Chapter 10 - Chemical Bonding Flashcards
Bonding Theories
models that predict how atoms bond together to form molecules
Lewis Model
electrons are represented as dots and dot/lewis structures as molecules
Valence Electrons
electrons in the outermost principal shell
-most important in bonding
Lewis Structure/Dot Structure
symbol of element with surrounding dots to represent valence electrons
Octet
8 dots/valence electrons
-stable
Duet
2 dots/valence electrons
-for He, its a stable electron config
Chemical Bond
- sharing/transfer of electrons
- if shared, then it is COVALENT
- if it is transferred, it is IONIC
Octet Rule
in chem bonding, atoms transfer or share electrons to obtain outer shells w 8 electrons
-except H + He
Bonding Pair
electrons that are shared bw 2 atoms
Lone Pair
electrons that are NOT shared
Double/Triple Bond
shorter/stronger than a single bond
Terminal Atoms
at the ends
-H are always terminal
Expanded Octets
can form for period 3 elements and beyond.
ex)SF6 - sulfur has 12 e- surrounding it instead of 8
PCl5 - P has 10 e- surrounding it
Resonance Structure
set of 2 or more lewis structures that describe the polyatomic bonding of a species.
in nature, resonance hybrids are found which are intermediates of all the resonance structures.
VSEPR THEORY
valence shell electron pair repulsion
based on the idea that electron groups (lone pair, single bond, multiple bonds) repel each other
-repulsion bw neg charges determines the geometry of the molecule
Electron Geometry
the geometrical arrangement of the electron groups lone pairs, single bond, and multiple bonds
-even though molecular geometry does not include electrons/lone pairs in their model, the atoms are still placed bc the electron/lone pair still exerts its influence
Molecular Geometry
geometrical arrangement of the atom
single and multiple bonds; does NOT take into consideration lone pairs
Representing bonds on paper
1 Straight Line - bond in plane of paper
2 Hashed Lines - bond is projecting into paper
3 Wedge - bond is projecting out of paper
Major Molecular Geometry Shapes (5)
1 Linear 2 Bent 3 Trigonal Planar 4 Trigonal Pyramidal 5 Tetrahedral
Electronegativity
the ability of an element to attract electrons w/in a covalent bond
ex) O is more electronegative than H, which means that shared e-‘s are more likely to be found near O
Dipole Moment
separation of charge within the bond due to uneven electron sharing
Polar Covalent Bonds
covalent bonds that have a dipole moment
Electronegativity Trend on Periodic Table
Left to Right -Increasing electronegativity
Top to Bottom - decreasing electroneg
Pure Covalent Bond
nonpolar
if two elements have identical electronegativities, then they share electrons equally
- electronegativity difference = 0-0.4
- no dipole moment, nonpolar
Ionic Bond
if the electronegativity is so different bw two elements, like metal + nonmetal, then e-‘s are completely transferred
- electronegativity difference = 2.0+
- bond is ionic
Polar Covalent Bond
If there is an intermediate electronegativity different between 2 elements, like bw 2 nonmetals, the bond is polar covalent
-electronegativity difference = 0.4-2.0
Polar Molecule
one w polar bonds that add together - not cancel each other - to form net dipole moment
- if diatomic molecules contain a polar bond, then they are POLAR
- molecules of different elements’ polarity depends on its shape
Dipole Vector representation
-the arrows/vectors point towards the negative pole, and have a positive sign on towards the positive pole
- if arrows point in exactly opposing directions, then the dipole moment CANCELS
- if the arrows point towards the same direction, then it is a POLAR MOLECULE
Polar Bond
a bond is polar if two bonding atoms have different electronegativities
Polar Shapes
- trigonal pyramidal
- bent
Nonpolar Shapes
- linear
- trigonal planar
- tetrahedral
The octer rule states that chem compounds tend to form o that each atom has an octet of e-s in ___-
the highest occupied energy level
When the octet rule is satisfied, the outermost ____ are filled.
s and p orbitals
That the boiling point of water (H2O) is higher than the boiling point of hydrogen sulfide (H2S) is partially explained by
hydrogen bonding
Electron Groups
1 single bond
2 double bond
3 triple bond
4 lone pair (aka nonbonding pairs)
