1. Orginally prepared and distributed by Jefferson Lab Office of Science Education education.jlab.org/jsat/powerpoint/chembond.ppt

3. Chemical Bond force that holds two atoms together

4. Chemistry is all about electrons! a)Atomic number = number of protons so also number of electrons. b)Electrons fill energy levels and sublevels in a predictable pattern (periodic table as block diagram: s, p, d, f ) c)Outermost electrons are known as valence electrons

5. Valence electrons determine reactivity and stability of elements. Valence electrons will be lost, gained or shared in order to obtain a stable configuration like a noble gas OCTET RULE

6. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons C would like to N would like to O would like to Gain or lose 4 electrons Gain 3 electrons Gain 2 electrons

7. Electron Dot Structures 1 2 13 14 15 16 17 18

8. Learning Check A. X would be the electron dot formula for 1) Na2) K3) Al B. X would be the electron dot formula 1) B2) N3) P

9. Learning Check A. X would be the electron dot formula for 1) Na2) K B. X would be the electron dot formula 2) N3) P

10. IONIC BOND valence electrons are transferred between a metal and a non-metal forming positively and negatively charged particles electrostatic attractive force

11. Formation of Metal Ions Metals lose electrons to match the number of valence electrons of their nearest noble gas Positive ions form when the number of electrons are less than the number of protons Group 1 metals lose 1e - ion 1+ Group 2 metals lose 2e - ion 2+ Group 13 metals lose 3e - ion 3+

12. Formation of Sodium Ion Sodium atom Sodium ion Na  ( - 1e - ) Na + 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 ( like Ne) 11 p + 11 p + 11 e - 10 e - 0 1 +

13. Formation of Magnesium Ion Magnesium atom Magnesium ion   Mg  ( - 2e - ) Mg 2+ 1s 2 2s 2 2p 6 3s 2 1s 2 2s 2 2p 6 (like Ne) 12 p + 12 p + 12 e- 10 e - 0 2 +

14. Some Typical Ions with Positive Charges (Cations) Group 1Group 2Group 13 H + Mg 2+ Al 3+ Li + Ca 2+ Na + Sr 2+ K + Ba 2+

15. Learning Check A. Number of valence electrons in aluminum 1) 1 e - 2) 2 e - 3) 3 e - B. Change in electrons for octet 1) lose 3e - 2) gain 3 e - 3) gain 5 e - C.Ionic charge of aluminum 1) 3- 2) 5- 3) 3 +

16. Solution A. Number of valence electrons in aluminum 3) 3 e - B. Change in electrons for octet 1) lose 3e - C.Ionic charge of aluminum 3) 3 +

17. Learning Check Give the ionic charge for each of the following: A. 12 p + and 10 e - 1) 02) 2+3) 2- B. 50p + and 46 e- 1) 2+2) 4+3) 4- C. 15 p + and 18e- 2) 3+ 2) 3-3) 5-

18. Learning Check Give the ionic charge for each of the following: A. 12 p + and 10 e - 2) 2+ B. 50p + and 46 e- 2) 4+ C. 15 p + and 18e- 2) 3-

19. Formation of Nonmetal Ions (anions) Nonmetals in 15, 16, and 17 gain electrons from metals to form negative ions Nonmetals gain electrons to achieve the octet arrangement Nonmetal ionic charge: 3-, 2-, or 1-

20. Fluoride Ion 1s 2 2s 2 2p 5 unpaired electron octet   : F  + e -  : F : F -   9 p+ 9 p + 9 e- 10 e- 1s 2 2s 2 2p 6 0 1 -

21. Ionic Bond Between atoms of metals and nonmetals Electrons transferred resulting in positively & negatively charged ions – strong attraction! Examples: NaCl, CaCl 2, K 2 O

23. Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na + ) and the Cl becomes (Cl - ), charged particles or ions – attactive force between then!

24. Strong attractive force - ionic compounds are all solids at room temp.