Naming and Counting Atoms and Molecules--Schedule and Homework

(11 days)

Labs: The Masses of Equal Volumes of Gases, The Gross Method, Conservation of Mass During a Chemical Change

1.	Use a periodic table to identify the following elements from their symbols:
	a) S8 b) Fe c) Au d) P e) H2 f) C g) O h) Co i) Hg2
2.	Which of the above elements occur in molecular form? Which of the above are metals? Which are nonmetals?
3.	Compounds occur when atoms of more than one type of element are grouped together. Identify the type of element and the number of its atoms in the compounds below: a) H2O b) CH4 c) C6H12O6 d) CuCl2 e) Fe(NO3)3 f) CH3COOH g) Pb(C2H5)4
4.	List the main ideas of Dalton's atomic theory.
5.	From your notes, compare and contrast 22.4 L of O2 , N2, and HCl gas at 0 oC and 1 atmosphere of pressure. What are some simple ideas that could account for the similarities and differences?
6.	A white substance, on heating, forms a colorless gas and a purple solid. Is the substance an element or a compound? Why do you think so?
7.	In addition to other ingredients, a pumpkin pie recipe calls for 2 cups of pumpkin, 2.5 cups of sugar, and one-half a teaspoon of ginger. Each pie is cut into six pieces. How many cups of pumpkin, cups of sugar, and teaspoons of ginger are in 2.5 pieces? Show your work using the factor-label method.
	There are two types of compounds: Molecular--consists of two or more non-metallic atoms (e.g. CO, OF2, CH4, etc.) Ionic– consists of a metal atom(s) combined with non-metal atoms (Fe2O3, CaO, Ca(NO3)2, etc.)
8.	Write an "m" beside the compounds below that are molecular and an "i" beside those that are ionic. Identify the number and type of atoms in each compound. a) H2O b) CuCl2 c) CuCl d) NO e) NO2 f) C6H12O6 g) NaCl h) C6H6 i) Al2(SO4)3 j) CaCO3
	Molecular compounds that have only two types of atoms (binary) are pretty simple to name. (There is no easy way to name molecular compounds with more than 2 atoms.) A prefix is used before each element's name. (See Table 6.5 on page 159 of your text for a list of proper prefixes.) In addition, the second element's name is changed to end in "ide.") e.g. SO2 = monosulfur dioxide* N2O4 = dinitrogen tetroxide P4S10 = tetrasulur decasulfide * for most compound the prefix "mono" us usually omitted so SO2 is usually called sulfur dioxide
9.	Write the formulas for these binary molecular compounds a) hydrogen chloride b) sulfur dichloride c) nitrogen trifluoride d) dinitrogen difluoride e) sulfur hexafluoride f) dinitrogen pentasulfide g) carbon disulfide h) phosphorus pentachloride:
10.	Write names for the following binary molecular compounds (read section 2-7): a) N2O5 b) OF2 c) NF3 d) P2O3
11.	Refer to your ion sheet or pages 144 - 147 of your text to answer the following: a) Write the formulas and charge of the following metallic cations: zinc copper (I) calcium sodium arsenic (III) plombic plombous b) Write the names of the following metallic cations: K+ Mg+2 Mn2+ Al3+ Fe2+ Cr3+ Sn4+ c) Write the formulas and charge of the following anions: chloride sulfide oxide nitrate nitrite hydrogen carbonate cyanide d) Write the names of the following anions: N3- F- S2- C2H3O2- HSO4- SO42- PO43-
	Ionic compounds consist of metals combined with one or more non-metals. When dissolved in water, ionic compounds conduct electricity. This is evidence that ionic compounds separate into positive and negative charges. It is important to keep the following guidelines in mind: The metal part of the compound is always listed first and is positively charged (the cation). The name of the cation is simple the name of the metallic element listed in the periodic table. After you have identified the metal, the rest of the compound is negatively charged (the anion). If the anion is a single element, its name is the same as that listed on the periodic table but ends with the suffix "ide." If the anion is made up of more than one element, you will have to look up its name in the list of ions. e.g. For NaCl the cation = Na+ (sodium) while the anion is Cl- (Chloride) For Mg(OH)2 the cation = Mg2+ (magnesium) while the anion is OH- (hydroxide)
12.	Identify and name the cation (+ ion) and the anion (- ion) for following ionic compounds. You will have to make use of the ion tables. a) KCl b) BaSO4 c) LiOH d) Sr(NO3)2 e) Cd(C2H3O2)2
	Writing the formulas from the names of ionic compounds can sometimes be tricky. The compounds are neutral when they combine with each other. (The sum of the positive charges must equal the sum of the negative charges.) When writing formulas of ionic compounds, follow this procedure: 1) The first name of the compound is the metal. Look up its name and charge. Write down the symbol and charge of the ion. 2) The second name of the compound is the anion. Look up its name and charge in section 2-8. Write down its symbol and charge. 3) Decide how many positive and negative ions you need to make the charges equal to one another and write the formula.   Compound Name Metal Ion Non-Metal Ion Formula (Charges have to equal)) e.g. aluminum hydroxide: 1) aluminum = Al3+ 2) hydroxide = OH- 3) Formula = Al(OH)3   tin (II)oxide: 1) tin(II) = Sn2+ 2) oxide = O2- 3) Formula = SnO   ammonium sulfate 1) ammonium = NH4+ 2) sulfate = SO42- 3) Formula = (NH4)2SO4
13.	Write the formulas of the following ionic compounds. (Remember that the compound must be electrically neutral.) a) tin (II) hydroxide b) barium fluoride c) iron (III) oxalate d) calcium sulfide e) sodium phosphate f) potassium perchlorate g) aluminum hydrogen carbonate
