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# Com 2 '7 az 112

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Definition of A, Z and isotopes

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• The mass # is written as a left superscript. While the element’s at. # is written as a left subscript
• The mass # is written as a left superscript. While the element’s at. # is written as a left subscript
• ### Com 2 '7 az 112

1. 2. The periodic table is arranged in order of increasing atomic number
2. 3. ATOMIC NUMBER Number of protons in an atom
3. 4. ATOMIC NUMBER Z
4. 7. An individual atom is electrically neutral protons = electrons
5. 8. How many protons and electrons are in an oxygen atom?
6. 10. OXYGEN Z = 8
7. 11. protons = 8 electrons = 8 OXYGEN Z = 8
8. 12. URANIUM Z = 92 protons = 92 electrons = 92
9. 13. MASS NUMBER A
10. 14. Total number of protons and neutrons in an atom of a given isotope MASS NUMBER
11. 15. Mass Number Mass number is the number of protons and neutrons in the nucleus of an isotope. 8 8 18 18 Arsenic 75 33 75 Phosphorus 15 31 16 Nuclide p + n 0 e - Mass # Oxygen - 10 - 33 42 - 31 15
12. 16. CARBON's mass # A = 12
13. 17. U's mass # A = 238
14. 18. A x z Mass # At. #
15. 19. Write the symbol for the atom that has an atomic number of 9 and a mass number of 19.
16. 20. 19 F 9
17. 21. How many electrons and how many neutrons does the atom have? 19 F 9
18. 22. How many electrons and how many neutrons does the atom have? 19 F 9 number of neutrons = mass # - at. # A= 19 Z = 9 = 10 neutrons # of neutrons = A- Z # of neutrons = 19 - 9
19. 23. 31 X 15 Identify the element
20. 24. 173 X 70 Identify the element
21. 25. CARBON 6 protons 6 neutrons
22. 26. URANIUM 92 protons 146 neutrons
23. 27. All atoms of the same element do not necessarily have the same number of neutrons in their nuclei
24. 28. Atoms of the same element that have different number of neutrons ISOTOPES
25. 29. Isotopes…Again (must be on the test) Isotopes are atoms of the same element having different masses due to varying numbers of neutrons . Isotope Protons Electrons Neutrons Nucleus Hydrogen–1 (protium) 1 1 0 Hydrogen-2 (deuterium) 1 1 1 Hydrogen-3 (tritium) 1 1 2
26. 30. When an atom loses or gains an electron IONS
27. 31. More protons than electrons positive charge + CATION
28. 32. More electrons than protons negative charge - ANION
29. 33. 24 Mg 12 How many p+, e- and neutrons are present in the following atom or ion ?
30. 34. 24 Mg 12 24 Mg 2+ 12 Mg atom – neutral 12 p+, 12 e- If it loses 2e- ??? What is it’s charge? # of p+ = +12 # of e- = -10 + 2 Magnesium cation
31. 35. Write the chemical symbol for the ion with 9 protons and 10 electrons 19 F -1 9
32. 36. 27 Al +3 # of neutrons = 27 - 13 = 14
33. 37. Write the chemical symbol for the ion with 7 protons and 10 electrons 14 N -3 7
34. 38. How many protons and electrons are present in the S -2 ion? 32 S -2 16
35. 39. Initial Appearance of Each Metal Metal Reactivity Metal Initial Appearance             Metal Cu(NO3)2 Cu+2 Mg(NO3)2 Mg+2 Zn(NO3)Zn+2 AgNO3 Ag+ Cu         Mg         Zn