Chapter 3: Bonding and Chemical Interactions Flashcards
When you have two or more atoms with similar electronegativities interacting, how do the electrons interact to form an ion?
Complete transfer of electrons
Which is greater…energy required to form covalent bond or energy released upon formation of ionic bond?
Energy required to form ions through covalent bonding
energetically unfavorable to create ions
What are the intermolecular interactions like between covalent compounds?
Discrete molecular units with relatively weak intermolecular interactions resulting in lower melting and boiler points and poor conductivity
What is bond order? Explain the three common ones.
the number of shared electron pairs between two atoms
Single bond = bond order of 1
Double bond = bond order of 2
Triple bond = bond order of 3
What three factors characterize a covalent bond?
bond length, bond energy, and polarity
What is bond length?
Average distance between two nuclei of atoms in a bond
How does the number of shared electron pairs affect the bond length?
As the number of shared electron pairs increases, the two atoms are pulled closer together resulting in a decreased bond length
Which of the bonds is shortest? Longest?
[Single, double, triple]
Longest: Triple
Middle: Double
Shortest: Single
What is bond energy?
The energy required to break a bond by separating its components into their isolated atomic states
How does the number of shared electron pairs affect the bond energy?
The greater the number of pairs of electrons shared between the atomic nuclei, the more energy is required to break the bonds holding the atoms together
What is polarity?
When two atoms have a relative difference in electronegativity
How does electronegativity effect electron density in covalent bonds?
The atom with the higher electronegativity gets the larger share of the electron density
Which end of the dipole is the less electronegative atom? More electronegative atom? (positive vs negative)
Less electronegative atom is the positive end
More electronegative atom is the negative end
How are electrons shared between two molecules with nearly identical electronegativities?
There is an equal distribution of electrons
What is a nonpolar covalent bond?
No separation of charge across the bond due to differences in electronegativity
Which bonds can exhibit a purely equal distribution of electrons?
Only bonds between atoms of the same element therefore they have the same electronegativities
What is a polar covalent bond?
Atoms that differ moderately in their electronegativities that share electrons unevenly
What must be the difference in electronegativity to be considered a covalent bond?
Between 0.5 and 1.7
What must be the difference in electronegativity to be considered a polar covalent bond? Nonpolar?
Between 0.5 and 1.7 for polar
Between 0 and 0.5 for nonpolar
How and what is the distribution of charge for polar covalent bonds?
The more electronegative element acquires a great portion of the electron density becoming a partial negative (δ− ) and the less electronegative electron acquires a smaller portion of the electron density taking on a partial positive charge (δ+)
What is dipole moment and what are the units?
Measure of the polar bond or molecule as a vector quantity and is measured in Debye units (C*m)
What is a coordinate covalent bond?
Both of the shared electrons originated on the same atom (a long pair from one atom attacked another atom)
What is a coordinate covalent bond?
Both of the shared electrons originated on the same atom (a long pair from one atom attacked another atom’s unhybridized p orbital)
What is a Lewis acid? a Lewis base?
Lewis acid is any compound that will accept a lone pair of electrons
Lewis base is any compound that will donate a pair of electrons to form a covalent bond?
[nucleophile/electrophile]
What type of “bond” are Lewis acids and bases found in?
Coordinate covalent bond
Which shell are bonding electrons found in for covalent bonds?
They are found in the valence shell
What is formal charge and how do you find it?
The hypothetical charge that would result if all bonding electrons are shared equally across a covalent bond
(#VE it should have) - (#VE in bonded atom in respect to equal sharing of electons)
What is oxidation state and how do you find it?
The hypothetical charge that would result if all bonding electrons are assigned to the more elctronegative atom in the bond
(#VE it should have) - (#VE in bonded atom in respect to elecronegativity)
What is oxidation state and how do you find it?
The hypothetical charge that would result if all bonding electrons are assigned to the more elctronegative atom in the bond
(#VE it should have) - (#VE in bonded atom in respect to elecronegativity)
What is it called if you can draw Lewis structures for a particular compound that differ only in the arrangement of the electron pairs?
Resonance
How do you determine which arrangement may be most likely if there are several resonance forms?
The arrangement that minimizes the formal charge and magnitude of formal charge is usually most stable
In respect to resonance structures, what is the actual arrangement of the electrons in the compound?
It would be a hybrid of all the possible resonance structures
Which elements have an exception to the octet rule?
all elements in and beyond the third period because they take on more than eight electrons in their valence shells being placed into the d subshell
