# Do Now Label the following as element or compound:  Mg  O 2  H 2 SO 4  FI Find the number of atoms in the following elements/compounds:  Mg  O 2.

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Do Now Label the following as element or compound:  Mg  O 2  H 2 SO 4  FI Find the number of atoms in the following elements/compounds:  Mg  O 2  H 2 SO 4  FI

The Octet Rule Key Point #1: The octet rule says that atoms are most stable (happy) when they have 8 valence electrons

The Octet Rule - Review We’ve talked about ions before – how atoms will gain or lose electrons in order to get eight valence electrons An atom that has gained an electron has a negative charge An atom that has lost an electron has a positive charge

Key Point #2: Copy the chart on the board This chart is an easy reference to see what type of ion an element will form

But why? Key Point #3: For atoms in groups 1, 2 and 13, it is easier to lose electrons. For atoms in groups 14, 15, 16, and 17, it is easier to gain electrons.

Why do I need to review this information on ions? So we can predict how atoms will bond together. Watch this…

Just in time for Halloween! There is a TRICK to figure out what the ionic compound between a metal and a nonmetal will be.

Kris Kross Method! Ca 3 As 2 Ca 2+ As 3-

Key Point #4: Kriss Kross Method: Write down the stable ions and cross the charges to make them subscripts Na 1+ Cl 1- NaCl Li 1+ O 2- Li 2 O

Use the charges: Group 12131415161718 Charge 1+2+3+4-3-2-1-0

Which charge ALWAYS comes first? POSITIVE!!

Guided Practice WHITEBOARDS! I will put a problem on the board. On your whiteboard, use the KRISS KROSS method to determine the compound

K F Ba N Ga O Ca Cl K Si Co I

K 1+ F 1- Ba N Ga O Ca Cl K SiCo I

KF Ba N Ga O Ca Cl K SiCo I

KF Ba 2+ N 3- Ga O Ca Cl K SiCo I

KF Ba 3 N 2 Ga O Ca Cl K SiCo I

KF Ba 3 N 2 Ga 3+ O 2- Ca Cl K SiCo I

KF Ba 3 N 2 Ga 2 O 3 Ca Cl K SiCo I

KF Ba 3 N 2 Ga 2 O 3 Ca 2+ Cl 1- K SiCo I

KF Ba 3 N 2 Ga 2 O 3 CaCl 2 K SiCo I

KF Ba 3 N 2 Ga 2 O 3 CaCl 2 K 1+ Si 4- Co I

KF Ba 3 N 2 Ga 2 O 3 CaCl 2 K 4 SiCo I

K F Ba N Ga O Ca Cl K Si Co I You don’t know about transition metals! So.. the problem must tell you the number of electrons. Cobalt (II) means that Cobalt gives up 2 electrons

K F Ba N Ga O Ca Cl K Si Co 2+ I 1-

K F Ba N Ga O Ca Cl K Si CoI 2

Independent Practice Room should be silent during independent practice 1. For each pair find the STABLE ION 2. Kris Kross! A. Mg O B. Na Br C. Rb P D. Be F E. Ca S

Exit Slip 1. For each pair find the STABLE ION 2. Kris Kross! A. K Cl B. Li N C. Ca O Homework! Writing formulas worksheet. Use the KRISS KROSS method to complete Due tomorrow

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