Unit 6 Study Guide Answers

Name __________________ Date ________ Unit 6 Study Guide: Bonding and Balancing Ionic Formulas • Chemical Bonding 1. What is a valence electron? Electron on outer energy level.(outer shell) 2. When are elements stable? When they have a full valence shell (8 electrons) a. When is helium stable? It is always stable because it has two valence electrons 3. Be able to identify how many valence electrons different elements have from groups 1, 2, 13, 14, 15, 16, 17 and 18. a. Na has one valence electron b. Ca two c. N five d. Si four e. I seven f. Kr eight 4. Why do atoms chemically bond? They bond to become more stable. Gets 2 or 8 valence electrons 5. Why do metals tend to lose electrons? To become stable (its easier to lose 1 or two valence electrons than to gain 6 or 7) *Know the fact that metals tend to lose electrons. 6. Why do nonmetals tend to gain electrons? To become more stable (its easier to gain 1 or two electrons than to lose 6 or 7) *Know the fact that nonmetals tend to gain electrons. 7. What kind of bond do you have if it is between a metal and a nonmetal? Ionic (mIn) 8. What kind of bond do you have if it is between a nonmetal and a nonmetal? Covalent (CNN) 9. What kind of bond do you have if electrons are gained/lost? Ionic bond 10. What kind of bond do you have if electrons are shared? Covalent 11. What is the difference between an ionic and a covalent bond? Ionic is between metals and nonmetals covalent is only nonmetals Ionic gains and loses electrons and covalent shares electrons

Name __________________ Date ________ 12. Why do nonmetals share electrons? To become more stable. • Covalent Bonds 13. How many electrons are in one covalent bond? Two, one from each atom. 14. Why are covalently bonded compounds more stable than most un-bonded nonmetals? Covalently bonded compounds have a full valence shell 15. What is an electron dot diagram Is another way to represent an atom. It’s a model that shows the symbol and its valence electrons 16. Be able to make an electron dot diagram for the first 20 elements. *See attached a. H b. Al c. C d. P e. O f. Ne g. Be h. Li *Make sure you have the corrected chart that we cut out and taped into the notes 17. Which type of electrons (paired or unpaired) are involved in covalent bonds? Unpaired electrons are free to be shared • Chemical Bonds: Ionic 18. When elements combine do they have the same properties as they did before forming the compound? No way! 19. What is a chemical formula? Composed of symbols and subscripts indicating the number of atoms in a compound 20. What is a subscript? The small numbers written below the line that tell how many atoms of each element you have 21. When given an example, be able to identify it as either a symbol or a formula. a. H2O is a formula b. Ca is a symbol 22. What is an ion? An atom that has lost or gained electrons 23. If an atom loses an electron what will its charge be? Positive

Name __________________ Date ________ lol 24. If an atom gains an electron what will its charge be? Negative • General Skills 25. When given an example, be able to identify it as either ionic or covalent. a. KCl is ionic because it has a metal (K) and a nonmetal (Cl) b. IBr is covalent because it has a nonmetal (I) and a nonmetal (Br) • Balancing Ionic Formulas using the Criss-Cross Method 26. Know the oxidation numbers for the elements in group 1, 2, 16, and 17. a. Group 1: 1+ b. Group 2: 2+ c. Group 16: 2d. Group 17: 127. If given an element be able to tell what the oxidation number is. a. Na 1+ b. Mg 2+ c. O 2d. Br 128. Be able to balance ionic compound formulas using the criss-cross method. Metal Nonmetal Criss-Cross K Br 29. *see attached

Final Answer 30. KBr

Na

O

31. *see attached

32. Na2O

Be

S

33. *see attached

34. BeS

Li

O

35. *see attached

36. Li2O

K

S

37. *see attached

38. K2S

Li

Br

39. *see attached

40. LiBr