1 Essential Knowledge AP Chemistry Week 1 and 2 Before we even start the assigned AP Chemistry curriculum you MUST know how to name compounds. We went through most of this last year but it needs to become a second hand notion quickly. YOU MUST MEMORIZE THE POLYATOMIC IONS ON PAGE 2! TEST FRIDAY 9/12. START TODAY! Objective: Identify, name, and write the formulas for A) Covalent Compounds B) Monatomic Ion, Binary Ionic Compounds C) Polyatomic Ionic Compounds D) Acids and Bases Schedule: Week 1 (09/02-09/05) - Tuesday 09/02/14: Student presented with essential knowledge packet - Wednesday 09/03/14: Review of covalent and monatomic ionic bonds - Thursday 09/04/14: Naming and writing Polyatomic Ions - Friday 09/05/14: Naming and writing acids and bases Schedule: Week 2 (09/08-09/12) - Monday 09/08/14: Review; Poster - Tuesday 09/09/14: Review Poster - Wednesday 09/10/14: Test 1 on naming covalent bonds and naming ionic bond; naming polyatomic ions, and acids/bases - You will be given polyatomic ion sheet seen on page 2 - Thursday: Syllabus, introduction to Chapter 1 of Zumdahl - Friday 09/12/14: Test on naming polyatomic ions (memorize page 2) 2 Poly = More than one or multiple, ion = charged particle Name ammonium Symbol NH4+ acetate C2H3O2- Bromate BrO3- Perchlorate ClO4- Chlorate ClO3- Chlorite ClO2- Hypochlorite ClO- Cyanide CN- Dihydrogen phosphate H2PO4- Hydrogen carbonate (bicarbonate) HCO3- Hydrogen sulfate (bisulfate) HSO4- Hydrogen sulfite (bisulfite) HSO3- Hydroxide OH- Iodate IO3- Nitrate NO3- Nitrite NO2- Permanganate MnO4- Thiocyanate SCN- Carbonate CO32- Dichromate Cr2O72- Chromate CrO42- Oxalate C2O42- Selenate SeO42- Silicate SiO32- Sulfate SO42- Sulfite SO32- Peroxide O22- Phosphate PO43- Phosphite PO33- 3 A) Covalent Compounds A1: What is a covalent compound? A covalent compound is a compound in which the atoms that are bonded share electrons rather than transfer electrons from one to the other. While ionic compounds are usually formed when metals or a metal and a metalloid bond to nonmetals, covalent compounds are formed when two nonmetals bond to each other. Rules in naming Covalent Compounds A2: Common Covalent Compound Some common covalent compounds have common names. These compounds do not follow the rules found below. We will be discussing many of these but there are some you should know that I have listed below. Compound H2O CH4 NH3 O3 Name Water Methane Ammonia Ozone A3: Diatomic Covalent Compounds Diatomic molecules (dia meaning two) are molecules that bind together. They are common and not found alone in nature. Since these molecules NEVER are alone so their name is their name on the periodic table. They include all gasses other than the Nobel gasses. Compound H2 N2 O2 F2 Cl2 I2 Br2 Name Hydrogen Nitrogen Oxygen Fluorine Chlorine Iodine Bromine 4 A4: Naming Rest of Binary (2 total) Covalent Compounds The rest of the covalent compounds require prefixes as seen below. You need to memorize these prefixes if you already don’t know them. Prefixes are necessary when naming covalent compounds because the atoms can combine in any whole number ratio. N2O, for example, cannot simply be called “nitrogen oxide,” because there are several other compounds that contain nitrogen and oxygen. We must specify that there are two nitrogen atoms bonded to a single oxygen atom. Rules 1. The first element is named first, using the elements name. 2. Second element is named as an Anion (suffix "-ide") 3. Prefixes are used to denote the number of atoms 4. "Mono" is not used to name the first element Note: when the addition of the Greek prefix places two vowels adjacent to one another, the "a" (or the "o") at the end of the Greek prefix is usually dropped; e.g., "nonaoxide" would be written as "nonoxide", and "monooxide" would be written as "monoxide". The "i" at the end of the prefixes "di-" and "tri-" are never dropped. Prefix monoditritetrapentahexaheptaoctanonadeca- You also need to know which element to put first in the formulas and names of these compounds. Generally, they are in the same left-to-right order that they have on the periodic table, except that you would have to squeeze hydrogen in between nitrogen and oxygen. Examples: Compound Name NO* N2O NO2* N2O3 N2O4 N2O5 Nitrogen Monoxide Dinitrogen Monoxide Nitrogen Dioxide Dinitrogen Trioxide Dinitrogen Tetraoxide Dinitrogen Pentaoxide * Notice that the prefix “mono” is omitted in these cases number indicated 1 2 3 4 5 6 7 8 9 10 5 A: Covalent Compound Practice Write the formulas for the following covalent compounds: 1) antimony tribromide __________________________________ 2) hexaboron silicide __________________________________ 3) chlorine