2. Section 7-1 Section 7.1 Ion Formation Define a chemical bond. octet rule: atoms tend to gain, lose, or share electrons in order to acquire eight valence electrons chemical bond cation anion Describe the formation of positive and negative ions. Relate ion formation to electron configuration. Ions are formed when atoms gain or lose valence electrons to achieve a stable octet electron configuration.

3. Section 7-1 Valence Electrons and Chemical Bonds A chemical bond is the force that holds two atoms together.chemical bond Chemical bonds form by the attraction between the positive nucleus of one atom and the negative electrons of another atom. They can also form by the attraction between positive and negative ions.

4. Section 7-1 Valence Electrons and Chemical Bonds (cont.) Atom’s try to form an octet — the stable arrangement of eight valence electrons in the outer energy level— by gaining or losing valence electrons.

5. Noble gases are unreactive because they have a filled valence shell. –If sodium were to lose one valence electron, its electron configuration would be like neon. –They would both have 10 electrons –The number of protons, however, would still be different. Na = 11 protons Ne = 10 protons

6. Ion Formation Elements want to obtain the same number of electrons as the closest Noble Gas SO… –Metals and Hydrogen tend to lose electrons to achieve the same number of electrons as a noble gas (POSITIVE IONS = CATIONS) –Nonmetals tend to gain electrons to achieve the same number of electrons as a noble gas (NEGATIVE IONS = ANIONS)

7. Section 7-1 Positive Ion Formation A positively charged ion is called a cation.cation The number of Protons does not change *Positive ions form when an atom loses one or more valence electrons.

8. Section 7-1 Positive Ion Formation (cont.) Metals are reactive because they lose valence electrons easily.

9. Section 7-1 Positive Ion Formation (cont.) Transition metals commonly form 2+ or 3+ ions, but can form greater than 3+ ions. Other relatively stable electron arrangements are referred to as pseudo-noble gas configurations.

10. Section 7-1 Negative Ion Formation An anion is a negatively charged ion.anion Negative ions form when an atom gains one or more valence electrons. The number of Protons does not change

11. Section 7-1 Negative Ion Formation (cont.) Nonmetal ions gain the number of electrons required to fill an octet. Some nonmetals can gain or lose electrons to complete an octet.

12. Group 1 elements = +1 ions Group 2 elements = +2 ions Groups 3-12 elements = more than one charge (all positive) typically +2,+3,+4 Group 13 elements = +3 ions (B, Al, Ga, In and Tl)

13. Group 14 elements can be +4, -4, or 0. C and Si usually 0, Ge, Sn, and Pb +2 or +4 Group 15 elements of N, P, and As are -3 ions, Sb and Bi are usually (+ ions) Group 16 elements of O, S, Se, Te are -2 ions Group 17 elements = -1 ions all of them Group 18 element = 0 charge = Noble gases (not reactive)

15. Section 7-3 Section 7.3 Names and Formulas for Ionic Compounds Relate a formula unit of an ionic compound to its composition. nonmetal: an element that is generally a gas or a dull, brittle solid and is a poor conductor of heat and electricity Write formulas for ionic compounds and oxyanions. Apply naming conventions to ionic compounds and oxyanions.

16. Section 7-3 Section 7.3 Names and Formulas for Ionic Compounds (cont.) formula unit monatomic ion oxidation number polyatomic ion oxyanion In written names and formulas for ionic compounds, the cation appears first, followed by the anion.

17. Section 7-3 Formulas for Ionic Compounds (cont.) A formula unit represents the simplest ratio of the ions involved.formula unit Monatomic ions are one-atom ions.Monatomic ions Negative monatomic ions always end with –ide Example: oxygen becomes oxide as an anion Positive monatomic ions keep their name Example: sodium stays sodium as a cation

18. Section 7-3 Formulas for Ionic Compounds (cont.) Oxidation number, or oxidation state, is the charge of a monatomic ion.Oxidation number

19. Section 7-3 Formulas for Ionic Compounds (cont.) Polyatomic ions are ions made up of more than one atom.Polyatomic ions Never change subscripts of polyatomic ions, place in parentheses and write the appropriate subscript outside the parentheses.

20. Write the symbol for each ion including the charge, Cation first then Anion. Overall charge must equal zero. –If charges cancel, just write symbols. –If not, use subscripts to balance charges. –Subscripts represent the number of ions of each element in an ionic compound. Use parentheses to show more than one polyatomic ion. Formulas for Ionic Compounds

21. Ionic Compound Formation Example: Aluminum sulfide 1. Write the formulas for the cation and anion, including CHARGES! Al 3+ S 2- 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! 23

22. Example: Zinc hydroxide 1. Write the formulas for the cation and anion, including CHARGES! Zn 2+ OH - 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! ( ) 2

23. Example: Magnesium carbonate 1. Write the formulas for the cation and anion, including CHARGES! Mg 2+ CO 3 2- 2. Check to see if charges are balanced. They are balanced!

