Vocabulary n Chemical Bond attractive force between atoms

Vocabulary n Chemical Bond – attractive force between atoms or ions that binds them together as a unit – bonds form in order to… § increase stability Courtesy Christy Johannesson www. nisd. net/communicationsarts/pages/chem

Chemical Bonding atoms give up or gain electrons and are attracted Na loses an e– Na 1+ + e– (Metal) ionic compounds = salts Cl gains an e– Cl + e– Cl 1– (Non-Metal) Na 1+ + Cl 1– Na. Cl K 1+ + NO 31– KNO 3 where NO 31– is a polyatomic ion: a charged group of atoms that stay together

Ionic Bonding Na. Cl n=3 - n=2 - - - - Na [Ne]3 s 1 - - - + - - - - - Cl [Ne]3 s 23 p 5 - - - Na+ [Ne] - - - Cl[Ne]3 s 23 p 6 Transfer of electrons to achieve a stable octet (8 electrons in valence shell).

Properties of Ionic Compounds VERY HARD each ion is bonded to several oppositelycharged ions HIGH MELTING POINTS many bonds must be broken BRITTLE with sufficient force, like atoms are brought next to each other and repel

Writing Chemical Formulas

The Swap n Drop Method The Swap n Drop method is an easy way to determine the formula of any ionic compound. n The ionic compound can be the simple (binary) ionic compound with just two elements, or one that has a polyatomic ion as part of it. n You can get the oxidation values directly off of the periodic table for most elements or they are part of the “Polyatomic Cheat Sheet”. n

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Calcium and Nitrogen 1. Ca N 2. 3. Ca 2+ Ca 3 N 2 N 3 -

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Be Br Br 1. Be 2+ 3. Be. Br 2 Br 1 -

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Lithium Oxide: 1. Li O 2. 3. Li 1+ Li 2 O O 2 -

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Magnesium Nitride: 1. Mg N 2. 3. Mg 2+ Mg 3 N 2 N 3 -

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Lithium Chloride: 1. Li Cl 2. 3. Li 1+ Li. Cl Cl 1 -

Formulas With Transition Metals The Swap n Drop method is also used when dealing with metals that have more than one oxidation number. (Copper, Iron, Lead, or Tin) n The oxidation number for these metals can be found in the name of the compound that contains them. n Examples: n – Iron (II) oxide – the Iron (Fe) used here has an oxidation number of 2 – Lead (IV) sulfide – the Lead (Pb) used here has a oxidation number of 4.

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Iron (III) Oxide: 1. Fe O 2. 3. Fe 3+ Fe 2 O 3 O 2 -

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Lead (II) Chloride: 1. Pb Cl 2. 3. Pb 2+ Pb. Cl 2 Cl 1 -

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Copper (I) Phosphide: 1. Cu P 2. 3. Cu 1+ Cu 3 P P 3 -

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Tin (II) Sulfide: 1. Sn S 2. Sn 2+ 3. Sn 2 S 2 4. Sn. S S 2 -

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Lead(IV) Oxide: 1. Pb O 2. Pb 4+ 3. Pb 2 O 4 4. Pb. O 2 -

Polyatomic Ions n Polyatomic ions are clusters of atoms that stay together as one unit and carry an overall charge. Most polyatomic ions are negatively charged. .

Polyatomic Ionic Compounds Parenthesis n You need more than one polyatomic ion in your formula…This means that you will have to use brackets. Use parenthesis whenever you need more than one polyatomic ion in the formula. n Example: Iron (III) nitrate… – Start with symbols and combining capacities… Fe 3 NO 31 – After the Swap n Drop, you may get one of two possibilities… § Fe. NO 33 OR Fe (NO 3)3 The second option is right because it says you need two nitrate clusters to go with every iron atom. The first option, which did not use reads as one iron atom and thirty-three oxygen atoms. n Fe(NO 3)3 is the correct formula! Use the parenthesis! n

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Sodium Nitrate: 1. Na NO 3 2. 3. Na 1+ (NO 3)1 - Na(NO 3)

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Calcium Chlorate 1. Ca Cl. O 3 2. 3. Ca 2+ (Cl. O 3)1 - Ca(Cl. O 3)2

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Lithium Phosphate: 1. Li PO 4 2. 3. Li 1+ (PO 4)3 - Li 3(PO 4)

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Aluminum Sulfate: 1. Al SO 4 2. 3. Al 3+ (SO 4)2 - Al 2(SO 4)3

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Tin (IV) Carbonate: 1. Sn CO 3 2. 3. 4. Sn 4+ (CO 3)2 - Sn 2(CO 3)4 Sn(CO 3)2 Reduce!

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Ammonium Phosphate: 1. NH 4 PO 4 2. 3. ( NH 4)1+ ( PO 4)3(NH 4)3 ( PO 4)

Swap it and Drop it Steps (in order) 1. Write the chemical symbols. 2. Write the oxidation number over the symbols. 3. Swap it and Drop it. 4. Reduce – if necessarythe same numbers or a 2 & 4 together. Magnesium Carbonate: 1. Mg CO 3 2. 3. 4. Mg 2+ (CO 3)2 - Mg 2(CO 3)2 Mg(CO 3) Reduce!