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Naming Compounds and Writing Formulas

Naming Compounds and Writing Formulas. Chapter 7. Ban DHMO?. DHMO is dihydrogen monoxide. Evaluate the following link and decide if this potentially dangerous chemical should be prohibited. www.dhmo.org. 5 types of chemical compounds Binary ionic - metal ion – nonmetal ion

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Naming Compounds and Writing Formulas

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  1. Naming Compounds and Writing Formulas Chapter 7

  2. Ban DHMO? • DHMO is dihydrogen monoxide. • Evaluate the following link and decide if this potentially dangerous chemical should be prohibited. • www.dhmo.org

  3. 5 types of chemical compounds • Binary ionic - metal ion – nonmetal ion • Ternary ionic - at least one ion is a polyatomic ion • Binary molecular - two nonmetals • Binary acid - H – nonmetal • Ternary acid - H – Polyatomic ion

  4. Tips to keep in mind when naming and writing formulas: Always keep your Periodic Table handy – You should have it in front of you ALWAYS when you are naming and writing formulas. Remember that metals (except Hydrogen) are found to the left of the stairstep on the Periodic Table. Nonmetals are found on the right side of the Periodic Table. Transition Metals are found from Group 3 to the stairstep (except aluminum which is a regular metal)

  5. How do you name binary ionic compounds? (composed of two elements – a metal and a nonmetal) • Name the first ion • If the first ion is a transition element other than zinc, cadmium, or silver, you must use a Roman Numeral with the name – we’ll discuss this later. • Name the second ion changing the suffix to –ide.

  6. Examples NaCl What is the name of this compound: HIJKLMNO? WATER – “H” to “O” You have to admit – that was funny! Name the metal ion Sodium Chloride CaO Name the nonmetal ion, changing the suffix to –ide. Oxide Calcium Al2S3 Aluminum Sulfide MgI2 Magnesium Iodide This is two metals – not a binary ionic compound BaNa2 The name of this is Banana (JOKE – haha) You should recognize a problem with this one

  7. What about the transition metals and using roman numerals? How does that work? Let’s see. FeO Notice – metal and nonmetal. Name the first ion. Since the first ion is a transition element, you must use a Roman Numeral to represent the charge. Iron II Oxide How do you know the charge? Deductive reasoning. All compounds are neutral. Oxygen has a -2 charge (group 16) Therefore ….. Iron must have a +2 charge since there is one iron and one oxygen. Iron gets a Roman Numeral II. Isn’t this easy and FUN!!!

  8. Cu2S Name the first ion. Since it is a transition metal, you must use a Roman Numeral. Which Roman Numeral? The Roman Numeral is the same as the charge of the ion. How do you find the charge? Deductive reasoning! All compounds are neutral Sulfur has a -2 charge (group 16) There are two coppers. Therefore each copper must have a +1 charge for all ions to be neutral Copper I Sulfide

  9. Another Example: MnO2 Name the first ion. Since it is a transition metal, you must use a Roman Numeral. How do you determine the Roman Numeral? It is the same as the charge. What is the charge of Mn? All compounds are neutral. Oxygen (group 16) has a -2 charge. There are two oxygens and one Mn. Therefore Mn must have a +4 charge for this compound to be neutral. Manganese IV oxide

  10. So why must we use Roman Numerals with transition elements? The metals in groups 1, 2, and 13 have single, definite charges. Group 1 metals have a +1 charge. Group 2 metals have a +2 charge. Group 13 metals have a +3 charge. Transition metals may have multiple charges – usually two different positive charges. For example, there are two copper oxide compounds: CuO Copper II oxide Copper is +2 Cu2O and CuO Cu2O Copper I oxide Copper is +1 We can’t just say Copper oxide. Which one of these is Copper oxide? We must distinguish these by using a Roman Numeral

  11. There are three transition elements which do not require a Roman Numeral because they have single definite charges. These are Zinc – Zn+2 Cadmium – Cd+2 Silver – Ag+1 You need to remember the charges for these. No Roman Numerals needed for these. Ag2O Name the first ion. Name the second ion changing the suffix to –ide. oxide Silver ZnCl2 Name the first ion. Zinc chloride Name the second ion changing the suffix to –ide.

