2. 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 2

3. ParticleSymbol Charge Relative Mass Electron e - 1- 0 Proton p + + 1 Neutron n0 1 3

4.  Atoms are composed of 2 regions: Nucleus Electron Cloud

5.  Nucleus: the center of the atom that contains the mass of the atom  Electron cloud: region that surrounds the nucleus that contains most of the space in the atom

6. 6  Number of protons in an atom  All atoms of an element have the same number of protons

7. 7 11 Na Atomic Number Symbol

8. 8 11 Na 11 Protons Sodium

9. 9 State the number of protons for atoms of each of the following: Nitrogen

10. 10 7 N 7 Protons Nitrogen

11. 11 State the number of protons for atoms of each of the following: Sulfur

12. 12 16 S 16 Protons Sulfur

13. 13 State the number of protons for atoms of each of the following: Barium

14. 14 56 Ba 56 Protons Barium

15. 15  Counts the number of protons and neutrons in an atom  Mass number= p + + n 0

16. 16 Show the mass number and atomic number Give the symbol of the element

17. 17 Na Mass number Atomic number 11 23

18. 18 Cl Mass number Atomic number 17 35 How many protons? What is the element? How many neutrons?

19. 19 Cl Mass number Atomic number 17 35 What is the element? Chlorine

20. 20 Cl Mass number Atomic number 17 35 How many protons? p = atomic # = 17

21. 21 Cl Mass number Atomic number 17 35 How many neutrons? n 0 = 35 (mass number– 17 (p + ) n 0 = 18

22. 22 An atom is neutral The net charge is zero Number of protons = Number of electrons Atomic number = Number of electrons

23. 23 O 8 16 n 0 = p + = e - = 8 8 8

24. 24 P 15 31 n 0 = p + = e - = 15 16 15

25. 25 Zn 30 65 n 0 = p + = e - = 30 35 30

26. 26 Atoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers

27. 27 Isotopes of chlorine 35 Cl 37 Cl 17 chlorine - 35 chlorine - 37

28. LecturePLUS Timberlake28 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 6 6 6 #p _______ _______ _______ #n _______ _______ _______ #e _______ _______ _______

29. LecturePLUS Timberlake29 12 C 13 C 14 C 6 6 6 #p 6 6 6 #n 6 7 8 #e 6 6 6

30. 30 An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom B.Number of neutrons in the zinc atom C. What is the mass number of a zinc isotope with 37 neutrons? Draw its atomic symbol.

31. 31 An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 30

32. 32 An atom of zinc has a mass number of 65. B.Number of neutrons in the zinc atom 35

33. 33 C. What is the mass number of a zinc isotope with 37 neutrons? Draw its atomic symbol. 67 Zn 30 67

34. 34 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 - ___________

35. 35 16 O A. 8 p +, 8 n, 8 e - 8 B.17p +, 20n, 17e - 37 Cl 17 C. 47p +, 60 n, 47 e - 107 Ag 47

36. 36 11 Na 22.99 Atomic Number Symbol Atomic Mass

37. 37  Atomic mass is the weighted average mass of all the atomic masses of the isotopes of that atom.

39.  Ion – charged particle that forms when an atom gains or loses one or more electrons

40.  Cation – positively charged particle when an atom loses electrons protons(+) > electrons(-1)

41. Ca +2 protons(+) = 20 electrons(-) = 18

42.  Anion – negatively charged particle when an atom gains electrons electrons(-) > protons(+)

43. N -3 protons(+) = 7 electrons(-) = 10