a. protons b. neutrons c. electrons d. morons

a. protons b. neutrons c. electrons d. morons

a. electrons near the nucleus of the atom b. middle energy level(s) c. valence electrons

a. electrons near the nucleus of the atom b. middle energy level(s) c. valence electrons

a. 1 b. 4 c. 8 d. 10

a. 1 b. 4 c. 8 d. 10

 Atoms are chemically stable (or resistant to change) when their valence shells are completely filled with electrons.  For most atoms, 8 electrons are needed to be chemically stable.

 The valence shells of the Noble gases are already completely filled with electrons.  All of the Noble Gases, with the exception of helium, have 8 valence electrons.  Helium has only two electrons.  Therefore, the first energy level is full, making it stable with its two valence electrons.

a. Bohr Models b. Lewis Dot Diagrams c. electron configuration d. all of these

a. Bohr Models b. Lewis Dot Diagrams c. electron configuration d. all of these

Sodium atom Chlorine atom

a. Bohr Models b. Lewis Dot Diagrams c. both of these

a. Bohr Models b. Lewis Dot Diagrams c. both of these

 have achieved a Noble Gas configuration (which have a complete set of valence electrons) (In other words, atoms are stable when they have bonded with other atoms to completely fill their outer-level electron shells).

1. Ionic Bonds = usually metal + nonmetal 2. Covalent Bonds = nonmetal + nonmetal

an atom that has gained or lost one or more electrons, therefore it has a positive or negative charge

 Usually forms between a metal and a nonmetal  Is the force of electrostatic attraction between positively and negatively charged ions

Na = sodium Cl = chlorine

 If an atom loses electrons it becomes ____ charged.  If an atom gains electrons, it becomes ____ charged.

 If an atom loses electrons it becomes _positively_ charged.  If an atom gains electrons, it becomes _negatively_ charged.

 Metals tend to lose electrons, becoming a positive ion (cation).  Nonmetals tend to gain electrons & become negative ions (anion).

1. NaCl 2. CO 2 3. H 2 O 4. MgCl 2 5. C 4 H 10

1. NaCl (ionic) 2. CO 2 (covalent) 3. H 2 O (covalent) 4. MgCl 2 (ionic) 5. C 4 H 10 (covalent)

 Superscript - “written above”  Examples: Na +, Mg 2+, Cl -, O 2-

Indicates the elements in a compound and the ratio of the atoms of those elements in one unit of the compound.

Examples: NaCl; H 2 O The “2” in H 2 O is a subscript. Subscript (“written below”)indicates the number of atoms of an element in a unit of that compound.

What is the ratio of sodium to chlorine in NaCl? What is the ratio of hydrogen to oxygen in H 2 O?

What is the ratio of sodium to chlorine in NaCl? 1:1 What is the ratio of hydrogen to oxygen in H 2 O? 2:1

1. Determine the oxidation number of each ion (the number of electrons an atom gains or loses) The oxidation number for the representative elements can be determined from its position on the periodic table. Oxidation Numbers for transition elements are determined from their negative ions.

1. Write the symbol of the positive ion first. 2. Write the symbol of the negative ion. 3. Add the superscripts. Is the sum zero? 4. If the sum does NOT equal zero, criss-cross the ionic charges. Check it: 2(+3) = +6 3(-2) = = 0 MUST BE IN THE LOWEST WHOLE-NUMBER RATIO

1. Write the name of the positive ion first. 2. If the positive ion has more than one common charge (i.e., transition metals), write the charge as a Roman Numeral. (All transition metals except Ag 1+, Zn 2+ and Cd 2+ have more than one common ionic charge & must include Roman Numerals to represent the charge of the ion). 3. Write the root of the negative ion’s name. 4. The ending is changed to -ide.

1. sodium and chlorine 2. calcium and chlorine 3. aluminum and chlorine

Na 1+ Cl 1- Formula: NaCl Name of compound: sodium chloride sodium ion chloride ion

Ca 2+ Cl 1- Formula: CaCl 2 Name: Calcium Chloride

Al 3+ Cl 1- Formula: AlCl 3 Name: Aluminum Chloride Cl 1-

 A group of atoms that shares a common ionic charge.  Polyatomic ions must be memorized --- there’s no way around it!  See the chart of common ions.

 Ammonium ion: NH 4 1+  Nitrate ion: NO 3 1-  Nitrite ion: NO 2 1-  Hydroxide ion: OH 1-  Sulfate ion: SO 4 2-  Carbonate ion: CO 3 2-  Phosphate ion: PO 4 3-

Na 1+ NO 3 1- Sodium ion Nitrate ion Chemical Name: sodium nitrate Chemical Formula: NaNO 3

NH 4 1+ Ammonium ion NH 4 1+ Ammonium ion SO 4 2- Sulfate ion Chemical Name: ammonium sulfate Chemical Formula: (NH 4 ) 2 SO 4

NH 4 1+ Ammonium ion NH 4 1+ Ammonium ion PO 4 3- Phosphate ion Chemical Name: ammonium phosphate Chemical Formula: (NH 4 ) 3 PO 4 NH 4 1+ Ammonium ion

Ca 2+ calcium ion NO 3 1- Nitrate ion NO 3 1- Nitrate ion Chemical Name: calcium nitrate Chemical Formula: Ca(NO 3 ) 2

 CuBr 2 is named Copper (II) bromide Cu 2+ Br 1-  FeCl 3 is named iron (III) chloride Fe 3+ Cl 1-

Writing Ionic Formulas Using the Criss-Cross Method Chemical Name: iron (III) sulfide The Roman Numeral III, represents the +3 charge iron has in this compound.

 These transition elements ALWAYS have the following oxidation numbers: Ag + Cd 2+, Zn 2+

 AgBr is named silver bromide, and NOT silver (I) bromide, because silver always has a 1+ oxidation number.  The same is true for compounds containing Cadmium or Zinc. (Cd and Zn are always 2+)

Copper (I) and (II) = Cu + and Cu 2+ Iron (II) and (III) = Fe 2+ and Fe 3+ Chromium (II) and (III) = Cr 2+ and Cr 3+ Lead (II) and (IV) = Pb 2+ and Pb 4+

1. FeS 2. CuCl 3. PbBr 4

1. Iron (II) sulfide 2. Copper (I) chloride 3. Lead (IV) bromide

1. lead (II) bromide 2. chromium (II) sulfide 3. copper (II) iodide

1. PbBr 2 2. CrS 3. CuI 2

 Result from the formation of ionic bonds.  Exist usually between a metal and a nonmetal  Are fun to name and write formulas for once you know the rules!