AP Chem Ch3 Flashcards
What is a chemical formula?
A method for describing compositions of atoms (molecules, formula units, and/or compounds). There are various types such empirical formula (letters + ionic bonds), molecular “condensed” formula (letters + molecule), and molecular structural formula (2d bond structure + covalent bonds (molecule)).
Water of hydration
The water molecules that are found in crystalline structures (i.e., the hydrates).
Crystal
A periodic arrangement of atoms (or molecules).
Hydrates
Compounds with “trapped” water molecules.
How is a hydrate indicated in a formula?
A dot.
Prefix for ‘4’
Tetra
Prefix for ‘7’
hepta
Prefix for ‘9’
nona
Aqueous
Of water, typically referring to a solvent.
Why do equations need to be balanced?
Law of conservation of matter
Coefficients
A multiplier
Why can’t formulas be altered in an equation?
The equation is the given (by who?). Think of the pigments - you wanted a certain outcome.
Why can’t the subscripts be altered in an equation?
It would change the molecules involved.
Neutralization reaction
A specific type of double replacement reaction where the two reactants are pairs of acid + base. The products are salt and water.
What determines a substances pH?
How many free H+ atoms there are (these result from hydrogen bonds overpowering covalent bonds with H2O).
Formation reaction
Same as a synthesis reaction but the product must have a coefficient of one.
Addition reaction
Similar to a synthesis reaction except the molecules rather than elements are synthesized (this seems to be the case at least).
Net ionic reaction
An ionic reaction in aqueous solution. This typically results in one ionic substance from each group to react (with the other in the pair being a “spectator” ion).
Half-reaction
Half of the redox process (either oxidation or reduction).
Oxidation-reduction reactions (redox reaction)
A reaction where electron(s) are transferred.
Reduction
Gain of electrons (looses positive charge)
Oxidation
Loss of electrons.
Representative elements
Elements in the s & p blocks. They have regular properties and tend to follow uniform principles.
What elements tend to form cations?
Representative metals.
What elements tend to form anions?
Representative non-metals.
Typical electron configuration of transition metals and why it’s helpful.
Increasing by principle number. It helps to deduce the typical ions formed by the metal.
Polyatomic ion
Charged groups of atoms that are highly stable and tend to act as a unit in chemical reactions.
Pg 142, Table 3.3 of polyatomic ions
XX
Law of electroneutrality
Compounds must have neutral charge (note that polyatomic ions are technical compounds but are not considered here).
How to balance an ionic reaction
Bring the superscripts down as coefficients on the opposite reactant.
What types of elements are involved in ionic bonds?
Metal and non-metal
Naming with ions
- Cation before anion
- Cations name is used as is, with numerals to indicate charge if it can have different charges.
- Monatomic anions are prefixed with ‘-ide.’ Polyatomic are unique.
What happens to most ions in water?
They dissolve and separate into the cations and anions.
Solubility rules
- Compounds containing sodium or potassium cations or ammonium ions are soluble
- Compounds containing nitrate are soluble.
Driving forces that determine if a double-replacement will occur.
- Water is a strong driving force - if water is a product, it is very likely that a double-replacement is occurring.
- Formation of a precipitate (insoluble compound) is another indicator of a driving force.
- The formation of a covalent compound from an ionic reaction - many times in the form of organic acids or gases).
Net Ionic Equations
An equation that cancels out the “spectator” ions. See the link for how - http://www.occc.edu/kmbailey/Chem1115Tutorials/Net_Ionic_Eqns.htm
Spectator ions
Ions that are a reactant and product of a reaction but don’t undergo any change. For instance, they start in an aqueous solution as single ions and end as single ions.
What is a single replacement reaction between?
An element and an ionic compound which then forms a new element and ionic compound.
Two types of single replacement reactions
- Metal element reactant becomes a cation product
2. Nonmetal element reactant becomes an anion product.