24. Example: Iron(III) chloride 1. Write the formulas for the cation and anion, including CHARGES! Fe 3+ Cl - 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! 3

25. potassium chloride magnesium nitrate copper(II) chloride –K + + Cl  –Mg 2+ + NO 3  –Cu 2+ + Cl   KCl  Mg(NO 3 ) 2  CuCl 2 Ionic Compound Formation

26. Ionic Compound Nomenclature (naming) Write the name of the Cation followed by the name of the Anion Cations keep their original name Change ending of monatomic anions to -ide. Polyatomic ions have special names. (learn them) Metals with multiple Charges (oxidation numbers) have Roman Numerals that indicate the positive charge on the ion

27. Section 7-3 Names for Ions and Ionic Compounds An oxyanion is a polyatomic ion composed of an element (usually a non- metal), bonded to one or more oxygen atoms.oxyanion

28. Section 7-3 Names for Ions and Ionic Compounds (cont.)

29. Section 7-3 Names for Ions and Ionic Compounds (cont.)

30. NaBr K 2 CO 3 FeCl 3 –sodium bromide –potassium carbonate –iron(III) chloride Examples

31. Section 8.2 Naming Molecules Translate molecular formulas into binary molecular compound names. oxyanion: a polyatomic ion in which an element (usually a nonmetal) is bonded to one or more oxygen atoms oxyacid Name acidic solutions. Specific rules are used when naming binary molecular compounds, binary acids, and oxyacids.

32. Why do atoms bond? (cont.) The chemical bond that results from sharing electrons is a covalent bond.covalent bond A molecule is formed when two or more nonmetal atoms bond.molecule Gaining or losing electrons makes atoms more stable by forming ions with noble-gas electron configurations. (octet) Sharing valence electrons with other atoms also results in noble-gas electron configurations.

33. Shared electrons are considered to be part of the outer energy level of all the atoms that share it. This type of bonding usually occurs between elements near each other on the periodic table. Most of this type of bonding is done with nonmentals.

34. Molecular Nomenclature (Naming) Prefix System (binary compounds) 1.Less electronegative atom comes first. 2.The first element is always named first using the entire element name. 3.Add prefixes to indicate the subscripts of each atom. Omit the mono- prefix on first element. 4.Change the ending of the second element to -ide.

35. PREFIX mono- di- tri- tetra- penta- hexa- hepta- octa- nona- deca- NUMBER 1 2 3 4 5 6 7 8 9 10 Molecular Nomenclature

36. Name the following: P 2 O 5 –Name the two elements: Phosphorus and Oxygen For the second element, the name is changed to oxide. Add the prefixes to show the number of atoms. –Diphosphorus pentoxide

37. Exception to the prefixes in table 8.3: –The first element never uses the mono prefix –If using a prefix would cause two consecutive vowels, one of the them is often dropped to avoid a difficult pronunciation. CO is monoxide NOT monooxide.

38. CCl 4 N 2 O SF 6 –carbon tetrachloride –dinitrogen monoxide –sulfur hexafluoride Molecular Nomenclature

39. arsenic trichloride dinitrogen pentoxide tetraphosphorus decoxide –AsCl 3 –N2O5–N2O5 –P 4 O 10 Molecular Nomenclature

40. NOF Cl Br I H Molecular Nomenclature The Seven Diatomic Elements, exist naturally as 2 atom molecules H 2 N 2 O 2 F 2 Cl 2 Br 2 I 2

41. Naming Binary Molecular Compounds (cont.) Many compounds were discovered and given common names long before the present naming system was developed. (water H 2 O, ammonia NH 3, hydrazine N 2 H 4, and nitric oxide NO are examples). These compounds are generally known by their common names instead of their scientific ones. What would their scientific names be?

42. Acids –Compounds that form [H + ] in Solution (water). –Formulas begin with ‘H’. Examples: –HCl – hydrochloric acid –HNO 3 – nitric acid –H 2 SO 3 – sulfurous acid Naming Acids

43. Acid Nomenclature Anion Ending -ide -ate -ite Acid Name –Hydro-(stem)-ic acid –(stem)-ic acid –(stem)-ous acid

44. HBr H 2 CO 3 H 2 SO 3 –Br ends in -ide – CO 3 ends in -ate –SO 3 ends in -ite  hydrobromic acid  carbonic acid  sulfurous acid Acid Nomenclature

45. hydrofluoric acid sulfuric acid nitrous acid –Fluoride –Sulfate –Nitrite  HF  H 2 SO 4  HNO 2  H + F -  H + SO 4 2-  H + NO 2 - Acid Nomenclature

46. Naming Acids (cont.) The second word is always acid. Notice that hydrogen is not part of the name.

47. Naming Acids (cont.) An acid, whether a binary acid or an oxyacid, can have a common name in addition to its compound name.