Chem II: 1-2 Flashcards
(94 cards)
octet rule
atom tends to bond with other atoms so that it has 8 electrons in outermost shell –> forming a stable electron configuration similar to that of noble gases
exceptions to octet rule
incomplete octet
stable with fewer than 8 electrons
H (2), He (2), Li (2), Be (4), B (6)
exceptions to octet rule
expanded octet
any elemet in period 3 and greater can hold more than 8 electrons
exceptions to octet rule
odd numbers of electrons
any molecule with odd number of valence electrons cannot distribute those electrons to give 8 to each atom
ex: NO
atoms that almost always abide by octet rule
C, N, O, F, Na, Mg
nonmetals ____ electrons
gain
metals ____ electrons
lose
ionic bonding
one or more electrons from an atom with low ionization energy (typically metals) are transferred to atom with high electron affinity (typically nonmetals)
resulting in electrostatic attraction between opposite chages
coordinate covalent
if both of shared electrons in covalent bond are contributed by only one of the 2 atoms
difference between ionic and covalent compounds
ionic - gain/loss of electrons
covalent - sharing of electrons
alkali and alkaline earth metals readily form ionic bonds with…
halogens of group VIIA
physical characteristics of ionic compounds
- high MP and BP due to electrostatic attractions
- solubility of ions in water due to interactions with polar solvents
- good conductors of heat and electricity
- crystal lattice arrangement to minimize repulsive forces
- large electronegativity differences between ions
why do ionic bonds tend to form between metals and nonmetals
metals lose electrons because they have low ionization energies
nonmetals gain electrons because they have high electron affiinities
physical characteristics of covalent compounds
- relatively week intermolecular interactions
- lower MP and BP
- poor conductor of electricity bc do not break down into constituent ions
bond length
avg distance between the two nuclei of atoms in a bond
as the number of shared electron pairs increases, bond length ______ bc…
decreases because the two atoms are pulled closer together
bond energy
energy required to break a bond by separating its components into their isolated, gaseous atomic states
the greater the number of pairs of electrons shared between the atomic nuclei, the _____ energy is required to break the bonds holding the atoms together
more
7 common diatomic molecules are:
(make a 7 in periodic table)
H2, N2, O2, F2, Cl2, Br2
dipole moment eq
p = qd
p: dipole moment (debye units –> coulomb meters)
q: magnitude of charge
d: distance
what kinds of rxns are coordinate covalent bonds usually found?
nucleophile-electrophile rxns, lewis acid-base rxns, complexation rxns
nonbonding electrons
electrons in valence shell that are not involved in covalent bonds
bonding electrons
valence electrons involved in a covalent bond
formal charge
assumes equal sharing of all bonded electron pairs




















