  12. Sometimes you will see the transition elements named using common names. Transition metals named with Roman Numerals involves stock names. The common names use the Latin derivative of the element’s name with a suffix of either –ous or –ic. The –ous suffix name corresponds with the smaller charge. The –ic suffix name corresponds with the larger charge. Cuprous = Copper I Cupric = Copper II Ferrous = Iron II Ferric = Iron III There are many more – just be familiar with these six common names. Plumbous = Lead II Plumbic = Lead IV

  13. In Summary

  14. How do you write formulas for binary ionic compounds given the name? • Two simple steps: • Write the symbol and charge of each ion • Balance the charges by providing subscripts Magnesium chloride Write the symbol and charge of each ion. Mg+2 Cl-1 Balance the charges by supplying subscripts. Subscripts tell how many of each atom is present. Cl-1 MgCl2 You need a second Cl-1 to balance the charges

  15. More examples: Iron III bromide Write the symbol and charge of each ion. The charge of the iron is provided by the Roman Numeral. Fe+3 Br -1 Br -1 Br -1 FeBr3 Balance the charges by supplying subscripts. The subscripts tell how many of each ion is needed to balance the compound. You’ll need three bromine ions to balance the one iron.

  16. Aluminum Sulfide Write the symbol and charge of each ion. Al+3 S-2 S-2 Al+3 Balance the charges by supplying subscripts. S-2 In this case the charges do not evenly divide into each other. You must find the least common multiple. SIX Al2S3 How many aluminums are needed to arrive at a +6 charge? 2 How many sulfurs are needed to arrive at a -6 charge? 3

  17. Second Category of compounds – Ternary Ionic Compounds. These compounds contain at least one polyatomic ion. What is a polyatomic ion? Let’s look at the name to try to understands. It is an ion – that means it has a charge. It is polyatomic – that means it is made of more than one atom. Simple as that!! Let’s look at some examples of polyatomic ions.

  18. CO3-2 carbonate This ion is composed of one carbon and three oxygens and the entire group has a charge of -2. Polyatomic ion – Group of atoms that act as a unit and carry a charge. More examples: PO4-3 Phosphate C2H3O2-1 Acetate SO4-2 Sulfate OH-1 Hydroxide SO3-2 Sulfite NO3-1 Nitrate ClO4-1 Perchlorate NO2-1 Nitrite ClO3-1 Chlorate NH4+1 Ammonium (only positive PI) ClO2-1 Chlorite ClO-1 Hypochlorite You need to learn these!!!

  19. How do you recognize Ternary Ionic Compounds? • Composed of two ions in which at least one is a polyatomic ion. • There is only one positive polyatomic ion (NH4+1) • Three possible types of Ternary Ionic Compounds: • Ammonium + negative ion (nonmetal) • Metal (positive ion) + negative polyatomic ion • Ammonium + negative polyatomic ion s Polyatomic Ion

  20. How do you name Ternary Ionic Compounds? EASY! PIECE OF CAKE! NO PROBLEM! Name the first ion. Name the second ion. Isn’t that simple??!! Examples: When you look at this compound you should recognize that this is NOT binary. There are THREE elements present. When you see this, immediately look for a polyatomic ion. Carbonate is present here. Na2CO3 Sodium carbonate Notice that you do NOT change the suffix – just name the polyatomic ion Name the first ion. Name the second ion.

  21. A few more examples: Fe(OH)3 Name the first ion. Iron hydroxide Remember that iron requires a Roman Numeral since it is a transition element. What Roman Numeral should be used? III Since there are 3 OH groups, each with a -1 charge, the charge of the iron must be +3 for the compound to be neutral • The Roman Numeral comes from the charge of the ion. How do you find the charge of the iron? • You know two things: • All compounds are neutral. • You know the charge of OH (-1) Name the polyatomic ion.

  22. NH4Cl Name the first ion. Ammonium Name the second ion. chloride Notice that since the second ion is a nonmetal that, like binary ionic compounds, the suffix of the nonmetal changes to –ide. Name the first ion. (NH4)3PO4 Ammonium phosphate Name the second ion. Looks like a monster, but it’s really a pussycat.

