University:
Miami University
Course:
CHM 141 | College Chemistry
Academic year:

2022
Views:

429

Pages:

2
Author:

ilikemyicons0y5

Name: ______________________________________________ Period:______ Due Date:_________ Atoms and Molecules Homework - Answers 1. Describe the difference between atoms, molecules and compounds. Atoms are the smallest particle of a given element that retains the elements chemical properties. A molecule is a collection of two or more atoms of the same or different element in definite arrangements that are chemically bonded together. Molecules which contain different types of atoms are called compounds. 2. Use your knowledge of subscripts and coefficients to complete the table below: Name Formula Number of Atoms in the Substance. Calcium carbonate CaCO3 Ca -1 C-1 O3 – 3 Total =5 Magnesium hydroxide Mg(OH)2 Mg -1 O-2 H–2 Total = 5 Acetic acid 2C2H4O2 C2 -2 H4 - 4 O2 – 2 Total = 8 x 2 = 16 Calcium chloride CaCl2 Ca – 1 Cl2 – 2 Total = 3 Sulfuric acid H2SO4 H2 - 2 S -1 O4 – 4 Total = 7 Sodium phosphate 2Na3PO4 Na3 - 3 P-1 O4 -4 Total = 8 x 2 = 16 Aluminium hydroxide Al(OH)3 Al - 1 O-3 H–3 Total = 7 Ammonium sulfate 4(NH4)2SO4 N–2 H4 - 8 S -1 O4 – 4 Total = 15 x 4 = 60 Name: ______________________________________________ Period:______ Due Date:_________ Atoms and Molecules Homework - Answers 3. For each of the following compounds, outline the number of named atoms. a. The number of chlorine atoms in paradichlorobenzene (moth crystals) 4C6H4Cl2. Cl2 = 8 b. The number of carbon atoms in Aspirin (pain relief) 2C9H8O4. C9 = 9 x 2 = 18 c. The number of nitrogen atoms in trinitrotoluene (explosive) C7H5(NO2)3. N= 3 d. The number of hydrogen atoms in cellulose (plant tissue) 3C6H7O2(OH)3. H7 + H3 = H10 H10 x 3 = 30 e. The number of hydrogen atoms in calcium dihydrogen phosphate (fertilizer) 2Ca(H2PO4)2. H=2x2x2=8 f. The number of oxygen atoms in lanthanum carbonate (kidney medicine) 3 La2(CO3)3. O = 3 x 3 x 3 = 27