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Ch 7 PowerPoint Notes Section 7.1 - Ions OBJECTIVES: OBJECTIVES: Determine the number of valence electrons in an atom of a representative element. Determine.

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Presentation on theme: "Ch 7 PowerPoint Notes Section 7.1 - Ions OBJECTIVES: OBJECTIVES: Determine the number of valence electrons in an atom of a representative element. Determine."— Presentation transcript:

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2 Ch 7 PowerPoint Notes

3 Section 7.1 - Ions OBJECTIVES: OBJECTIVES: Determine the number of valence electrons in an atom of a representative element. Determine the number of valence electrons in an atom of a representative element.

4 Section 7.1 - Ions OBJECTIVES: OBJECTIVES: Explain how the octet rule applies to atoms of metallic and nonmetallic elements. Explain how the octet rule applies to atoms of metallic and nonmetallic elements.

5 Section 7.1 - Ions OBJECTIVES: OBJECTIVES: Describe how cations and anions form. Describe how cations and anions form.

6 Why do some elements react to form compounds and others do not? Is there any way to predict if atoms might react with each other? Is there any way to predict what chemical formulas might be formed?

7 Ionic and Metallic Bonding Na 1+, Na +1 or Na + = cation, missing 1 e- O 2- = anion, gained 2 e- (the number is the charge on ion, not # of e- gained or lost,, i.e., +1 means 1 electron lost, not 1 gained.)

8 Ion definitions Valence electrons: Outermost electrons. The s and p electrons in the outer energy level. The highest occupied energy level. Valence electrons: Outermost electrons. The s and p electrons in the outer energy level. The highest occupied energy level. Core electrons: are those in the energy levels below. Core electrons: are those in the energy levels below. Ion: An atom that has lost or gained an electron. Ions have a + or - charge. Ion: An atom that has lost or gained an electron. Ions have a + or - charge. (Atoms are always neutral, # of p+ = # of e - ) (Atoms are always neutral, # of p+ = # of e - ) Cation: Positive Ion or metals, gained e -. Cation: Positive Ion or metals, gained e -. Anion: Negative Ion or non-metals, Lost e -. Anion: Negative Ion or non-metals, Lost e -.

9 Valence Electrons are…? The electrons responsible for the chemical properties of atoms, and are those in the outer energy level. The electrons responsible for the chemical properties of atoms, and are those in the outer energy level. Valence electrons - The s and p electrons in the outer energy level Valence electrons - The s and p electrons in the outer energy level the highest occupied energy level the highest occupied energy level Core electrons – are those in the energy levels below. Core electrons – are those in the energy levels below.

10 Keeping Track of Electrons Atoms in the same column (group)... Atoms in the same column (group)... 1) Have the same outer electron configuration. 2) Have the same valence electrons. The number of valence electrons are easily determined. It is the group number for representative. The number of valence electrons are easily determined. It is the group number for representative. Group 2A: Be, Mg, Ca, etc. Group 2A: Be, Mg, Ca, etc. have 2 valence electrons have 2 valence electrons Group 8A, Noble gases has 8. Group 8A, Noble gases has 8.

11 Electron Dot diagrams are… DEF: Shows the 8 valence electrons as dot pairs around the chemical symbol. DEF: Shows the 8 valence electrons as dot pairs around the chemical symbol. A way of showing & keeping track A way of showing & keeping track of valence electrons. of valence electrons. How to write them? How to write them? Write the symbol - it represents the nucleus and inner (core) electrons Write the symbol - it represents the nucleus and inner (core) electrons Put one dot for each valence electron (8 maximum) Put one dot for each valence electron (8 maximum) They don’t pair up until they have to (Hund’s rule). Do 4 singles before pairs. They don’t pair up until they have to (Hund’s rule). Do 4 singles before pairs. X

12 Electron Dot diagrams Single dots can be on any side. 1A 2A 3A4A 5A 6A 7A 8A

13 Valence e- highest electron energy level of an atom (ns np…where n is the same number) Nitrogen 1s 2 2s 2 2p 3 5 Valence e-

14 e- dot structures show only valence e- (single per side/then pair up) 2 dots Mg –[Ne]3s 2 3p 0

