Monday, January 24, 2011 Do Now: Ionic bonds require gained or lost (exchanged) electrons. Covalent bonds involve shared electrons. Homework: Due tomorrow:

Monday, January 24, 2011Do Now: Ionic bonds require gained or lost

(exchanged) electrons. Covalent bonds involve shared electrons.

Homework: Due tomorrow: pg. 207 #30-41 (chapter 7)

Things to do: Review lesson stepsDiscuss homework that is due (Goldilocks

Planet)Discuss Do NowBegin HW

Ionic and Covalent BondingIonic bonds require gained or lost

(exchanged) electrons. Covalent bonds involve shared electrons.

Review: electron dot structures

Homework pg. 207 #30-41Due on Tues. Jan 25Do you have a book?If not, you should copy the questions from

this display (abbreviate to go faster)We’ll discuss answers briefly, and spend

more time after writing the questions.PLEASE GIVE NAME, DATE, HOUR AND

PAGE/ PROBLEM NUMBERS ON A PIECE OF NOTEBOOK PAPER… RIGHT NOW.

PG. 207 #30DESCRIBE TWO WAYS THAT AN ION FORMS

FROM AN ATOM.

An ion forms when an atom gains or loses an electron.

Pg. 207 #31State the number of electrons either lost or gained

in forming each ion.A. Br- one electron is gainedB. Na+ one electron is lostC. As 3- three electrons are gainedD. Ca 2+ two electrons are lostE. Cu+ one electron is lostF. H- one electron is gained

Ms. Gall’s summary: Each electron has ONE NEGATIVE CHARGE. A neutral atom has equal numbers of protons and electrons. When an electron is lost, the atom is left with more positive charges. When an electron is gained, the atom has extra negative charges.

Pg. 207 #32Name each ion. Is it a cation or anion?

A. Br- one electron is gained Bromine -, anion

B. Na+ one electron is lost Sodium +, cation

C. As 3- three electrons are gained Astatine 3-, anion

D. Ca 2+ two electrons are lost Calcium 2+, cation

E. Cu+ one electron is lost Copper +, cation

F. H- one electron is gained Hydrogen -, anion

Pg. 207 #33Define valence electron.

Pg. 207 #34How many electrons does each atom have?

What group is each in?A. nitrogen 7 electrons, group 15B. Lithium 3 electrons, group 1C. phosphorusD. BariumE. Bromine 35 electrons, group 17F. Carbon

Pg. 207 #35Write electron dot structures for each:A. ClB. SC. AlD. Li

Pg. 207 #36How many electrons must each atom lose to

attain a noble- gas electron configuration?

(Ms. Gall says… some “prefer” to GAIN electrons to make a stable valence shell octet. Since the question says – how many must it LOSE- I can simply give its number of electron dots.)

A. CaB. AlC. LiD. Ba Barium will LOSE 2

electrons; it’s found in column 2.

Pg. 207 #37Write the formula for each ion formed when

the element LOSES ITS VALENCE ELECTRONS>

(Ms. Gall says- all the answers LOSE electrons; all will be positively charged.)

A. aluminum, Al 3+B. lithiumC. bariumD. potassium, K+E. calciumF. Strontium, Sr 2+

Pg. 207 #38. DEEP THOUGHT ALERT!Why do nonmetals tend to form anions

when they react to form compounds?

Nonmetals are on the right side of the periodic table; they have a nearly full valence shell. It’s “easier” for them to gain a couple of electrons (become anions) than it is to LOSE that many electrons to empty out the valence shell.

Pg. 207 #39What is the formula of the ion formed when

the following elements gain or lose electrons and attain noble- gas configurations?A. sulfur S 2-

B. sodium Na +

C. fluorine F-

D. phosphorus P3-

Pg. 207 #40How many electrons must be GAINED by

each of the following atoms to achieve a stable electron configuration?A. N will GAIN 3 ELECTRONSB. SC. ClD. P

Ms. Gall says: subtract the number of electron dots from eight to get the answer. For example, N has 5 electron dots; 8-5 = 3. N will GAIN 3 electrons.

Pg. 207 #41Which of the following pairs of atoms would you

expect to combine chemically to form an ionic bond?

(Ms. Gall says: if the atoms BOTH have 1,2, 6, or 7 valence- shell electrons (dots), then you can expect an ionic bond. If either has 3,4, or 5 valence electrons, it is likely to be a covalent bond. )

A. Li and S………… IONICB. O and S……………. NOT IONICC. Al and O………….NOT IONIC

Pg. 207 #41Which of the following pairs of atoms would you

expect to combine chemically to form an ionic bond?

(Ms. Gall says: if the atoms BOTH have 1,2, 6, or 7 valence- shell electrons (dots), then you can expect an ionic bond. If either has 3,4, or 5 valence electrons, it is likely to be a covalent bond. )

D. F and Cl……….NON-BONDING (BOTH HAVE 7)E. I and K………..IONICF. H and N……………NON-IONIC