1 The Atom Atomic Number and Mass Number Isotopes

2 Atomic Theory Atoms are building blocks of elements Similar atoms in each element Different from atoms of other elements Two or more different atoms bond in simple ratios to form compounds

3 Subatomic Particles ParticleSymbol Charge Relative Mass Electron e Proton p Neutron n0 1

LecturePLUS Timberlake4 Location of Subatomic Particles cm electrons protons neutrons cm nucleus

5 Atomic Number Counts the number of protons in an atom

LecturePLUS Timberlake6 Periodic Table Represents physical and chemical behavior of elements Arranges elements by increasing atomic number Repeats similar properties in columns known as chemical families or groups

7 Periodic Table Na

8 Atomic Number on the Periodic Table 11 Na Atomic Number Symbol

9 All atoms of an element have the same number of protons 11 Na 11 protons Sodium

10 Learning Check AT 1 State the number of protons for atoms of each of the following: A. Nitrogen 1) 5 protons 2) 7 protons 3) 14 protons B. Sulfur 1) 32 protons 2) 16 protons 3) 6 protons C. Barium 1) 137 protons 2) 81 protons 3) 56 protons

11 Solution AT 1 State the number of protons for atoms of each of the following: A. Nitrogen 2) 7 protons B. Sulfur 2) 16 protons C. Barium 3) 56 protons

12 Number of Electrons An atom is neutral The net charge is zero Number of protons = Number of electrons Atomic number = Number of electrons

13 Mass Number Counts the number of protons and neutrons in an atom

LecturePLUS Timberlake14 Atomic Symbols Show the mass number and atomic number Give the symbol of the element mass number 23 Na sodium-23 atomic number 11

15 More Atomic Symbols O P Zn p + p + p + n n n e - e - e -

16 More Atomic Symbols O P Zn p + 15 p + 30 p + 8 n16 n35 n 8 e - 15 e - 30 e -

17 Isotopes Atoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers Isotopes of chlorine 35 Cl 37 Cl17 chlorine - 35 chlorine - 37

LecturePLUS Timberlake18 Learning Check AT 2 Naturally occurring carbon consists of three isotopes, 12 C, 13 C, and 14 C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12 C 13 C 14 C #P _______ _______ _______ #N _______ _______ _______ #E _______ _______ _______

19 Solution AT 2 12 C 13 C 14 C #P __6___ _ 6___ ___6___ #N __6___ _ _7___ ___8___ #E __6___ _ 6___ ___6___

20 Learning Check AT 3 An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 1) 302) 353) 65 B.Number of neutrons in the zinc atom 1) 302) 353) 65 C. What is the mass number of a zinc isotope with 37 neutrons? 1) 372) 653) 67

21 Solution AT 3 An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 1) 30 B.Number of neutrons in the zinc atom 2) 35 C. What is the mass number of a zinc isotope with 37 neutrons? 3) 67

22 Learning Check AT 4 Write the atomic symbols for atoms with the following: A. 8 p +, 8 n, 8 e - ___________ B.17p +, 20n, 17e - ___________ C. 47p +, 60 n, 47 e - ___________

23 Solution AT 4 16 O A. 8 p +, 8 n, 8 e - 8 B.17p +, 20n, 17e - 37 Cl 17 C. 47p +, 60 n, 47 e Ag 47

24 Learning Check AT 5 An atom has 14 protons and 20 neutrons. A.Its atomic number is 1) 142) 163) 34 B. Its mass number is 1) 142) 163) 34 C. The element is 1) Si2) Ca3) Se D.Another isotope of this element is 1) 34 X 2) 34 X 3) 36 X

25 Solution AT 5 An atom has 14 protons and 20 neutrons. A.It has atomic number 1) 14 B. It has a mass number of 3) 34 C. The element is 1) Si D.Another isotope of this element would be 3) 36 X 14