15 Need to Memorize!! EASY!

16 valence e- determine the chemical properties of an element Alkali metals (1 ve-) - ns 1 np 0

17 Remember s, p, d, f blocks 12345671234567 12345671234567 S p 1S 1 1S 2 2S 1 2S 2 3S 1 3S 2 2p 1 2p 2 2p 3 2p 4 2p 5 2p 6

18 Write the e dot structures O = 1s 2 2s 2 2p 4 Ne = Na =

19 Write the e dot structures O = 1s 2 2s 2 2p 4 Ne = 1s 2 2s 2 2p 6 Na = 1s 2 2s 2 2p 6 3s 1 3p

20 e dot structures – show valence e- as dots O = 1s 2 2s 2 2p 4 Ne = 1s 2 2s 2 2p 6 Na = 1s 2 2s 2 2p 6 3s 1 3p

21 octet rule – ions tend to have pseudo noble gas configuration (8 valence e-) full s and p orbitals

22 Formation of Cations Metals lose electrons to attain a noble gas configuration. Metals lose electrons to attain a noble gas configuration. They make positive ions (cations) They make positive ions (cations) If we look at the electron configuration, it makes sense to lose electrons: If we look at the electron configuration, it makes sense to lose electrons: Na 1s 2 2s 2 2p 6 3s 1 1 valence electron Na 1s 2 2s 2 2p 6 3s 1 1 valence electron Na 1+ 1s 2 2s 2 2p 6 This is a noble gas configuration with 8 electrons in the outer level. Na 1+ 1s 2 2s 2 2p 6 This is a noble gas configuration with 8 electrons in the outer level.

23 Electron Dots For Cations Metals will have few valence electrons (usually 3 or less); calcium has only 2 valence electrons Metals will have few valence electrons (usually 3 or less); calcium has only 2 valence electrons Ca

24 Electron Dots For Cations Metals will have few valence electrons Metals will have few valence electrons Metals will lose the valence electrons Metals will lose the valence electrons Ca

25 Electron Dots For Cations Metals will have few valence electrons Metals will have few valence electrons Metals will lose the valence electrons Metals will lose the valence electrons Forming positive ions Forming positive ions Ca 2+ NO DOTS are now shown for the cation. This is named the “calcium ion”.

26 Electron Configurations: Anions Nonmetals gain electrons to attain noble gas configuration. Nonmetals gain electrons to attain noble gas configuration. They make negative ions (anions) They make negative ions (anions) S = 1s 2 2s 2 2p 6 3s 2 3p 4 = 6 valence electrons S = 1s 2 2s 2 2p 6 3s 2 3p 4 = 6 valence electrons S 2- = 1s 2 2s 2 2p 6 3s 2 3p 6 = noble gas configuration. S 2- = 1s 2 2s 2 2p 6 3s 2 3p 6 = noble gas configuration. Halide ions are ions from chlorine or other halogens that gain electrons Halide ions are ions from chlorine or other halogens that gain electrons

27 Electron Dots For Anions Nonmetals will have many valence electrons (usually 5 or more) Nonmetals will have many valence electrons (usually 5 or more) They will gain electrons to fill outer shell. They will gain electrons to fill outer shell. P 3- (This is called the “phosphide ion”, and should show dots)

28 Stable Electron Configurations All atoms react to try and achieve a noble gas configuration. All atoms react to try and achieve a noble gas configuration. Noble gases have 2 s and 6 p electrons. Noble gases have 2 s and 6 p electrons. 8 valence electrons = already stable! 8 valence electrons = already stable! This is the octet rule (8 in the outer level is particularly stable). This is the octet rule (8 in the outer level is particularly stable). Ar

29 ATOM Na = 1s 2 2s 2 2p 6 3s 1 3p 0 ION Na +1 = 1s 2 2s 2 2p 6

30 a. What is the charge of an e-? b. What is the e- config for N 3- ion? c. How many e- does (B) have? d. how many valence e- does (B) have?

