Lesson 17: Technicolor Atoms

Transcription

1 Lesson 17: Technicolor Atoms ChemCatalyst These drawings are models that show solid copper, solid copper chloride, and aqueous copper chloride as collections of atoms. Cu(s) Solid copper CuCl2(s) Solid copper (II) chloride CuCl2(aq) Aqueous copper (II) chloride 1. Describe each model. 2. What is similar about each model? What is different?

2 Lesson 17: Technicolor Atoms What evidence is there that certain atoms are present in a compound? By the end of today, you will be able to. conduct a flame test and use the results to determine the identity of a compound interpret evidence of the presence of certain atoms within compounds Flame test: A test used in the laboratory to look for the presence of certain metal atoms. A sample of a compound is heated in a flame, and the resulting color is noted.

3 In the Lab, reminders You will be using chemicals and fire today. Follow safety instructions. Wear safety goggles. Tie back long hair and remove dangling jewelry. Roll up long sleeves and keep clothing away from flames. Leave lab performance sheet at your station for a stamp today. Reminder sheets need to be filled out completely. Always exhibit safe behavior and clean lab stations before you leave!!

4 Lesson 17: Technicolor Atoms Notes The metal element in each chemical formula appears to be responsible for the flame colors. Only certain elements produce colorful flames. Flame test: A test used in the laboratory to look for the presence of certain metal atoms. A sample of a compound is heated in a flame, and the resulting color is noted. What are elements/compounds?

5 IV - Lesson 18: Life on the Edge ChemCatalyst 1. What do you notice about the number of spokes on the circles? 2. The spokes represent electrons. Do the spokes represent the total number of electrons? Explain your thinking. **Review: Predict the flame color produced when heating these substances. Explain your thinking. copper (II) carbonate calcium chloride

6 Lesson 17: Technicolor Atoms Sodium Atom, Na Notes Bohr s Model/ Shell model Flame colors are associated with movements of the electrons within the sodium atom.

7 Lesson 18: Life on the Edge Notes The Shell Model The surface of each sphere represents an area where an electron or a group of electrons is most likely to be found.

8 Lesson 18: Life on the Edge Notes Electron shells are the levels around the nucleus where electrons might be found. Sodium and magnesium have electrons in three electron shells.

9 Lesson 18: Life on the Edge Notes How does an element s position on the periodic table determine the arrangement of an element s electrons? G R O U P S Rows or periods

10 Lesson 18: Life on the Edge Notes There are patterns in the way electrons are arranged related to the position of the element on the periodic table. Atomic number = proton # = total # of electrons

11 Lesson 18: Life on the Edge Notes There are patterns in the way electrons are arranged related to the position of the element on the periodic table. Group # of element = # of electrons in the outermost shell I II III IV V VI VII VIII

12 Row Lesson 18: Life on the Edge Notes Row of element = # of electron shells

13 Lesson 18: Life on the Edge Notes The first shell can hold up to 2 electrons. The second shell can hold up to 8 electrons

14 Lesson 18: Life on the Edge Notes Draw an atom with 3 shells and 2 electrons in its outermost shell. What element is this?

15 Lesson 18: Life on the Edge Notes The electrons in the outermost shell are called valence electrons. The electrons in the inner shells are called core electrons. Valence electrons Core electrons

16 IV-Lesson 19: Noble Gas Envy ChemCatalyst Chemists have found that metal atoms transfer electrons to nonmetal atoms when they form compounds. Examine the shell model showing how a lithium atom might transfer an electron to a fluorine atom. 1. What effect does this electron transfer have on the charge of each atom? 2. What element does each atom resemble after the electron has been transferred?

17 Lesson 18: Life on the Edge Check-In Provide each piece of information for element 34. a. The element s name and symbol. b. The total number of electrons in an atom of this element. c. The number of core electrons in an atom of this element. d. The number of valence electrons. e. The group number for this element. f. The names of other elements with the same number of valence electrons.

18 IV-Lesson 19: Noble Gas Envy Notes What happens when atoms form ions? Ion: An atom that has acquired a net electric charge by gaining or losing one or more electrons. When electrons are removed from or added to an atom, the rest of the atom stays the same.

19 IV-Lesson 19: Noble Gas Envy Activity 8 1) Number the cards1-20 then ) Shuffle the cards, then deal to your team. 3) The number of the cards you get is the atomic number. Create cards like the ones shown.

20 IV-Lesson 20: Getting Connected ChemCatalyst Over Weekend: Get caught up with textbook questions! Metal elements combine with the nonmetal element chlorine, Cl, to form compounds. The formulas are given in the tables. Element Compound Element Compound Element Compound Na NaCl Mg MgCl 2 Ne none K KCl Ca CaCl 2 Ar none 1. Compare the three tables. What do you notice? (check periodic table) 2. Predict the formula of a compound formed between lithium, Li, and chlorine, Cl. Which table would you put it in?

21 IV-Lesson 19: Noble Gas Envy Notes The Ion Card Table

22 IV-Lesson 19: Noble Gas Envy Notes Electron arrangements of atoms in ionic compounds resemble noble gases. Atoms tend to lose or gain electrons to attain the electron arrangement of a noble gas.

