1. Chapter 4 Lecture Basic Chemistry Fourth Edition Chapter 4 Atoms and Elements 4.4 Atomic Number and Mass Number Learning Goal Given the atomic number and the mass number of an atom, state the number of protons, neutrons, and electrons. © 2014 Pearson Education, Inc.

2. The atomic number is specific for each element and the same for all atoms of that element is equal to the number of protons in an atom appears above the symbol of an element Atomic Number Chemical Symbol © 2014 Pearson Education, Inc. Atomic Number 11 Na

3. © 2014 Pearson Education, Inc. Hydrogen has atomic number 1; every H atom has 1 proton. Carbon has atomic number 6; every C atom has 6 protons. Copper has atomic number 29; every Cu atom has 29 protons. Gold has atomic number 79; every Au atom has 79 protons. Atomic Numbers and Protons

4. © 2014 Pearson Education, Inc. Atomic Models

5. © 2014 Pearson Education, Inc. State the number of protons in each atom. A.A nitrogen atom (1) 5 protons(2) 7 protons(3) 14 protons B.A sulfur atom (1) 32 protons (2) 16 protons(3) 6 protons C.A barium atom (1) 137 protons (2) 81 protons(3) 56 protons Learning Check

6. © 2014 Pearson Education, Inc. State the number of protons in each atom. A. A nitrogen atom(2) 7 protons B. A sulfur atom(2) 16 protons C. A barium atom(3) 56 protons Solution

7. © 2014 Pearson Education, Inc. An atom of any element is electrically neutral; it has a net charge of zero has an equal number of protons and electrons A neutral atom of calcium, atomic number 20, contains 20 protons and 20 electrons. It has zero net charge. Atoms Are Neutral

8. © 2014 Pearson Education, Inc. The mass number represents the number of particles in the nucleus is equal to the number of protons + number of neutrons does not appear on the periodic table because it applies to a single atom only Mass Numbers

9. © 2014 Pearson Education, Inc. We calculate the number of neutrons in an atom from its mass number and atomic number: mass number – atomic number = number neutrons Potassium has a mass number of 39 and an atomic number of 19. To find the number of neutrons, subtract the atomic number from its mass number. 39 (mass number) – 19( atomic number) = 20 neutrons Mass Numbers - Neutrons

10. © 2014 Pearson Education, Inc. Composition of Elements

11. © 2014 Pearson Education, Inc. An atom of zinc has a mass number of 65. A. How many protons are in the nucleus? (1) 30 (2) 35(3) 65 B.How many neutrons are in the nucleus? (1) 30(2) 35(3) 65 C. What is the mass number of a zinc atom that has 37 neutrons? (1) 37(2) 65(3) 67 Learning Check

12. © 2014 Pearson Education, Inc. An atom of zinc has a mass number of 65. A. How many protons are in the nucleus? (1) 30 B.How many neutrons are in the nucleus? (2) 35 C. What is the mass number of a zinc atom that has 37 neutrons? (3) 67 Solution

13. © 2014 Pearson Education, Inc. An atom has 14 protons and 20 neutrons. A. Its atomic number is (1) 14 (2) 16(3) 34 B. Its mass number is (1) 14 (2) 16(3) 34 C. The element is (1) Si (2) Ca(3) Se Learning Check

14. © 2014 Pearson Education, Inc. An atom has 14 protons and 20 neutrons. A.Its atomic number is (1) 14 B.Its mass number is (3) 34 C.The element is (1) Si Solution