Chapter 3 Flashcards
compound
when two or more elements combine to form a compound, an entirely new substance results
chemical bonds
hold together compounds composed of atoms, and result from the attractoins between the charged particles.
Ionic bonds
occur between metals and nonmetals, and involve the transfer of electrons from one atom to another.
covalent bonds
occur between two or more nonmetals, involve sharing of electrons. electrons that are shared have a lower potential energy then they would on an isolated atom because they interact with the nucleus of both atoms.
Ionic bonds occur because
oppositely charged ions attract one another by electrostatic forces, which results in an ionic compound
Ionic compound
in the solid phase is composed of a lattice or three dimensional array of alternating cations and anions
Covalently bond atoms compose a
molecule
Molecules are..
independent of the other molecules, and are not covalently bound to eachother. therefore covalently bonded compounds are called molecular compounds
chemical formula
quickest and easiest way to represent a compound. indicates the elements present in the compound and the relative number of atoms or ions of each
chemical formula categorizations
empirical, molecular, structural
empirical formula
gives the relative number of atoms of each element in a compound. ex HO for hydrogen perioxide (Hsub2Osub2).
molecular formula
gives the actual number of atoms of each element in a molecule of a compound. ex Hsub2Osub2 for hydrogen peroxide
structural formula
uses lines to represent covalent bonds, and shows how atoms in a molecule are connected or bonded to eachother. (more visual)
ball and stick molecular model
represents atoms as balls and chemical bonds as sticks
space filling molecular model
atoms fill the space between eachother to more closely represent our best esimates for how a molecule might appear if scaled to visible size.
atomic elements
exist in nature with single atoms as their basic units. includes most elements
molecular elements
do not normally exist in nature with single atoms as their basic units. instead they exist as molecules of two or more atoms
molecular compounds
are usually composed of two or more covalently bonded nonmetals
ionic compounds
are compose of cations(usually metal) and anions(usually one or more nonmetals) bound together by ionic bonds
formula unit
the basic unit of an ionic compound, it is the smallest electrically neutral collection of ions in an ionic compound
polyatomic ion
an ion composed of two or more atoms
Naming Ionic compounds by..
common names and systematic names
common names
nicknames of sorts learned by familiarity
systematic names
chemist developed names for different types of compounds including ionic ones.
Steps in naming an ionic compound
- Identify it as one, usually composed of metals and nonmetals
- Determine which type depending on the metal in the compound,
a) metal whose charge is invariant from one compound to the next, no special notation needed
b) metal with a charge that differs in different compounds(often transition metals, but not always). the cation must be identified (+2,+3…)
binary compounds
contain only two different elements
naming binary ionic compounds(one type of cation)
name of cation(metal),Base name of anion(nonmetal)+ -ide
naming binary ionic compounds(more than one kind of cation)
name of cation(metal), charge of cation(metal) in roman numerals in parentheses, base name of the anion(nonmetal) + -ide
Naming ionic compounds containing polyatomic ions
name polyatomic ions the same way as other ionic compunds, except that use the name of the poly atomic ion whenever it occurs. ex. NaNOsub2, is named according to its cation Na+(sodium), and its polyatomic anion, NOsub2- (nitrate) ex FeSOsub4 = iron(II) sulfate
Oxyanions
most polyatomic ions, contain oxygen and another element.
Naming Oxyanions
when a series of oxyanions contain different numbers of oxygen atoms they are named systematically according to the number of oxygen atoms in the ion.
Oxyagnions prefixes and suffixes
if only two in a series then the one with more has the ending -ate, and the one with fewer -ite.
if there are more than two ions in a series the prefixes hypo- (meaning less than) and per-(meaning more than) are used.
Hydrates
ionic compounds that contain a specific number of water molecules associated with each formula
waters of hydration
the Hsub2O molecules associated with the formula unit of a hydrate
Common hydrate/molecular compound prefixes (1/2 + 1-8)
Hemi=1/2, mono=1, di=2, tri=3,tetra=4, penta=5,hexa=6, hepta=7, octa=8
Naming molecular compounds
step one is identifying it as one (composed of two or more nonmetals)
prefix - name of the first element, prefix-base name of the second element + -ide
Choosing the molecular compound prefix
depends on the number of the subscript behind the element
Acids
molecular compounds that release hydrogen ions (H+) when dissolved in water. characterized by their sour taste and ability to dissolve many metals.
binary acids
composed of hydrogen and a non metal
acids can be catagorized by(2)
binary acids and oxyacids
Naming binary acids
hydro(base name of nonmetal)+ -ic, acid
Naming Oxyacids
- oxyanion ending with -ate
base name of oxyanion + -ic, acid - oxyanion ending with -ite
base name of oxyanion + -ous, acid
Oxyacids contain a
hydrogen and an oxyanion (an anion containing a nonmetal and oxygen)
formula mass
the average mass of a molecule or a formula unit of a compound. found by adding the combine atomic mass of all its constituent atoms. ex COsub2 =12.01amu + 2(16.00)amu = 44.01amu
Molar mass of a compound
the amount of amu found in the formula mass in grams
Mass percent composition or Mass percent
of an element is that elements percentage of the compounds total mass. ex the %mass of oxygen in Hsub2O
combustion analysis
a common (and related) way to obtain empirical formulas for unknown compounds, especially those containing carbon and hydrogen
combustion analysis works by
an unknown compound being burned by oxygen, then the oxygen and burned compound are ran through two Hsub2O and COsub2 absorbers where they are isolated and weighed.
Chemical reaction
process in which one or more substances are converted into one ore more different ones
combustion reaction
a particular type of chemical reaction in which a subsatnce combines with oxygen to form one or more oxygen-containing compounds. emits head
chemical equation
represents a chemical reaction
reactants and products
reactants are on the left, products on the right
balance
both sides of the equation must have the same number of each atom as the other side