23 1e- +1 IV-Lesson 19: Noble Gas Envy Add Info to your Table 2e- 3e- 4e- 5e- 6e- 7e- Key: # valence electrons cation charge anion charge 8e- 0

24 IV-Lesson 19: Noble Gas Envy Check-In 1. Draw a shell model for calcium, Ca, showing the arrangement of its electrons. 2. What would have to happen for an atom of calcium to have an electron arrangement like that of a noble gas? Explain.

25 IV-Lesson 19: Noble Gas Envy Wrap-Up How is chemical stability related to the arrangements of electrons in atoms? When atoms gain or lose electrons, they form ions. Ions are atoms that carry a net positive or net negative charge. When atoms lose electrons, they have a positive charge and are called cations. When atoms gain electrons, they have a negative charge and are called anions. Ions have electron arrangements resembling those of the noble gas atoms.

26 IV-Lesson 20: Getting Connected ChemCatalyst Over Weekend: Get caught up with textbook questions! Metal elements combine with the nonmetal element chlorine, Cl, to form compounds. The formulas are given in the tables. Element Compound Element Compound Element Compound Na NaCl Mg MgCl 2 Ne none K KCl Ca CaCl 2 Ar none 1. Compare the three tables. What do you notice? (check periodic table) 2. Predict the formula of a compound formed between lithium, Li, and chlorine, Cl. Which table would you put it in?

27 IV-Lesson 20: Getting Connected Notes How can valence electrons be used to predict chemical formulas? Metal atoms and nonmetal atoms combine to form ionic compounds. metals: non-metal: Examples: NaCl, MgCl 2

28 IV-Lesson 20: Getting Connected Notes Combine magnesium, Mg, and chlorine, Cl, into an ionic compound so that each ion resembles a noble gas. Cl Mg Cl

29 IV-Lesson 20: Getting Connected Notes Mg 2+ + Cl + Cl produces MgCl 2 with zero charge.

30 IV-Lesson 20: Getting Connected Notes How can valence electrons be used to predict chemical formulas? In ionic compounds the metal is considered the cation and the nonmetal is considered the anion. + - Example: NaCl, MgCl 2 Mg 2+ is the, Cl - is the. Na + is the, Cl - is the.

31 IV-Lesson 20: Getting Connected Notes How can valence electrons be used to predict chemical formulas? Metal atoms and nonmetal atoms combine in ratios that result in a total of 8 or a multiple of 8 valence electrons.

32 IV-Lesson 20: Getting Connected Notes How can valence electrons be used to predict chemical formulas? The charges on the cations and anions in ionic compounds add to zero. Examples: Na + and Cl - form NaCl ( Na + + Cl - = 0 ) Mg 2+ and Cl - form MgCl 2 ( Mg 2+ + Cl - + Cl - = 0)

33 IV-Lesson 19: Noble Gas Envy Notes On a full page, make the following table. Draw the ions and compounds. F O N Li Mg Chemical Formula Al Chemical Formula Al 2 O 3

34 IV-Lesson 20: Getting Connected Check-In Use your periodic table to write the correct chemical formula of 3 ionic compounds formed from the following elements: Sr K S H Br

35 Wrap Up How can valence electrons be used to predict chemical formulas? Metal atoms and nonmetal atoms combine to form ionic compounds. In ionic compounds, the metal is considered a cation, and the nonmetal is considered an anion. The charges on the cations and the anions in ionic compounds sum to 0. Metal atoms and nonmetal atoms usually combine in ratios that result in a total of eight valence electrons or a multiple of eight valence electrons.

36 Check-in What elements will combine with strontium, Sr, in a 1:1 ratio? Explain your thinking.

37 IV-21: Salty Eights ChemCatalyst Reminder: Our focus is valence electrons 1. List the ionic compounds you can make with 2 cards, using 2 different elements. 2. List the ionic compounds you can make with 3 cards and only 2 different elements. 3. What rule must all these compounds satisfy?

38 IV-Lesson 20: Getting Connected Work Check Chemical Formulas of Ionic Compounds Example Number of valence electrons for the metal Number of valence electrons for the nonmetal Total number of valence electrons Total positive charge Total negative charge Total charge NaF MgO MgCl ( 1) 0 K 2 Se (+1) 2 0 AlN Al 2 O (+3) 3( 2) 0 AlF ( 1) 0

39 IV-Lesson 20: Getting Connected Notes Naming ionic compounds: Metal then non-metal. Change the ending of the non-metal to ide. Examples: Na 2 O sodium oxide MgCl 2 magnesium chloride

40 IV-21: Salty Eights The Game Predicting chemical formulas & naming ionic compounds.

41 IV-21: Salty Eights Scoring the Game Rules on Back of handout 5 points for every noble gas 10 points for every compound made out of two cards 40 points for every compound made out of three cards 70 points for every compound made out of four cards 100 points for every compound made out of five cards 20 points for going out first

42 IV-21: Salty Eights Notes In general, atoms come together to form an ionic compound if the number of valence electrons totals 8 or a multiple of 8.

