Lesson 17 Technicolor Atoms Flame tests Chem Catalyst

Lesson 17: Technicolor Atoms Flame tests

Chem. Catalyst These drawings are models that show solid copper, solid copper chloride, and aqueous copper chloride as collections of atoms. 1. Describe each model. 2. What is similar about each model? What is different?

Key Question What evidence is there that certain atoms are present in a compound?

You will be able to: • Conduct a flame test and use the results to determine identity of a compound • Interpret evidence of the presence of certain atoms within compounds

Prepare for the Lab Work in Lab groups Safety Instructions: You will be working with flames and chemicals today. Wear safety goggles Roll up long sleeves, tuck in loose clothing, and tie back long hair. Know the location of the eye wash, fire blanket and fire extinguisher

Discussion 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.

Discussion Notes (cont. ) Elements and compounds are collections of atoms. The only way to change one atom into another is to change the nucleus through a nuclear reaction.

Discussion Notes (cont. ) The illustration indicates that the flame colors are associated with movements of the electrons within the sodium atom. Bohr’s model of the atom came directly from evidence similar to that produced in class today.

Wrap Up What evidence is there that certain atoms are present in a compound? • Many metal atoms produce a characteristic colored flame when compounds containing those atoms are heated in a flame. • Flame tests are evidence that elements and compounds are collections of atoms.

Check-in Predict the flame colors produced when heating these substances. Explain your thinking. copper (II) carbonate calcium chloride

Lesson 18: Life on the Edge Valence and Core Electrons

Chem. Catalyst. 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.

Key Question Why do elements in the same group in the periodic table have similar properties?

You will be able to: • Create a shell model diagram of an atom, placing the correct number of electrons in the correct shell • Explain the difference between a valence electron and a core electron • Describe the patterns in the periodic table associated with electron arrangements

Prepare for the Activity Work in groups. The models shown are simplified 2 -D and 3 -D models. Electron shells are the levels around the nucleus where electrons can be found. These levels are represented on models by spheres or circles.

Discussion Notes The atomic number of an element is the same as the total number of electrons. The period (row) number of the element is the same number of electron shells. For main-group elements, the group number of the element is the same as the number of electrons in the outermost shell.

Discussion Notes (cont. ) The outermost electron shell is referred to as the valence shell. The arrangement of electrons in their shell is highly predictable. The number of core electrons also exhibit patterns each row of the periodic table.

Discussion Notes (cont. ) Valence Shell: The outermost electron shell in an atom. Valence electrons: The electrons located in the outermost electron shell of an atom. Core electrons: All other electrons in an atom besides the valence electrons.

Wrap Up Why do elements in the same group in the periodic table have similar properties? • Electrons occupy distinct areas around the nucleus called electron shells. The arrangement of electrons in these shells is highly predictable • For main group elements, elements in the same group number have the same number of valence electrons

Wrap Up (cont. ) • The number of valence electrons increases across a period • The number of shells and the number of core electrons increase as you go down a group.

Check-in Provide each piece of information for element 34 a. The element 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.

Lesson 19: Noble Gas Envy Ions

Chem. Catalyst 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?

Key Question How is chemical stability related to the arrangement of electrons in atoms?

You will be able to: • • • Explain that an ion is formed when an atom loses or gains electrons and state the difference between a cation and an anion Determine the charge on an ion based on an atom’s placement in the periodic table Explain the relationship between ion charge and valence electrons

Prepare for the Activity Work in groups of 8 Focus on taking an inventory of protons and electrons in each atom Ion – An atom(or group of atoms) that has a positive or negative charge because it has lost or gained electrons.

Discussion Notes The table of arranged ion cards shows that the charges on ions are quite predictable. When electrons are removed from or added to an atom, the rest of the atom stays the same. The charge on an ion is noted with a superscript.

Discussion Notes (cont. ) Cation – An ion with a net positive charge. Usually these are formed from metal atoms. Anion – An ion with a net negative charge. Usually these are formed from nonmetal atoms. The ions formed from transition elements are exceptions to these simple rules.

Discussion Notes (cont. ) After an electron transfer occurs, the electron arrangements of the resulting ions look surprisingly like the electron arrangements of noble gases. Atoms tend to lose or gain electrons to attain the electron arrangement of a noble gas.

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

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

Lesson 20: Getting Connected Ionic Compounds

Chem. Catalyst Metal elements combine with the nonmetal element chlorine, Cl, to form compounds, the formulas are given in the tables. 1. Compare three tables. What do you notice? 2. Predict the formula of a compound formed between lithium, Li, and chlorine, Cl. Which table would you put it in?

Key Question How can valence electrons be used to predict chemical formulas?

You will be able to: • • Predict the chemical formulas of compounds that will form between metal and nonmetal atoms Explain how an ionic compound forms and determine whether it follows the rule of zero charge.

Prepare for the Activity Work in groups. You should each have a copy of the periodic table. Ionic Compound – An ionic compound is a compound composed of positive and negative ions, formed when metal and nonmetal atoms combine.

