Ionic Compounds

Learning Goals Describe the relationship between chemical formulae, composition, and names of ionic compounds Describe the properties of ionic compounds

Warm-Up 1.Why do we name objects, people, pets, elements, etc.? 2.Do all names stay the same? Do your names always stay the same?

Ionic Bonding Metals – Electron donors – Donate their valence electrons to become a positive ion (cation) Nonmetals – Electron acceptors – Accept valence electrons to become a negative ion (anion)

Ionic Bonding

The oppositely charged ions are attracted to each other by a force called an ionic bond

Most ionic compounds: Have high melting points Are hard and brittle Are soluble in water Form electrolytes (conduct electricity) when dissolved in water Properties of Ionic Compound

Crystal Lattice Structure Ionic compounds form crystal lattices This explains why they have high melting points and are hard but brittle Na + Cl -

Ionic Compounds in Water When ionic compounds dissolve, they separate into their ions The free ions can now move and conduct electricity

Naming Ionic Compounds Many ionic compounds are made up of a metal and a nonmetal The metal is named first, followed by the nonmetal Change the nonmetal ending to “ide” E.g. aluminum and oxygen = aluminum oxide magnesium and chlorine = magnesium chloride Do NOT capitalize

Common AnionsName H-H- hydride F-F- fluoride Cl - chloride Br - bromide I-I- iodide O 2- oxide S 2- sulfide N 3- nitride P 3- phosphide

Writing the Chemical Formula Step 1: Write the symbols of the elements, with the metal on the left-hand side and the non-metal on the right-hand side. MgCl Step 2: Add the ionic charge of each ion above the symbol +2-1 MgCl

Step 3: Determine the number of ions required to bring the charge to zero. 1(+2) +2(-1) = 0 Mg Cl Step 4: Write the chemical formula using the (red) coefficients in front of each bracket as subscripts Mg 1 Cl 2 Note: Do not write the subscript “1” The chemical formula for magnesium chloride is MgCl 2

Crisscross Method Step 1: Write the symbols of the elements and their ionic charges Mg 2+ Cl - Step 2: Crisscross the numbers of the ionic charges so that they now become subscripts Mg 2+ Cl - MgCl 2

Multivalent Metals Some metals have multiple ionic charges. E.g. Write the chemical name of CuBr 2. Copper could have either +1 or +2 Each bromide ion has a charge of -1, so the total charge of bromide ions is 2(-1). The ionic charge of copper in this compound is +2 Roman numerals are included ONLY if the metal has more than one ionic charge. The name of CuBr 2 is copper (II) bromide

Practice!