Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
• an atom tends to bond with other atoms until it has 8 electrons in its outermost shell
• forming a stable electron configuration similar to that of the group VIII (noble gas) |
Octet rule
|
|
|
• H → 2 valence electrons (Helium)
• Li → 2 valence electrons • Be → 4 valence electrons • B → 6 valence electrons • P and S → more than 8 valence electrons by incorporating d orbitals |
Exception to the octet rule
|
|
|
• an electron(s) from an atom with a smaller ionization energy is transferred to an tom with a greater electron affinity
• results in positive (cation) and negative ion (anion) • ions held together by electrostatic forces • difference in electronegativity must be 1.7 • b/w metals and non-metals • Na+ Cl- |
ionic bonding (electrovalent bonding)
|
|
|
• an electron pair is SHARED between two atoms
• binding results from attraction that each electron of the shared pair has for the two positive nuclei |
covalent bonding
|
|
|
• a partially covalent and partially ionic bond
|
polar covalent bond
|
|
|
• high melting and boiling pts (bc of high electrostatic forces b/w ions)
• conduct electricity • form crystal lattices (maximize attractive forces between oppositely charged ions, minimize repulsive forces between similarly charged ions |
physical properties of ionic compounds
|
|
|
• can share more than one electron pair
• low-melting solids • do not conduct electricity • characterized by bond length and bond energy |
properties of covalent bonds
|
|
|
• the number of shared electron pairs between two atoms
•single bond (bond order of one) •double bond (bond order of two) •triple bond (bond order of three) |
bond order
|
|
|
• the average distance between the two nuclei of the atoms involved in a bond
• ↑ # of shared electron pairs, pulls atoms together, decreasing bond length • triple bond is shorter than double bond, double bond is shorter than single bond |
bond length
|
|
|
• the energy required to separate two bonded atoms
• the strength of a bond (bond energy) ↑ as the number of share electron pairs increases |
bond energy
|
|
|
C-C longest bond length, weakest
C=C medium bond length, medium C≡C shortest bond length, strongest |
bond length and strength
|
|
|
• shared valence electrons of a covalent bond
|
bonding electrons
|
|
|
• valence electrons not involved in the covalent bond
|
nonbonding electrons
|
|
|
• unshared electron pairs
|
lone electron pairs
|
|
|
• FC = (number of valence electrons of the atom in isolation) - (number of lone pair electrons on this atom in the molecule) - 1/2 (total number of electrons participating in covalent bonds with this atom in the molecule)
|
formal charge equation
|
|
|
• contributes to stability
• lower the overall charge of molecule ↑ stability • negative formal charges on more electronegative elements ↑ stability |
formal charge
|
|
|
• the representation of a compound by two or more canonical structures in which the valence electrons are rearranged to give structures of similar probability
• The actual structure is considered to be a hybrid |
resonance structure
|
|
|
• occurs between atoms with small differences in electronegativity (0.4 to 1.7 pauling units)
• unequal sharing of bonding electrons, pulled toward more electronegative element • more electronegative element has partial negative charge (δ-) and less electronegative element has partial positive charge (δ+) |
polar covalent bond
|
|
|
• a molecule that has separation of positive (δ+) and negative (δ-) charges
|
polar molecule
|
|
|
1. polar covalent bond
2. nonpolar covalent bond 3. coordinate covalent bond |
3 types of covalent Bonding
|
|
|
• the vector product (u) of the charge magnitude (q) and the distance between the two partial charges (r)
• denoted by an arrow from positive to the negative charge • measured in Debye units (coulomb meters) |
dipole moment
u = qr |
|
|
• type of covalent bonding between atoms of the same electronegativity
• bonding electron pair is shared equally (no separation of charge) • occurs in diatomic molecules (H2, cl2, o2, n2) |
nonpolar covalent bond
|
|
|
• type of covalent bond
• the shared electron pair comes from the lone pair of one of the atoms in the molecule • typically found in lewis acid-base compound |
coordinate covalent bond
|