Discussion Notes Metal and nonmetal elements combine to form ionic compounds. The electron arrangements of the cations and anions resemble the arrangements of a noble gas atom.

Discussion Notes (cont. ) The rule of zero charge can be used to determine the chemical formulas of ionic compounds. Rule of Zero Charge - In an ionic compound, the positive charges on the metal cations and the negative charges on the nonmetal anions sum to 0. The number of electrons associated with the atoms of an ionic compound generally totals 8 or a multiple of 8

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.

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

Lesson 21: Salty Eights Formulas for Ionic Compounds

Chem. Catalyst Find these cards in your Salty Eights card deck. 1. List the ionic compounds you can make with pairs of cards, using two different elements. 2. List the ionic compounds you can make with three cards and only two different elements. 3. What rule must all these compounds satisfy?

Key Question How can you predict chemical formulas and name ionic compounds?

You will be able to: • Use valence electrons to predict ionic compounds • Develop proficiency at naming binary ionic compounds and writing their chemical formulas

Prepare for the Activity Work in groups of four. Play Salty Eights Card Game. Each player starts with eight cards. Players take turns putting down a compound When a player cannot put down a compound, the player draws cards until they can. The game ends when one player has no cards left. That player receives 20 bonus points. Points are counted based on how many cards used to make a compound. Points are deducted for compounds and noble gases left in each players hand.

Discussion Notes In general, atoms come together to form an ionic compound if the number of valence electrons totals 8 or a multiple of 8. Writing correct chemical formulas is a matter of keeping track of exactly how many atoms come together to make a compound. Creating correct chemical formulas is a matter of remembering some basic guidelines.

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) shell. • Noble gases already have eight valence electrons and don’t combine with other elements to make new compounds. They are already highly stable.

Check-in Which of these compounds are likely to form? A. Na 2 S B. K 2 Mg C. Al. Br 2 D. Na 3 N E. OCl F. Ca. O

Lesson 22: Isn’t it Ionic? Polyatomic Ions

Chem. Catalyst 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’ formula

Key Question What is a polyatomic ion?

You will be able to: • • Recognize and name polyatomic ions Write names and chemical formulas of compounds with polyatomic ions

Prepare for the Activity Work in groups of four. Play Ionic Grid Card Game. Four students share one deck of cards that are laid out faceup in a grid. Students take turns creating ionic compounds using the cards. Play three minute bonding game -- The whole class uses one deck of cards. Each student gets one card from the deck. The students have three minutes to mingle and form as many compounds as they can using their cards. When “Switch” is yelled – The student switches card with whoever is closest.

Discussion Notes Polyatomic ions contain more than one atom. Most polyatomic ions are anions with negative charges. Polyatomic ion - An ion composed of a group of atoms with an overall positive or negative charge. Most polyatomic ions are anions.

Discussion Notes (cont. ) The rule of zero charge can be used to predict the formulas of compounds that contain polyatomic ions. Compounds containing polyatomic ions have their own unique naming guidelines.

Wrap Up 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.

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?

Lesson 23: Alchemy of Paint Transition Metal Chemistry

Chem. Catalyst 1. What types of substances will you be creating in today’s lab? 2. What safety precautions are especially important for today’s lab? 3. Describe one of the procedures you will be completing in class today?

Key Question What types of compounds are made from transition metals?

You will be able to: • • Recognize transition metal compounds and their names Determine the charge on transition metal ions given their chemical formula

Prepare for the Lab Work in groups of four. • Wear goggles at all times. • Tie back loose hair, no dangling jewelry. • When heating a test tube, the open end of the test tube should never be pointed at anyone.

Discussion Notes Many of the paint pigments that artists historically used and continue to use are ionic metal-nonmetal compounds.

Wrap Up What types of compounds are made from transition metals? • Many of the colorful pigments used in painting are formed from metal-nonmetal compounds with transition metal cations. • Paint pigments in famous paintings can be as valuable as gold. A compound or element does not have to be gold to be valuable

Lesson 24: Shell Game Electron Configurations

Chem. Catalyst 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

Key Question What does the periodic table indicate about the arrangements of electrons?

You will be able to: • • • 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

Prepare for the Activity Work in groups of four. • Use the periodic table to determine the arrangements of electrons into subshells.

Discussion Notes The electron shells in the shell model of an atom (except for n=1) are divided into subshells. In an electron configuration, the number indicates the shell number, the letter indicates the subshell within the shell, and the superscript indicates the number of electrons in the subshell.

Discussion Notes (cont. ) 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. The number of electrons in each • The periodic table is organized in subshell blocks. • The order of filling of subshells does not always correspond to the numerical order of the subshells • The elements in the different subshell blocks have related properties.

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 s subshell can hold 2 electrons, the p subshell can hold 6 electrons, the d subshell can hold 10 electrons, and the f subshell can hold 14 electrons.

Wrap Up ( cont. ) What does the periodic table indicate about the arrangements 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.

Check-in Identify the element with this electron configuration 1 s 22 p 63 s 23 p 64 s 23 d 104 p 3