dioxide __________________________________ 4) hydrogen iodide __________________________________ 5) methane __________________________________ 6) oxygen __________________________________ 7) iodine pentafluoride __________________________________ 8) bromine __________________________________ 9) dinitrogen trioxide __________________________________ 10) ammonia __________________________________ 11) phosphorus triiodide __________________________________ 12) nitrogen __________________________________ 13) water __________________________________ 14) ozone __________________________________ 15) dinitrogen monoxide __________________________________ Write the names for the following covalent compounds: 16) P4S5__________________________________ 17) O2 __________________________________ 18) SeF6 __________________________________ 19) Si2Br6 __________________________________ 20) SCl4 __________________________________ 21) CH4 __________________________________ 6 22) B2Si __________________________________ 23) NF3 __________________________________ 24) O3 __________________________________ 25) Cl2 __________________________________ 26) NH3 __________________________________ 27) H2 __________________________________ 28) CO __________________________________ 29) CO2 __________________________________ 30) NO2 __________________________________ Name of Covalent Compound Formula of Covalent Compound carbon dioxide phosphorus triiodide sulfur dichloride nitrogen trifluoride dioxygen difluoride N2F4 SCl4 ClF3 SiO2 P4O10 7 B) Monatomic ions, Diatomic ionic compounds B1: What is an ionic compound? An ionic compound is a compound in which transfer from one atom to the other. Ionic compounds are usually formed when metals bond to nonmetals. After this transfer of electrons, the atom that loses electrons becomes positively charged and is referred to as a cation and the atom that gains the electrons becomes negatively charged and is referred to as an anion. B2: Naming Monatomic Ions In order to determine the charge of monatomic ions, you can use the periodic table as a guide: Group # Ion Charge Examples (Column) 1 These elements lose one electron to form +1 ions. Na+, Li+, K+ 2 These elements lose two electrons to form +2 ions. Mg2+, Ca2+, Ba2+ The elements in groups 3-12 are called transition metals. These elements always lose electrons to form positive ions (cations) but their charges vary. Fe2+, Fe3+ Groups 312 For example, iron can form a +2 or a +3 ion. In cases like these, you must be told which ion to use. 13 These elements lose three electrons to form +3 ion. Al3+ 14 The charges on these ions vary. Carbon and silicon do not form ions. For the rest of the group, you must be given the charge. Sn2+, Pb2+ 15 These elements gain three electrons and form –3 ions. N3-, P3- 16 These elements gain two electrons to form –2 ions. O2-, S2- 17 These elements gain one electron to form –1 ions. F-, Cl-, Br-, I- These atoms do NOT form ions. Their charge is 18 He, Ne, Ar, Kr always zero. 8 Naming Ions (Nomenclature): Simple cations are named by saying the element and adding the word “ion.” Na+ is called “sodium ion” Mg2+ is called “magnesium ion” Simple anions are named by dropping the ending off the element name and adding “ide.” F- is called “fluoride” O2- is called “oxide” N3- is called “nitride” Note: the charge of a monatomic anion is equal to the group number minus 18 B2 Practice: name the following ions 1) F ________________________________ 2) Ca2+ ________________________________ 3) Pb4+________________________________ 4) I ________________________________ 5) Al3+________________________________ 6) Cd2+________________________________ 7) Fe3+________________________________ Write the formula for each of the following ions: 8) sulfide ion ________________________________ 9) thallium (III) ion ________________________________ 10) sodium ion ________________________________ 11) cobalt (II) ion ________________________________ 12) barium ion ________________________________ 13) bromide ion ________________________________ 14) iodide ion _______________________________ 9 B3: Naming Binary Ionic Compounds Ionic compounds are compounds formed by the combination of a cation and a anion. (Think: “metal plus nonmetal”). Ionic compounds are more commonly known as “salts.” Binary ionic compounds are compounds containing only two elements, as demonstrated in the examples below. When writing formulas for ionic compounds, we use subscripts to indicate how many of each atom is contained in the compound. Remember that even though ions have charges, ionic compounds must be neutral. Therefore, the charges on the cation and the anion must cancel