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“Do Now” for 2/8/10

“Do Now” for 2/8/10. Put your homework out on your desk to get stamped for completion. If you don’t have it with you NOW it is late. ( No you can’t go get it so don’t ask.) Respond to the following in complete sentences:

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“Do Now” for 2/8/10

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  1. “Do Now” for 2/8/10 • Put your homework out on your desk to get stamped for completion. If you don’t have it with you NOW it is late. (No you can’t go get it so don’t ask.) • Respond to the following in complete sentences: • What is the difference between the # of e- that an element has versus the # of valence e- that an element has? • How is the number of valence e- related to the charge that an ion of a particular element will have?

  2. For #1: total # of e- vs. # of valence e- • In a neutral atom, the # of e- is equal to the # of protons (which is = to the atomic #!) • The # of valence e- is specifically referring to the # of e- in the outer shell, or highest energy level. • An element will never have more than 8 valence e- This is a Carbon atom. # of protons = 6 # of neutrons = 6 # of e- = 6 1s22s22p2 2 is the highest energy level, so you would add up the e- found in that level and this would = the # of valence e-

  3. For #2: Relating # of valence e- to charge of the ion • Remember the octet rule: All atoms want to be happy with 8 e- in their outermost shell. • They will either gain or lose e- to do this. • If an element LOSES e-, it will have a POSITIVE charge of however many e- it lost • Groups 1, 2, and 13 will lose e- • If an element GAINS e-, it will have a NEGATIVE charge of however many e- it gained • Groups 15, 16, and 17 will gain e-

  4. Determining Charges and Writing Ions Is the element a transition metal? Yes. Look at your cheat sheet to see if it can have multiple charges No. Figure out how many valence electrons it has by using your Periodic Table. Example: Has more than 4 val. e- : It will gain e- until it reaches noble gas configuration Has less than 4 val. e- : It will lose valence e- until it reaches noble gas configuration • Cl has 7 val. e- • Cl will gain 1 e- to reach noble gas notation • So you write the ion as: Cl1- • Write the symbol for the element. • The charge will be negative by how many e- it gained. • Write the symbol for the element. • The charge will be positive by how many e- it lost.

  5. Ionic Names to Formulas Part I. Look at the Cation. Is it ammonium? Cation Yes. Write NH4+ No. Is it a transitional metal? Yes. Does it have a Roman Numeral after it? No. Write the symbol of the element and determine the charge of the ion from the periodic table. Yes. This gives you the + charge. Write it after the element’s symbol. No. Write the symbol for the element and check your cheat sheet for the charge. If none is listed, write 2+ Part II. Look at the Anion. Does it end in “ide” and is NOT cyanide, amide, hydroxide, peroxide or azide? Anion Yes. It is monatomic . Write the name of the element that corresponds to the root word before “ide” No. It is polyatomic (ends in “ate” or “ite” or is cyanide, amide, hydroxide, peroxide, or azide). Look up on your Polyatomic ion sheet for the formula and charge. Write the symbol of the element and determine the charge of the ion from the periodic table. Criss-cross the charges of the cation (Part I) and anion (Part II.) Reduce if needed. Remember, the net charge on the compound should be neutral!! Balance

  6. Focus on the cation. Is it NH4+? Ionic Formulas to Names No. Is it a transition metal? Yes. Write Ammonium. Yes. Does this transition metal have various oxidation numbers? (check your cheat sheet or p. 219 in your text) No. Write the name of the element. Focus on the anion. Is it monatomic (1 capital letter)or polyatomic (more than 1 capital letters)? • Yes. • Reverse criss-cross. The subscripts should become the charges (superscripts) • Write the name of the element and the oxidation # in Roman Numerals in () after the name. Monatomic. Write the root of the element’s name and add “ide” to the end. Polyatomic. Look up the name for the polyatomic compound on your sheet. Be careful that you are writing the correct one! Cations Anions

  7. For these slides and additional info: • Go to the Schurz website  Academics  Classes/Homework • Select “Science” • Select “Karen M. Perry” (NOT “Chemistry” or the number of HW assignments) • To the right, you’ll see a box with hyperlinks to “Links” and “PowerPoint Slides from Lecture” • These are under the PowerPoint slides. • There are helpful tutorials and games under the links section that are worth checking out as well!

  8. Chemistry: Ions in Chemical CompoundsSelected problems from your homework.

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