Names and Formulas for Ionic Compounds Types of

Names and Formulas for Ionic Compounds

Types of ions • Monatomic ion – ion with one atom • Mg 2+ magnesium ion • Cl- chloride ion • Polyatomic ion – ion with more than one atom • NH 4+ • NO 3 - ammonium nitrate

Ionic Compound Marriage Metals are like men Nonmetals are like woman Typically who changes their last name?

Naming Ca”t”ions • Monatomic cation name stays the same – Sodium, Na goes to sodium ion, Na+ – Calcium, Ca goes to calcium ion, Ca 2+ • Polyatomic cation - look up in chart – NH 4+ ammonium

Naming Anions • The name changes in a monatomic anion • The ending for a monatomic anion is ______ide (like a bride changes her last name) – chlorine, Cl goes to chloride ion, Cl– Fluorine, F goes to fluoride ion, F • Polyatomic anion look up in chart – OH- hydroxide – SO 42 - sulfate

Question Time Given the neutral atom, give the charge and name of the monatomic ion that will form. (Look at periodic table group numbers for help. ) 1. 2. 3. 4. 5. Na Cl Mg S P Na+ Cl. Mg 2+ S 2 P 3 - sodium cation chloride anion magnesium cation sulfide anion phosphide anion

Name the following polyatomic ions. (use your chart!) 6. NH 4+ ammonium cation hydroxide anion 7. OH− 8. SO 32− sulfite anion 9. SO 42− sulfate anion cyanide anion 10. CN−

Naming ionic compounds • Name the cation first and then the anion second (+ then -) • Example: Cs. F – Monatomic cations use the element name • Cs+ = cesium – Monatomic anions – change the ending to ide • F - = fluoride cesium fluoride

Will these form an Ionic Compound? If so what will the compound name be? 1. 2. 3. 4. 5. Mg Al Mg Na C Al S O N S No Yes two metals aluminum sulfide Yes magnesium oxide Yes sodium nitride No two non-metals

Formula Unit • Formula Unit—the smallest whole number ratio of ions in a compound • Na. Cl versus Na 2 Cl 2 • Correct: Sodium Chloride Na. Cl

What will the formula be? Ø In ionic compounds, we must balance charges to form a neutral compound Ø To do that, we “crisscross the charges” Ø Always reduce to get the formula unit Ca + N Ca 2+ + N 3 Ca 3 N 2 Both have a total charge of 6 (3 Ca 2+ = +6; 2 N 3 - = -6)

Practice 1. 2. 3. 4. 5. Given the following elements, predict the formula. (hint first identify the ion charge) K, Br Ca, Cl Li, S Mg, N Ba, P

Formula Unit with Polyatomic ions • Sometimes you will need to use more than one polyatomic ion to balance a charge. • If so, you need to put it in parenthesis (like a package) and use a subscript for the multiple number Ex: Mg 2+ and NO 3 These charges do not balance so we must crisscross them Mg 1(NO 3)2 (we don’t need the 1) Mg (NO 3)2

Transition Metal Ions • Metals form cations • Some transition metals only have one ionic charge – Silver (Ag+), Cadmium (Cd 2+), Zinc (Zn 2+) • Some transition metals can take on more than one charge. – Copper (Cu+, Cu 2+) • Charge is determined from the number of electrons lost

Naming Transition Metal Ions • If a transition metal has more than one charge, the charge is written as a Roman numeral in parenthesis • Some metals need a middle name • Fe (iron) has more than one charge: 2+ and 3+ – Fe 2+ – Fe 3+ iron(II) iron(III) • If the transition metal only has one charge, no Roman numeral is needed

Naming Ionic Compounds with Transition Metals Given: Fe 2 O 3 • First find the charges of the ions • Then name the cation followed by the anion – Iron(III) oxide • Try this one: Fe 3 P 2 • the charge on iron is a 2+ • iron(II) phosphide

Question Time Identify the charge on the transition metal: 1. copper (II) nitrate 2. gold (I) chromate 2+ 1+ Name the compound: 1. Fe. O 2. Zn(OH)2 3. Co. PO 4 iron (II) oxide zinc hydroxide cobalt (III) phosphate