1. Isotopes and Ions VARIATIONS ON THE ATOM

2. Ions! ITS ABOUT PROTONS AND ELECTRONS

3. Ions Ions are when an atom has an unequal number of p + and e - Remember – a stable atom has a neutral overall charge due its equal number of p + and e - When an atom loses or gains an e -, its charge changes accordingly ◦Loss of e - means a + charge; gaining an e - means a – charge for the atom

4. Losing or Gaining e -..... If an atom loses an e -, then it has more p + than e - and it will have an overall positive charge Different elements’ atoms can lose 1, 2, 3, or even 4 electrons depending on various factors If an atom has LOST e -, then it is called a CATION or a positive ion ◦A Cation would be written as Al + (the one being understood) or Al +3

5. Atoms can also gain electrons If an atom gains electrons (from 1 up to 4), then it will have more e - than p + and will end up having an overall negative charge A negatively charged ion is called an ANION ◦The element is shown this like: Na - (the 1 is understood) or Na -2 The losing or gaining of electrons determines what type of bonds the atoms will form, and which atoms will bond to others

7. Ions in Water Solution

8. Using the Periodic Table Elements in the Main Groups (A), form fairly consistent ions – LEARN TO USE THE CHART Group IA will form +1 ions; Group 2A form up to +2; Group 3A form up to +3 ions Group 4A will form either up to -4 or +4 ions Group 5A will form up to -3 ions; Group 6A up to -2; Group 7A form -1; and Group 8A will not form ions at all Those elements in the B groups vary and we’ll learn those later

10. Isotopes ITS ABOUT PROTONS AND NEUTRONS

11. 11 Isotopes are atoms of the same element that have different mass numbers. have the same number of protons, but different numbers of neutrons. Isotopes

12. Atomic Symbol An atomic symbol represents a particular atom of an element. gives the mass number in the upper left corner and the atomic number in the lower left corner. Example: An atom of sodium with atomic number 11 and a mass number 23 has the following atomic symbol: mass number 23 Na atomic number 11 12

13. Information from Atomic Symbols The atomic symbol for a specific atom of an element gives the number of protons (p + ), number of neutrons (n), and number of electrons (e - ). 13

14. Information from Atomic Symbols Examples of number of subatomic particles for atoms Atomic symbol 16 31 65 O P Zn 8 15 30 8 p + 15 p + 30 p + 8 n16 n 35 n 8 e - 15 e - 30 e - 14

15. Learning Check 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 the following: 12 C 13 C 14 C 6 6 6 protons ______ ______ ______ neutrons ______ ______ ______ electrons______ ______ ______ 15

16. 16 12 C 13 C 14 C 6 6 6 protons 6 p + 6 p + 6 p + neutrons 6 n7 n 8 n electrons 6 e - 6 e - 6 e - Solution

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

18. 18 A. 8 p +, 8 n, 8 e - 16 O 8 B. 17p +, 20 n, 17e - 37 Cl 17 C. 47p +, 60 n, 47 e -107 Ag 47 Solution

19. Learning Check 1. Which of the pairs are isotopes of the same element? 2. In which of the pairs do both atoms have 8 neutrons? A. 15 X 15 X 8 7 B. 12 X 14 X 6 6 C. 15 X 16 X 7 8 19

20. 20 Solution B. 12 X 14 X 6 6 The atomic symbols in “B.” represent isotopes of carbon with 6 protons each, but one has 6 neutrons and the other has 8. C. 15 X 16 X 7 8 These isotopes of nitrogen and oxygen have 8 neutrons.

21. Isotopes of Magnesium 21

22. 22 Isotopes of Magnesium

23. 23 Isotopes of Sulfur A sample of naturally occurring sulfur contains several isotopes with the following abundances Isotope % abundance 32 S 95.02 33 S 0.75 34 S 4.21 36 S 0.02 32 S, 33 S, 34 S, 36 S 16 16 Copyright © 2009 by Pearson Education, Inc.

24. Ions and Isotopes in Review Stable atom: #p + = #n 0 = #e - Atomic Mass - #n 0 = # p + Atomic Mass - #p + = #n 0 If charge is 0, then #p + = #e - If charge is positive, then #p + > #e - Cation If charge is negative, then #p + < #e - Anion

25. Examples: Li -1 has gained an electron, meaning there is one more negative charge than positive ones ◦It has 3 p + and 4 e - Li +1 has lost an electron, meaning there is one more positive charge than negative ones ◦It has 3 p + and 2 e - ◦REMEMBER: The # of p + DO NOT CHANGE ◦Only the number of n 0 (isotope) and e - (ion) change

26. Cf -3 has an atomic number of 98 ◦This means it has 98 p + ◦Its atomic mass is 216 ◦It has 118 n 0, (216 – 98), making it an ion and an isotope! ◦Since it has a -3 charge, the number of e - will be 101; (98 + 3) ◦Zn +1 has 30 p + and n 0 ; but due to the +1 charge, it has only 29 e -