43 IV-21: Salty Eights Notes Writing correct chemical formulas is a matter of keeping track of exactly how many atoms come together to make a compound.

44 IV-21: Salty Eights Wrap-Up How can you predict chemical formulas and name ionic compounds? Ionic compounds tend to form from atoms that together have a total of 8 (or a multiple of 8) electrons in their outermost (valence) shells. Noble gases already have eight valence electrons and don t combine with other elements to make new compounds. They are already highly stable.

45 IV-21: Salty Eights Check-In Which of these compounds are likely to form? a. Na 2 S b. K 2 Mg c. AlBr 2 d. Na 3 N e. OCl f. CaO

46 IV-22 Isn t it Ionic? Polyatomic Ions ChemCatalyst The cards show a sodium ion and three polyatomic ions. 1. What do you think a polyatomic ion is? 2. Name three compounds formed between sodium ions and each of the three polyatomic ions. Use the rule of zero charge to write the compounds formulas.

47 IV-22 Isn t it Ionic? Review Ionic compound: An ionic compound is a compound composed of positive and negative ions, formed when metal and nonmetal atoms combine.

48 IV-22 Isn t it Ionic? Notes Polyatomic Ions ~ many atom ion Polyatomic ion: Ions composed of several different atoms. These atoms stay together as a group. The charge is shared amongst all of the atoms. Most polyatomic ions are anions.

49 IV-22 Isn t it Ionic? Notes The rule of zero charge can be used to predict the formulas of compounds that contain polyatomic ions.

50 IV-22 Isn t it Ionic? Notes Polyatomic Ions Compounds containing polyatomic ions have their own unique naming guidelines. Polyatomic ion OH NO 3 CO 2 3 SO 2 4 NH + 4 Name hydroxide nitrate carbonate sulfate ammonium

51 IV-22 Isn t it Ionic? Notes What is a polyatomic ion? Polyatomic ions are ions composed of a group of atoms. The charge is shared by all the atoms. To write the formula of an ionic compound that contains polyatomic ions, use the rule of zero charge. When naming compounds containing polyatomic ions, simply insert the name of the ion.

52 IV-22 Isn t it Ionic? Check-In 1. What is the name of the compound Be(NO 3 ) 2? 2. What ions are present in this compound, and what are the charges on the ions?

53 IV23: Alchemy of Paint Transition Metal Chemistry Transition Metals tend to be brightly colored common found as pigments Ex: Blue cobalt blue cobalt (II) oxide To determine the charges on transition metal cations: 1. Determine the ion charge that you do know 2. Apply the rule of zero charge FeO Cation: Anion:

54 Transition Metal Compounds Practice In your binder Chemical Name Chemical Formula Cation Anion Cobalt (II) oxide Fe 2 O 3 Cr 3+ O 2- Manganese (IV) dioxide MnO 2 Copper (I) oxide Silver sulfide Ag 2 S Fe(NO 3 ) 3 Copper (II) carbonate Cu 2+ Most transition metals can form several ions with different charges

55 IV 24: Shell Game Electron Configurations Goals describe the structure of an atom in terms of electron shells and subshells use the periodic table to determine the electron arrangement in an atom and to write electron configurations explain the organization of the periodic table in terms of the arrangements of electrons in subshells

56 IV 24: Shell Game Electron Configurations ChemCatalyst These drawings show two different ways to represent the arrangement of the electrons in atoms of the element calcium, Ca. 1. Name at least two differences in the drawings. 2. Name at least two similarities in the drawings.

57 IV 24: Shell Game Electron Configurations Notes The electron shells in the shell model of an atom are divided into subshells (except for the first shell, n=1). Shell Number of electrons in the shell Subshell Number of electrons in the subshell n = 1 2 1s 2 n = 2 8 n = 3 18 n = s 2p 3s 3p 3d 4s 4p 4d 4f

58 IV 24: Shell Game Electron Configurations Notes The periodic table is organized in subshell blocks.

59 IV 24: Shell Game Electron Configurations Notes No chemcatalyst today Electron configuration: A shorthand way to keep track of all the electrons in an atom of an element for all the subshells that have electrons. 1s 2 2s 2 2p 6 Shell # Subshell Letter # of electrons in the shell What element does this electron configuration code for??

60 IV 24: Shell Game Electron Configurations Notes The order of filling subshells does not always correspond to the numerical order of the subshells. (4s 2 3d 10 ) The elements in the different subshell blocks have related properties. Chemists keep track of electrons and the subshells they are in by writing electron configurations.

61 IV 24: Shell Game Electron Configurations Check-In Identify the element with this electron configuration: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 3

62 Wrap Up What does the periodic table indicate about the arrangements of electrons? Each electron shell in the shell model, except for n = 1, is divided into subshells. Each subshell can hold a specific maximum number of electrons. The periodic table can assist you in figuring out the placement of electrons in subshells. Chemists keep track of electrons and the subshells they are in by writing electron configurations.