each other out. In other words, the net charge of an ionic compound equals zero. Example 1: For a salt containing sodium ion, Na+, and chloride, Cl-, the ratio is one to one. The positive charge on the sodium ion cancels out the negative charge on the chloride. (+1) + (-1) = 0 Therefore, the formula for the salt is NaCl. (The actual formula is Na1Cl1, but chemists omit subscripts of 1). Example 2: For a salt containing calcium ion, Ca2+, and chloride, Cl-, the ratio can’t be one to one. (+2) + (-1) = +1 Remember that ionic compounds must be neutral. In order to yield a neutral compound, two chlorides must bond to the calcium ion: (+2) + 2(-1) = 0 So, the formula for this salt is CaCl2. Nomenclature: When naming ionic compounds, simply write the element name of the metal followed by the ion name of the nonmetal. (Remember: the metal ion (cation) is always written first!) NaCl is called “sodium chloride,” and CaCl2 is called “calcium chloride.” 10 B3 Practice: Name the following binary compounds Name of Ionic Compound Formula of Ionic Compound 1. Sodium bromide 2. Calcium chloride 3. Magnesium sulfide 4. Aluminum oxide 5. Lithium phosphide 6. Cesium nitride 7. Potassium iodide 8. Barium fluoride 9. Rubidium nitride 10. Barium oxide 11. K2O 12. MgI2 13. AlCl3 14. CaBr2 15. Na3N 16. LiF 17. Ba3P2 11 B4: Ionic Compounds Containing Transition Metals The transition metals are the elements located in the middle of the periodic table (in groups 312. Unlike the group 1A and 2A metal ions, the charges of transition metal ions are not easily determined by their location on the periodic table. Many of them have more than one charge (also known as an oxidation state). There are eight transition metals that you should highlight on your periodic table: Co, Cr, Cu, Fe, Mn, Hg, Sn, and Pb Each of these elements form more than one ion and therefore must be labeled accordingly. For example, iron forms two ions: Fe2+ and Fe3+. We call these ions “iron (II) ion” and “iron (III) ion” respectively. (See “Table of Transition Metal Ions”). When naming any ion from the elements listed above, you MUST include a Roman numeral in parentheses following the name of the ion. The this roman numeral is equal to the charge on the ion. We don’t include the “+” because all metal ions are positive. Here are two more examples: Pb4+ = “lead (IV) ion” Cr3+ = “chromium (III) ion Similarly, when naming a compound containing one of these transition metals, you must include the Roman numeral as well. “Iron Chloride” isn’t specific enough since the compound could contain either iron (II) or iron (III) ion. You must specify the charge on the iron. Iron (II) chloride contains the Fe2+ ion. When combined with chloride, Cl-, we know the formula must be FeCl2. Iron (III) chloride contains the Fe3+ ion. This time, three chlorides are required to form a neutral compound. Therefore, the formula is FeCl3. By looking at the formula of an ionic compound, we can determine the charge (oxidation state) of the metal. Example: Write the name of Co2O3 1. Recognize that Co, cobalt, is a transition metal. This means that you must include a Roman numeral after its name. So, the basic name will be Cobalt (__) Oxide. 2. To find the charge on cobalt, use oxide as a key. Oxide has a charge of –2 so three oxides will have a charge of –6. 3. What balances a –6 charge? A +6 charge! So, the positive half of the compound must equal +6. 4. Since there are two cobalt ions, the charge is split between them. So, each one has a +3 charge. Therefore, we are using the Co3+ ion and the compound is called cobalt (III) oxide. 12 Remember that anions (negative ions) always have a definite charge. When dealing with compounds containing transition metals, look to the anion first. Determine the charge of the anion and then solve to figure out the charge of the cation. When dealing with metals other than the transition metals, you don’t need Roman numerals. In other words, calcium ion, Ca2+ is always +2. Don’t call CaCl2 “calcium (II) chloride.” Its name is “calcium chloride.” B4 Practice: Naming Binary Ionic Compounds Name of Ionic Compound Formula of Ionic Compound 1. Copper (II) sulfate 2. Copper (I) oxide 3. Chromium (III) cyanide 4. Cobalt (II) hydroxide 5. Silver bromide 6. Zinc nitrate 7. Iron (III) acetate 8. Lead (IV) sulfate 9. FeCl2 10. PbSO3 11. Co2(CO3)3 12. AgNO3 13. Zn(CN)2 14. CuClO3 15. Cr(OH)3 16. Hg2O 13 C) Polyatomic Ionic Compounds C1: What is a Polyatomic Ions Polyatomic ions contain two or more different atoms (polyatomic means “many atoms”). Here are some common examples: THIS WILL HELP YOU MEMORIZE THE POLYATOMIC IONS! a. ammonium ion, NH4+ (the only positive polyatomic