Ionic Compounds: Transfer of electrons Transfer of electrons are made up of positive and negative ions are made up of positive and negative ions –All of the positives and negatives organize nicely.  Negative-positive attract  Negative-negative and positive-positive repel –Ionic compounds form from the inside-out as solid crystals the inside-out as solid crystals Salt, NaCl 4.2 – Ionic and Covalent Compound Naming

Covalent Molecules: share electrons. share electrons. –These molecules clump together as solids, liquids or gases Covalent molecules are like a play-pit full of plastic balls  Each plastic ball = 1 covalent molecule of H 2 O  Pit full of balls = swimming pool full of water Water, H 2 O

Naming Ionic Compounds: Ionic compounds are composed of cations and anions. Ionic compounds are composed of cations and anions. –name of an ionic compound = cation anion-ide –Example: magnesium and oxygen  cation anion-ide  Magnesium ox + ide  magnesium oxide Magnesium oxide is used as a drying agent.

Example 2: what is the name of Ca 3 N 2 ?  Ca = calcium  N = nitrogen  Drop the end of the anion and add -ide  Calcium nitride Example 3: Example 3: What is the name of BaCl 2 ?  Barium chloride

Writing formulas for Ionic Compounds Remember: positive charges must = negative charges Example: what is the formula for magnesium phosphide?  Magnesium is Mg 2+ phosphorous is P 3–  Lowest common multiple of 2 and 3 is 6  3 Mg 2+ ions and 2 P 3– ions (6+ve charges and 6 –ve)  Mg 3 P 2

You try! What is the formula for calcium oxide?  calcium is Ca 2+ oxygen is O 2–  1 Ca 2+ ion and 1 O 2– ions  CaO

Drawing Formula Diagrams Examples on overhead: Examples on overhead: –Lithium nitride –Barium sulphide WS – 4.2 Writing Ionic Formulas WS – 4.2 Writing Ionic Formulas p. 187 Practice Problems (#1 odd letters) p. 187 Practice Problems (#1 odd letters) p. 188 Practice Problems (#2 even letters p. 188 Practice Problems (#2 even letters

Ionic Compound with a Multivalent Metal Some transitional metals are multivalent, meaning they have more than one possible charge). Some transitional metals are multivalent, meaning they have more than one possible charge). –On the periodic table, the most common form of the ion is listed on top –Roman numerals are used after the metal name to indicate which ion was used

Example: What is the formula manganese(III) sulphide? What is the formula manganese(III) sulphide?  This manganese is Mn 3+ sulphur is S 2–  Lowest common multiple of 3 and 2 is 6  2 Mn 3+ ions and 3 S 2– ions  Mn 2 S 3

You try! What is the name for TiF 4 ?  titanium can be Ti 4+ or Ti 3+ fluorine is F –  From the ratio in the formula you can find out it is Ti 4+ can find out it is Ti 4+  1 Ti 4+ ion and 4 F – ions  Titanium (IV) fluoride

Practice Problems p. 190 (#1 odd letters) p. 190 (#1 odd letters) p. 191 (#1 even letters) p. 191 (#1 even letters)

Polyatomic Ions Polyatomic ions, are made up of several atoms joined together (ironically, joined with covalent bonds) Polyatomic ions, are made up of several atoms joined together (ironically, joined with covalent bonds) –The whole group has a + or – charge, not individual atoms. What is the formula of sodium sulphate? What is the formula of sodium sulphate? Na + and SO 4 2– Na 2 SO 4

Example: What is the name of the compound KClO? K + = potassium ClO – = hypochlorite Potassium hypochlorite Example: What is the formula for Calcium nitrate? Ca 2+ and NO 3 - Ca(NO3)2 * Note the brackets around NO3 show there are two of the nitrate ions present

Practice Problems p. 193 (#1 and 2 odd letters) p. 193 (#1 and 2 odd letters) WS – 4.2 Ionic Naming WS – 4.2 Ionic Naming –May have all three Ionic compounds  Basic  Multivalent metals (need roman numerals)  Polyatomics

Naming Simple Covalent Compounds Prefixes are used before the atom name to indicate the number of atoms in the molecule.  Examples: CO = carbon monoxide, CO 2 = carbon dioxide Write the most metallic atom (furthest left) first, then add -ide to the end of the second atom’s name

Examples: W What is the name of the molecule Si3P6? –T–T–T–Trisilicon hexaphosphide What is the chemical formula for the molecule trinitrogen tetrachloride? –N–N–N–N3Cl4

Practice Problems p. 195 (#1 and 2 even letters) p. 195 (#1 and 2 even letters) WS – 4.2 Covalent Naming Assignment WS – 4.2 Covalent Naming Assignment

How do you know which type it is? To determine whether a compound is ionic or covalent: To determine whether a compound is ionic or covalent: - Examine the formula Ionic compounds start with a metal or the ammonium ion Ionic compounds start with a metal or the ammonium ion Covalent compounds start with a non-metal Covalent compounds start with a non-metal Take the Section 4.2 Quiz

Comparing Ionic - Covalent p. 197 (#1 and 2 all letters) p. 197 (#1 and 2 all letters) WS – 4.2 Mixed Chemical Naming WS – 4.2 Mixed Chemical Naming