Chpt. 8, Ionic Compounds and Metals Flashcards
ionic bonds
There is no such thing! Ions (ionic compounds) are held together by electrostatic forces, not by bonds. Many people refer to it as ionic bonds anyways, they just don’t sound educated.
ionic compound
a bond in which positively charged cations are attracted to negatively charged anions due to their opposing charges
ionic crystals
more than two atoms typically combine with each other to form larger ionic crystals; the pattern in which the ions arrange themselves is called a crystal lattice
unit cell (of a compound)
the smallest repeating unit that makes up a crystal lattice
crystal lattice
the pattern in which the ions arrange themselves
properties of ionic compounds
hard, brittle, high melting and boiling points, conduct electricity when melted or dissolved
Why are ionic compounds hard?
The great resistance to movement that comes are a result of the attraction between their positive and negative charges makes them hard.
Why are ionic compounds brittle?
The ions in a crystal lattice are lined up precisely, and unless they remain in exactly that configuration, they become very unstable and will shatter. When subjected to force, the ions will often move relative to one other, and will no longer be in the necessary, precise position.
Why do ionic compounds have high melting and boiling points?
The strong electrostatic forces that occur as a result of the attraction between cations and anions is such that they must be subjected to a relatively large amount of energy to break them apart.
Why do ionic compounds conduct electricity when melted or dissolved?
Moving ions are one way in which electricity can be conducted, and when ionic compounds are either melted or dissolved, they are free to move around.
components of the name of an ionic compound
the first name of the compound names the cation, or positively charged ion (t looks like a plus sign, for positive)
2nd comes the anion, or negatively charged ion in the molecule
for any given compound, the charges on the anion and cation must balance out; some elements have multiple types of cations or anion, and these must be memorized
Roman numerals
Roman numerals can be used to indicate the specific positive charge on the cation in cases where the cation may have multiple possible positive charges; the value of the numeral corresponds to the actual charge in the given instance
Roman numerals = (anion charge)(#of anions) / (# of cations)
common polyatomic ions, 1-4, (#) = superscript
NH4(+1) = ammonium NO2(-1) = nitrite NO3(-1) = nitrate OH(-1) = hydroxide
common polyatomic ions, 4-8, (#) = superscript
CN(-1) = cyanide MnO4(-1) = permanganate HCO3(-1) = bicarbonate C2H3O2(-1) = acetate
common polyatomic ions, 9-13, (#) = superscript
CH3COO(-1) = acetate CO3(-2) = carbonate SO3(-2) = sulfite SO4(-2) = sulfate PO4(-3) = phosphate
