4- iodic acid, HIO3 iodate ion, IO3- iodous acid, HIO2 iodite ion, IO2- hypoiodous acid, HIO hypoiodite ion, IO-

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