14.	Decide whether the compounds below are ionic or molecular. If they are molecular, determine their names using the table of prefixes on page 159 of your text. If they are ionic, determine their names using your sheet of ions. a) CS2 b) SO2 c) NaOH d) P2S3 e) CF4 f) FeCl3 g) Mg(HSO4)2 h) Cu2SO4
15.	Decide whether the compounds below are ionic or molecular. Use your reading and your tables of ions to determine the formulas of the compounds. a) Carbon Tetrafluoride b) Calcium Iodide c) Sodium Phosphate d) Tin (II) oxide e) Sulfur Hexafluroide e) Lead (IV) nitrate
	By comparing the masses containers of gases, early scientists determined the relative masses of gas molecules. By studying the volumes produced when gases are combined, the number of atoms in gas molecules could be deduced. In this manner the relative masses of atoms were found and printed in the periodic table. In your tables, the relative atomic masses are the bottom number printed in each element's box. The masses are given in atomic mass units (amu) which used to understood to be the number of times a number is heavier than a hydrogen atom. e.g. The atomic mass of magnesium (Mg) = 24.305 amu or a magnesium atom is about 24.305 times heavier than a hydrogen atom.
16.	Find the relative atomic mass of each of the elements below: a) Uranium b) Silicon c) Neon d) Titanium
	The relative mass of a molecule can be found by adding up the masses of the atoms that make up the molecules. e.g. O2 = 15.999 amu + 15.999 amu = 32 amu CH4 = 12.011 + 1.001 + 1.001 + 1.001 + 1.001 = 16 amu CO2 = 12.011 amu + 15.999 amu + 15.999 amu = 44 amu
17.	Find the relative molecular mass of the following compounds: a) AlCl3 b) H2O c) Ba(NO3)2 d) nitrogen dioxide e) sodium chloride
18.	Decide whether the compounds below are ionic or molecular. If they are molecular, determine their names using the table of prefixes in section 2-7 of your reading. If they are ionic, determine their names using your sheet of ions. a) SiCl4 b) ZnCO3 c) Ni(NO2)3 d) Br2O
19.	Decide whether the compounds below are ionic or molecular. Use your reading and your tables of ions to determine the formulas of the compounds. a) Aluminum Fluoride b) Carbon Tetrabromide c) Cobalt (II) Acetate
	The mole is a tool used by chemists to count atoms and molecules. 1 mole2 = 6.02 x 1023 molecules or atoms = the atomic or molecular mass found on the periodic table = 22.4 L of any gas at 0 oC and 1 atm pressure (STP) 1 mole of CO2 molecules2 = 6.02 x 1023 CO2 molecules = 12 + 16 + 16 = 32 g = 22.4 L at STP = 6.02 x 1023 C atoms
20.	Use the periodic table to find the mass of one mole (molar mass) of the following: a) Hydrogen gas (H2) b) Copper Atoms c) Water Molecules d) Sodium Sulfate (Na2SO4) e) Dinitrogen Pentoxide f) Iron (III) Oxide
21.	How many oxygen atoms are in one mole of nitric acid (HNO3) molecules? of sulfuric acid (H2SO4) molecules?
22.	Use the factor-label method to find the number of grams in each of the following: a) 3.0 moles of oxygen molecules b) 1.5 moles of sulfuric acid (H2SO4) c) 10.0 moles of water molecules d) 2.5 moles of phosphoric acid (H3PO4) e) 1000 moles of nitric acid (HNO3)
23.	Use the factor-label method to find the mass of the following: a) one water molecule (H2O) b) one oxygen molecule (O2) c) one hydrogen atom (H) d) one million uranium atoms (U) e) one hundred silver atoms (Ag) f) one billion gold atoms (Au)
24.	An average person has a mass of 75 Kg and is mostly water. How many moles of water is this? How many water molecules are present in an average human?
25.	A flask of gaseous CCl4 was weighed at a certain temperature and pressure. The flask was flushed and filled with oxygen gas at the same temperature and pressure. The mass of the CCl4 vapor will be about: (Choose one of the following and explain your answer.) a) the same as that of oxygen b) 1/5 as heavy as oxygen c) 5 times heavy as the oxygen d) twice as heavy as the oxygen e) one-half as heavy as the oxygen
26.	A chemist weighs out 10.0 g of chlorine gas and 10.0 grams of sulfur dichloride. How many moles of each substance does she have?
27.	How many moles of atoms are there in 9.0 grams of aluminum? In 0.83 g of iron?
28.	How many moles are there in 53 g of phosphoric acid, H3PO4?
29.	Our balance can detect 0.01 g of any substance. How many atoms of gold would there be in such a sample?
30.	How many grams of table sugar (C12H22O11) are needed to supply one molecule for each of the 5 x 109 people on Earth?
31.	There are two common oxides of sulfur. One contains 32 g of sulfur for each 32 g of oxygen. The other oxide contains 32 g of sulfur for each 48 g of oxygen. What are the empirical formulas of these oxides?
32.	A variety of phosphorus called red phosphorus is used in match heads. When 0.062 g of red phosphorus burns 0.142 g of phosphorus oxide is formed. a) How many grams of oxygen combine with the phosphorus to form phosphorus oxide? b) What is the empirical formula of the oxide?
33.	There are only two compounds containing only tungsten and carbon. One is the very hard alloy, tungsten carbide, used for the edges of cutting tools. Analysis of the two compounds gives for one, 1.82 g of tungsten per 0.12 g of carbon, and for the other compound, 3.60 g of tungsten per 0.12 g of carbon. What are the empirical formulas for these compounds?

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