Unit 3 Flashcards
chemical bond
mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together
ionic bonding
chemical bonding that results from the electrical attraction between large numbers of cations and anions
covalent bonding
sharing of electron pairs between two atoms
nonpolar covalent bond
a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge
polar covalent bond
covalent bond in which the bonded atoms have an unequal attraction for the shared electrons
molecule
a neutral group of atoms that are held together by covalent bonds
octet rule
chemical compounds tend to form so that each atom, by gaining, losing, or sharing electrons, has an octet of electrons in its highest occupied energy level
molecular compound
a chemical compound whose simplest units are molecules
chemical formula
the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts
molecular formula
shows the types and numbers of atoms combined in a single molecule of a molecular compound
diatomic molecule
molecule containing only two atoms
bond length
the distance between two bonded atoms at their minimum potential energy, that is, the average distance between two bonded atoms
bond energy
the energy required to break a chemical bond and form neutral isolated atoms
electron-dot notation
an electron-configuration notation in which only the valence electrons of an atom of a particular element are shown, indicated by dots placed around the element’s symbol
unshared pair/lone pair
pair of electrons that is not involved in bonding and belongs exclusively to one atom
lewis structures
formulas in which atomic symbols represents nuclei and inner-shell electrons, dot-pairs, or dashes between 2 atomic symbols to represent electron pairs in covalent bonds, and dots adjacent to only one atomic symbol represent unshared bonds
structural formula
the kind, number, arrangement, and bonds but not the unshared pairs of the atoms in a molecule
single bond
a covalent bond produced by the sharing of one pair of electrons between two atoms
resonance
bonding in molecules or ions that cannot be correctly represented b y a single Lewis structure
ionic compound
composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal
formula unit
the simplest collection of atoms from which an ionic compound’s formula can be established
C & C a chemical formula for a molecular compound with one for an ionic compound.
- most ionic compounds exist as crystalline solids, a three-dimensional network of positive and negative ions mutually attracted to one another
- in contrast to a molecular compound, an ionic compound is not composed of independent, neutral units that can be isolated and examined; the chemical formula of an ionic compound represents the simplest ratio of the compound’s combined ions that gives electrical stability
List and compare the distinctive properties of ionic and molecular compounds.
- difference in strength of attraction between basic units of molecular and ionic compounds gives rise to different properties in two types of compounds
- melting point, boiling point, hardness of compound dpeend on how strongly basic units are attracted to each other; molecular compounds have low melting and boiling point, ionic compounds have higher melting and boiling points, do not vaporize @ room temperature
- ionic compounds are hard but brittle (difficult to move one row of ions)
Write the Lewis structure for a poly atomic ion given the identity of atoms combined and other appropriate information.
- poly atomic ion: charged group of covalently bonded atoms
- if ion is negatively charged, add the total number of valence electrons to number of electrons corresponding to ion’s negative charge. if ion is positively charge,d subtract the total number of valence electrons a number of electrons corresponding to the ion’s positive charge
crystal lattice
in an ionic crystal, ions minimize their potential energy by combining in an orderly arrangement known as a crystal lattice
lattice energy
the energy released when one mole of an ionic crystalline compound is formed from gaseous ions
metallic bonding
the chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons
malleability
ability of a substance to be hammered or beaten into thin sheets
ductility
ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire
heat of vaporization
metallic bond strength varies with the nuclear charge of the metal atoms and the number of electrons in the metal’s electron sea.
molecular polarity
uneven distribution of molecular charge
Explain VSEPR theory.
“valence-shell, electron-pair repulsion”, repulsion between pairs of valence electrons of the atoms in a molecule
-repulsion between sets of valence-level electrons surrounding an atom causes these sets to be oriented as far apart as possible
Explain how the shapes of molecules are accounted for by hybridization theory.
b
Describe dipole-dipole forces, H bonding, induced diploes, and London dispersion forces.
c
Explain what determines molecular polarity.
d
hybridization
the mixing of two or more atomic orbitals of similar energies on the same atom to produce new orbitals of equal energies
hybrid orbitals
orbitals of equal energy produced by the combination of two or more orbitals on the same atom
inter molecular forces
forces of attraction between molecules
dipole
a dipole is created by equal but opposite charges that are separated by a short distance; strongest intermolecular forces exist between polar molecules, acting as tiny dipoles b/c of uneven charge distribution
dipole-dipole forces
forces of attraction between polar molecules
hydrogen bonding
the intermolecular force in which a hydrogen atom that is bonded to a highly electronegative atom is attracted to an unshared pair of electrons of an electronegative atom in a nearby molecule
london dispersion forces
the intermolecular attractions resulting from the constant motion of electrons and the creation of instantaneous dipoles
monatomic ions
ions formed from a single atom
binary compounds
compounds composed of two different elements
oxyanions
poly atomic ions that contain oxygen
salt
an ionic compound composed of a cation and the anion from an acid
oxidation numbers
in order to indicate the general distribution of electrons among the bonded atoms in a molecular compound or poly atomic ion, oxidation numbers/states are assigned to atoms composing the compound or ion.
formula mass`
the formula mass of any molecule, formula unit, or ion is the sum of the average atomic masses of all the atoms represented in this formula
percentage composition
the percentage by mass of each element in a compound
empirical formula
consist of the symbols for the elements combined in a compound, with subscripts showing the smallest whole-number mole ratio o the different atoms in the compound
Explain the significance of a chemical formula.
a
Determine the formula of an ionic compound formed between two given ions.
b
Name an ionic compound given its formula.
c
Using prefixes, name a binary molecular compound from its formula.
d
Write the formula of a binary molecular compound given its name.
ef
List the rule for assigning oxidation numbers.
f
Give the oxidation number for each element in the formula of a chemical compound.
g
Name binary molecular compounds using oxidation numbers and the Stock system.
h
Calculate the formula mass or molar mass of any given compound.
j
Use molar mass to convert between mass in grams and amount in moles of a chemical compound.
y
Calculate the number of molecules, formula units, or ions in a given molar amount of a chemical compound.
j
Calculate the percentage composition of a given chemical compound.
n