ion you need to know) b. “ATE” ions: contain an atom bonded to several oxygen atoms: Nitrate = NO3- Phosphate = PO43- Sulfate = SO42- Carbonate = CO32- Acetate = CH3CO2- Chlorate = ClO3- c. “ITE” ions: remove one oxygen from the “ATE” ion and keep the same charge: Nitrite = NO2- Phosphite = PO33- Sulfite = SO32- Chlorite = ClO2d. Other common complex ions: Hydroxide = OH- Cyanide = CN- C2: How to name Ionic Compounds Containing Polyatomic Ions As you’ve already learned, ionic compounds are formed by the combination of a positive ion (cation) and a negative ion (anion). This is the same when dealing simple ions or complex ions. Be careful to note, however, that complex ions are grouped together and should not be separated. In other words, don’t ever separate the sulfate ion, SO42- into sulfur and oxygen. If it’s written as a group, keep it as a group! Since complex ions come in groups, things can get tricky when using subscripts. As a result, we use parentheses to separate the ion from the subscript: If we need two sulfates in a compound, we write: (SO4)2. If we need three nitrates in a compound, we write: (NO3)3. And, just as before, the net charge of the compound must be zero. For a salt containing sodium ion, Na+, and nitrate, NO3-, the ratio would be 1:1 since the positive and negative charges cancel out. Therefore, the formula is NaNO3 and is called sodium nitrate. (Note: no parentheses are necessary here). For a salt containing calcium ion, Ca2+, and nitrate, NO3-, the ratio must be 1:2 (one calcium ion for every two nitrates). So, the formula would be Ca(NO3)2. 14 C2 Practice: How to name Ionic Compounds Containing Polyatomic Ions Name of Ionic Compound Formula of Ionic Compound 1. Sodium chromate 2. Calcium carbonate 3. Magnesium nitrate 4. Aluminum sulfate 5. Lithium phosphate 6. Ammonium chloride 7. Cesium chlorate 8. Potassium sulfate 9. Barium acetate 10. Rubidium cyanide 11. KCH3CO2 12. Mg3(PO4)2 13. Al(ClO3)3 14. CaSO4 15. Sr(HCO3)2 16. NaNO3 17. Li2CO3 18. Ba(NO3)2 19. Cs2CrO4 20. NH4OH 15 D) Acids and bases D1: What is an acid and a base? Acids and bases are ionic compounds with one difference. Acids always have hydrogen as the cation and some other anion Bases always have OH-1 as the anion with some metal as the cation: D2: Naming Acids To start, acids and bases are named the SAME WAY we learned how to name ionic compounds because they are ionic compounds However there is more to naming acids and bases as seen below ACIDS: Oxyacids = oxygen containing, Non-oxyacds = non oxygen containing 16 D3: Naming Bases Naming bases is much easier. In a sense it is the SAME way we name polyatomic ions where the ANION is hydroxide. D2 and D3 Practice: Naming acids and Bases Write the formula for these acids 1. Nitric acid 2. Chloric acid 3. Acetic acid 4. Nitrous acid 5. Hydrofluoric acid Write the name of these acids 6. HNO2 7. HI (aq) 8. HC2H3O2 9. H2CO3 10. H2SO3 Fill in the blank for these acids and bases 19. NaOH 20. Magnesium hydroxide 21. Ammonium hydroxide 22. Ca(OH)2 Great Practice! Write the formulas for the following: a. Barium sulfate ________________ 17 a. CuSO4 _____________________ b. Ammonium chloride _____________ b. PCl3 _______________________ c. Chlorine monoxide _____________ c. Li3N _______________________ d. Silicon tetrachloride ____________ d. BaSO3 _____________________ e. Magnesium fluoride ____________ e. N2F4 _______________________ f. Sodium oxide ________________ f. KClO4 _______________________ g. Sodium peroxide _____________ g. NaH ________________________ h. Copper (i) oxide _____________ h. (NH4)2Cr2O7 ___________________ i. Zinc sulfide _________________ i. HNO2 * _______________________ j. Potassium carbonate ___________ j. Sr3P2 ________________________ k. Hydrobromic acid ____________ k. Mg(OH)2 _____________________ l. Perchloric Acid ______________ l. Al2S3 ________________________ m. Lead (ii) acetate _____________ m. AgBr ________________________ n. Sodium permanganate ____________ n. P4O10 _______________________ o. Lithium oxalate _______________ o. HC2H3O2 * ___________________ p. Potassium cyanide ______________ p. CaI2 _________________________ q. Iron (iii) hydroxide ______________ q. MnO2 _______________________ r. Silicon dioxide _________________ r. Li2O _________________________ s. Nitrogen trifluoride _____________ s. FeI3 _________________________ t. Chromium (iii) oxide _____________ t. Cu3PO4 ______________________ u. Calcium chlorate ________________ u. PCl5 _________________________ v. Sodium thiocyanate ______________ v. NaCN _______________________ w. Nitrous acid ____________________ w. HF * ________________________ * - Name as acids 18