  23. ONE more example: Cu2SO4 Name the first ion. You should realize that you need a Roman Numeral since copper is a transition metal. sulfate Copper I The Roman Numeral is the same as the charge. What is the charge? The charge of sulfate is -2. Since there are two coppers, the charge of the copper must be +1. Name the second ion.

  24. How do you write formulas for Ternary Ionic Compounds? • Very much like writing formulas for Binary Ionic Compounds. • Two steps: • Write the formulas/symbols of each ion. • Balance the charges by supplying subscripts. • If a subscript is needed for a polyatomic ion, it must be put in parentheses with the subscript on the outside. • Let’s do some!!

  25. Aluminum nitrate First, you can tell from the name that there is a polyatomic ion present (nitrate). All binary ionic compounds have suffixes of –ide. Al+3 NO3-1 Al(NO3)3 Write the formula/symbol and charge of each ion. Balance the charges by supplying subscripts. Since Al is +3 and NO3 is -1, you need a total of 3NO3-1 to balance one Al+3 Since you will need a subscript of 3 for NO3-1, you need to put this in parentheses with the 3 outside.

  26. Lead (IV) acetate Write the formula/symbol and charge of each ion. Pb+4 C2H3O2-1 Balance the charges by supplying subscripts. Since Pb is +4 and C2H3O2 is -1, you will need 4 C2H3O2-1 to balance 1Pb+4 Pb(C2H3O2)4 Write the formula/symbol and charge of each ion. Calcium phosphate Ca+2 PO4-3 Balance the charges by supplying subscripts. Since Ca is +2 and PO4 is -3, you will need 3 Ca+2 to balance 2 PO4-3 Ca3(PO4)2

  27. The Third Category of Compounds – Binary Molecular What are Binary Molecular Compounds? These compounds contain two elements (binary). The term “molecular” indicates that these elements are joined by a covalent bond. They must therefore be nonmetals. Bottom line – 2 elements – both nonmetals To name and write formulas for these, you must know some numerical prefixes.

  28. Naming – you must use prefixes. • 1 = mono 3 = tri 5 = penta 7 = hepta 9 = nona • 2 = di 4 = tetra 6 = hexa 8 = octa 10 = deca • Steps • The first nonmetal only gets a numeric prefix when there is more than one. No prefix if there is only one. • The second element always gets a numeric prefix and always has a suffix of -ide

  29. CO2 Carbon dioxide CO Carbon monoxide N2O4 Dinitrogen tetraoxide H2O Dihydrogen monoxide CCl4 Carbon tetrachloride Name the first element. Since there is only one, no prefix is needed. The second element always gets a prefix and a suffix of –ide. Name the first element. Since there are two present, the prefix “di” is needed. The second element always gets a prefix and a suffix of –ide. Do you think it wise to BAN DHMO?

  30. AlCl3 What do you think about this one??? Be careful. This is a metal and nonmetal. Always keep your Periodic Table in front of you for reference. You may have been tempted to say “aluminum trichloride”. This is INCORRECT! This is a binary IONIC compound. No prefixes are used. Simply aluminum chloride. Given the names of binary molecular compounds, how do you write the formulas? Very easy to do!!! The prefixes tell you how to write the formulas. DO NOT CONSIDER CHARGES. NONMETALS ARE ALL NEGATIVE SO TO USE CHARGES DOES NOT WORK!

  31. Silicon dioxide Silicon and oxygen are both nonmetals. The lack of a prefix on silicon means that there is only ONE silicon. The prefix “di” in front of oxide means that there are TWO oxygens. SiO2 Diphosphorous pentachloride P2Cl5 Phosphorous and chloride are both nonmetals. The prefix “di” means that there are TWO phosphorouses (Is that a word?) The prefix “penta” before chlorine means that there are five chlorines.

  32. Nitrogen monoxide Nitrogen and oxygen are both nonmetals. The lack of a prefix on nitrogen means only ONE nitrogen. The prefix “mono” on oxygen indicates ONE oxygen. NO Is this not sooooooo easy!??