31 Common IONIC CHARGES OF REPRESENTATIVE ELEMENTS Add to periodic table 1+12+213+31415-316-217 LiNaKRbCsBeMgCaSrBa AlNPAsOSSeFClBrI

32 Why don’t the noble gases form ions?

33 When writing S 2-, what does the 2- indicate? Does this ion have more or less e than the original atom?

34 Section 7.2 Ionic Bonds and Ionic Compounds OBJECTIVES: OBJECTIVES: Explain the electrical charge of an ionic compound. Explain the electrical charge of an ionic compound.

35 Section 7.2 Ionic Bonds and Ionic Compounds OBJECTIVES: OBJECTIVES: Describe three properties of ionic compounds. Describe three properties of ionic compounds.

36 Ionic Compounds – compounds formed from cations and anions Usually a metal and a nonmetal (the charges always cancel) Na +, Cl - = NaCl

37 Ionic Bonding Anions and cations are held together by opposite charges (+ and -) Anions and cations are held together by opposite charges (+ and -) Ionic compounds are called salts. Ionic compounds are called salts. Simplest ratio of elements in an ionic compound is called the formula unit. Simplest ratio of elements in an ionic compound is called the formula unit. The bond is formed through the transfer of electrons (lose and gain) The bond is formed through the transfer of electrons (lose and gain) Electrons are transferred to achieve noble gas configuration (Octet Rule). Electrons are transferred to achieve noble gas configuration (Octet Rule).

38 Ionic Compounds 1)Also called SALTS 2)Made from: a CATION with an ANION (or literally from a metal combining with a nonmetal)

39 Ionic Bonding NaCl The metal (sodium) tends to lose its one electron from the outer level. The nonmetal (chlorine) needs to gain one more to fill its outer level, and will accept the one electron that sodium is going to lose.

40 Ionic Bonding Na + Cl - Note: Remember that NO DOTS are now shown for the cation!

41 Chemical formula = number of atoms in a formula unit of an ionic compound (and not the charges on the ions) Formula unit = NaCl

42 Ionic Bonding All the electrons must be accounted for, and each atom will have a noble gas configuration (which is stable). All the electrons must be accounted for, and each atom will have a noble gas configuration (which is stable). CaP Lets do an example by combining calcium and phosphorus:

43 Ionic Bonding CaP

44 Ionic Bonding Ca 2+ P

45 Ionic Bonding Ca 2+ P Ca

46 Ionic Bonding Ca 2+ P 3- Ca

47 Ionic Bonding Ca 2+ P 3- Ca P

48 Ionic Bonding Ca 2+ P 3- Ca 2+ P

49 Ionic Bonding Ca 2+ P 3- Ca 2+ P Ca

50 Ionic Bonding Ca 2+ P 3- Ca 2+ P Ca

51 Ionic Bonding Ca 2+ P 3- Ca 2+ P 3- Ca 2+

52 Ionic Bonding = Ca 3 P 2 Formula Unit This is a chemical formula, which shows the kinds and numbers of atoms in the smallest representative particle of the substance. For an ionic compound, the smallest representative particle is called a: Formula Unit

53 Chemical formula = number of atoms in a formula unit of an ionic compound (and not the charges on the ions) Formula unit = NaCl

54 Ionic compounds are usually brittle solids at room temperature, with repeating internal 3-D crystal patterns, that have high melting points

55 Ionic bonds – electrostatic force that holds compound together

56 What number of each ion do you need to make an ionic compound? Na, F Na, S Al, N

57 What number of each ion do you need to make an ionic compound? Na, FNaF Na, SNa 2 S Al, NAlN

58 Metal bonds valence electrons of metal atoms can be modeled as a sea of electrons Metallic bonds = free-floating valence electrons attracted to the positively charged metal ions

59 Alloys are mixtures composed of two or more elements, at least one of which is a metal

60 Quick review questions Can have everyone stand up and answers following q’s to sit down. Can have everyone stand up and answers following q’s to sit down.

61 An ionic compound is usually formed between a metal and a __?

62 How many dots around a sodium atom?

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64 What is the charge on a sodium atom?

65 What is the charge on a sodium ion?

66 What are some ionic compounds formed with sodium?

67 What is the charge on an aluminum ion?

68 What are some ionic compounds formed with Aluminum?

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