1. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.1 Writing Chemical Symbols a. Ni b. N c. Ne Study Check 3.1 What are the chemical symbols for the elements silicon, sulfur, and silver? Solution What are the chemical symbols for the following elements? a. nickel b. nitrogen c. neon

2. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.2 Names and Symbols of Chemical Elements a. zinc b. potassium c. hydrogen d. iron Study Check 3.2 What are the names of the elements with the chemical symbols Mg, Al, and F? Solution Give the name of the element that corresponds to each of the following chemical symbols: a. Zn b. K c. H d. Fe

3. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.3 Group and Period Numbers of Some Elements a. Iodine (I), Period 5, Group 7A (17), is a representative element. b. Manganese (Mn), Period 4, Group 7B (7), is a transition element. c. Barium (Ba), Period 6, Group 2A (2), is a representative element. d. Gold (Au), Period 6, Group 1B (11), is a transition element. Study Check 3.3 Strontium is an element that gives a brilliant red color to fireworks. a. In what group is strontium found? b. In what chemical family is strontium found? c. In what period is strontium found? d. What are the name and symbol of the element in Period 3 that is in the same group as strontium? e. What alkali metal, halogen, and noble gas are in the same period as strontium? Solution Give the period and group for each of the following elements and identify as a representative or transition element: a. iodine b. manganese c. barium d. gold

4. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.4 Metals, Nonmetals or Metalloids a. Na (sodium), Group 1A (1), Period 3, is an alkali metal. b. I (iodine), Group 7A (17), Period 5, halogen, is a nonmetal. c. B (boron), Group 3A (13), Period 2, is a metalloid. Study Check 3.4 Give the name and symbol of the following elements: a. Group 5A (15), Period 4 b. A noble gas in Period 3 c. A metalloid in Period 3 Solution Use the periodic table to classify each of the following elements by its group and period, group name (if any), and as a metal, nonmetal, or metalloid: a. Na b. I c. B

5. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.5 Identifying Subatomic Particles a. neutron b. electron c. proton Study Check 3.5 Is the following statement true or false? The nucleus occupies a large volume in an atom. Solution Identify the subatomic particle that has the following characteristics: a. no charge b. a mass of 0.000 55 amu c. a mass about the same as a neutron

6. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.6 Using Atomic Numbers to Find the Number of Protons and Electrons a. atomic number 7; 7 protons and 7 electrons b. atomic number 12; 12 protons and 12 electrons c. atomic number 35; 35 protons and 35 electrons Study Check 3.6 Consider an atom that has 79 electrons. a. How many protons are in its nucleus? b. What is its atomic number? c. What is its name, and what is its symbol? Solution Using the periodic table in Figure 3.1, state the atomic number, number of protons, and number of electrons for an atom of each of the following elements: a. nitrogen b. magnesium c. bromine

7. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.7 Calculating Numbers of Protons, Neutrons and Electrons a. Zinc (Zn), with an atomic number of 30, has 30 protons. b. The number of neutrons in this atom is found by subtracting the atomic number from the mass number. Mass number – atomic number = number of neutrons c. Because the zinc atom is neutral, the number of electrons is equal to the number of protons. A zinc atom has 30 electrons. Study Check 3.7 How many neutrons are in the nucleus of a bromine atom that has a mass number of 80? Solution For an atom of zinc that has a mass number of 68, determine the following: a. the number of protons b. the number of neutrons c. the number of electrons 68 – 30 = 38

8. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.8 Identifying Protons and Neutrons in Isotopes The atomic number of Ne is 10, which means that the nucleus of each isotope has 10 protons. The number of neutrons in each isotope is found by subtracting the atomic number (10) from each of their mass numbers. a. 10 protons; 10 neutrons (20 – 10) b. 10 protons; 11 neutrons (21 – 10) c. 10 protons; 12 neutrons (22 – 10) Study Check 3.8 Write an atomic symbol for each of the following: a. a nitrogen atom with 8 neutrons b. an atom with 20 protons and 22 neutrons c. an atom with mass number 27 and 14 neutrons Solution State the number of protons and neutrons for each of the following isotopes of neon (Ne): a. b. c.

9. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.9 Calculating Atomic Mass Solution Using Table 3.7, calculate the atomic mass for magnesium using the weighted average mass method. 10 5 11 5

10. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.9 Calculating Atomic Mass Study Check 3.9 There are two naturally occurring isotopes of boron. The isotope B has a mass of 10.01 amu with an abundance of 19.80%, and the isotope B has a mass of 11.01 amu with an abundance of 80.20%. What is the atomic mass of boron? Continued 10 5 11 5

11. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.10 Writing Electron Arrangments a. Oxygen with atomic number 8, has eight electrons, which are arranged with two electrons in energy level 1 and six electrons in energy level 2. 2,6 b. Chlorine with atomic number 17, has 17 electrons, which are arranged with 2 electrons in energy level 1, 8 electrons in energy level 2, and 7 electrons in energy level 3. 2,8,7 Study Check 3.10 What element has an electron arrangement of 2,8,5? Solution Write the electron arrangement for each of the following: a. oxygen b. chlorine

12. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.11 Using Group Numbers a. Cesium (Cs) is in Group 1A (1); cesium has one valence electron. b. Iodine (I) is in Group 7A (17); iodine has seven valence electrons. Study Check 3.11 What is the group number of elements with atoms that have five valence electrons? Solution Using the periodic table, write the group number and the number of valence electrons for each of the following elements: a. cesium b. iodine

13. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.12 Writing Electron-Dot Symbols a. Because the group number for bromine is 7A (17), bromine has seven valence electrons, which are drawn as seven dots, three pairs and one single dot, around the symbol Br. b. Aluminum, in Group 3A (13), has three valence electrons, which are shown as three single dots around the symbol Al. Study Check 3.12 What is the electron-dot symbol for phosphorus? Solution Write the electron-dot symbol for each of the following: a. bromine b. aluminum

14. © 2012 Pearson Education, Inc. Chemistry: An Introduction to General, Organic, and Biological Chemistry, 11th Edition Karen C. Timberlake Sample Problem 3.13 Ionization Energy a. Na. In Na, the valence electron is closer to the nucleus. b. Cl. Attraction for the valence electrons increases going from left to right across a period. c. F. Attraction for the valence electrons increases going from left to right across a period. Study Check 3.13 Arrange Sn, Sr, and I in order of increasing ionization energy. Solution Indicate the element in each group that has the higher ionization energy and explain your choice. a. K or Na b. Mg or Cl c. F, N, or C