  33. What are Binary Acids? Binary means two elements Acid means it contains hydrogen The second element is a nonmetal hydrogen – nonmetal Naming All binary acids follow the pattern as shown below:

  34. Stem or root of nonmetal Prefix Suffix Acid -ic Hydro- < NM > HCl is a binary acid – hydrogen - nonmetal HCl Acid Hydro chlor ic Hydro iod ic Acid HI Hydro sulfur ic Acid H2S

  35. Given the name, how do you write formulas for binary acids? The obvious pattern of the name tells you that it is a binary acid. Hydro<NM>ic Acid. Therefore, you know that the acids begins with hydrogen and contains a nonmetal which you can identify between the “Hydro” and the “ic” To arrive at the formula, you “pretend” that hydrogen is +1 and using the normal charge of the nonmetal, balance the formula by supplying subscripts. Hydrofluoric Acid The name tells you that this is a binary acid. H+1 F-1 HF

  36. Hydrophosphoric acid The name tells you that it is definitely a binary acid. H+1 P-3 H3P Remember that the P has a -3 charge because it is in group 15

  37. Let’s Practice Ca(OH)2 Calcium hydroxide SO2 Sulfur dioxide (NH4)3PO4 Ammonium phosphate Co2(CO3)3 Cobalt (III) carbonate HBr Hydrobromic acid Ternary Ionic Binary molecular Ternary Ionic Ternary Ionic Binary acid

  38. Potassium acetate KC2H3O2 Cadmium nitrate Cd(NO3)2 Aluminum oxide Al2O3 Hydrosulfuric acid H2S Difluorine trioxide F2O3 Ternary Ionic Ternary Ionic Binary Ionic Binary acid Binary molecular

  39. The fifth category of compounds is Ternary Acids. These compounds begin with hydrogen since they are “acids”. Attached to the hydrogen is a polyatomic ion Hydrogen – polyatomic ion

  40. How are Ternary Acids named? There are two categories of naming depending on the suffix of the polyatomic ion. First Category: If the polyatomic ion has a suffix of –ate or –ide, use the following pattern: suffix -ic acid <Root of polyatomic ion> Ternary Acid – contains the polyatomic ion nitrate (suffix –ate). Ternary Acid – contains the polyatomic ion cyanide (suffix –ide). Ternary Acid – contains the polyatomic ion sulfate (suffix –ate). Ternary Acid – contains the polyatomic ion chlorate (suffix –ate) ic HClO3 Chlor Acid ic Nitr Acid HNO3 ic Sulfur Acid H2SO4 ic HCN Cyan Acid

  41. Second Category:If the polyatomic ion has a suffix of –ite, use the following pattern: suffix -ous acid <Root of polyatomic ion> Ternary acid contains polyatomic ion, nitrite (-ite suffix). HNO2 acid Nitr ous Chlor ous acid Ternary acid contains polyatomic ion, chlorite (-ite suffix). HClO2 Ternary acid contains polyatomic ion, sulfite (-ite suffix). Sulfur ous acid H2SO3

  42. How are Ternary Acids named? First, a ternary acid is easy to distinguish from a binary acid. ALL binary acids have the prefix “hydro-”. NO Ternary acids have the prefix “hydro-”. Acetic acid This is an acid, but NOT a binary acid. This is a ternary acid. The “-ic” suffix in the acid name tells you that the polyatomic ion must have a “-ate” suffix – acetate. To write the formula, pretend that hydrogen is +1 and balance the charges. H+1 C2H3O2-1 HC2H3O2

  43. Hypochlorous acid This is a Ternary acid (does not begin with “hydro-”. H+1 ClO-1 The “-ous” suffix indicates that the polyatomic ion in this acid has a suffix of “-ite” - hypochlorite HClO Pretend that hydrogen is +1 and balance the charges. This is a Ternary acid (does not begin with “hydro-”. Phosphoric acid H3PO4 The “-ic” suffix indicates that the polyatomic ion in this acid has a suffix of “-ate” - phosphate Pretend that hydrogen is +1 and balance the charges.

  44. This concludes Module 13!

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