Topic 4 Bonding Flashcards
(27 cards)
What is an allotrope?
An allotrope occurs when an element can exist in different crystalline forms, such as carbon, which can exist as graphite, buckminsterfullerene, and diamond.
Why is diamond exceptionally hard?
Diamond is exceptionally hard because there is no plane of weakness in the molecule made up of sp3 hybridized carbon atoms.
What hybridization do carbon atoms have in graphite?
In graphite, the carbon atoms are sp2 hybridized.
What is the significance of remaining electrons in graphite?
The remaining electrons after the three σ bonds are delocalized, making graphite an excellent lubricant and a good conductor of electricity.
What factors determine bond length and strength?
Bond length and strength depend on the strength of attraction that two nuclei have for the shared electrons.
How does bond polarity arise?
Bond polarity is caused by a difference in electronegativity between the elements. The greater the difference, the greater the polarity.
What is a pi bond?
A pi bond is a radial bond formed by the sideways overlap of p orbitals with electron densities concentrated above and below a line drawn through the two nuclei.
How many pi bonds are in double and triple bonds?
Double bonds have one π bond, while triple bonds have two π bonds which are perpendicular to each other.
What is a sigma bond?
A sigma bond is an axial bond formed by the head-on overlap of atomic orbitals from two different atoms along the line drawn through the two nuclei.
What is a covalent bond?
A covalent bond is formed by the sharing of electrons, which are attracted by both nuclei, resulting in a directional bond between two atoms.
What is a dative bond?
A dative bond is a bond in which both electrons come from one of the atoms, also known as a coordinate bond.
What characterizes an ionic bond?
An ionic bond is formed by the transfer of electrons from one atom to another to form ions with complete outer shells, resulting in a strong lattice structure.
What is required for a substance to conduct electricity?
A substance must possess electrons or ions that are free to move to conduct electricity.
What is delocalization in chemistry?
Delocalization is the sharing of a single electron pair by more than two atoms.
What are dipole-dipole forces?
Dipole-dipole forces are permanent electrostatic forces of attraction between polar molecules, stronger than van der Waals forces.
What occurs during hydrogen bonding?
Hydrogen bonding occurs when hydrogen is bonded directly to a highly electronegative element (N, F, or O), and it is stronger than dipole-dipole forces.
What are van der Waals forces?
Van der Waals forces are temporary dipole forces due to momentary unevenness in the spread of electrons, and they are the weakest of intermolecular forces.
What is the first step in formal charge theory?
If the compound is covalent, treat the entire molecule; if ionic, treat each ion separately.
What is the formula for calculating formal charge?
F = V – (n + b/2), where V is valence electrons, n is electrons in lone pairs, and b is electrons shared as bonds.
What is hybridization in chemistry?
Hybridization is the combination of orbitals to create new orbitals that are more energetically feasible for bonding.
What is the bond angle of sp3 hybridized bonds?
The bond angle of sp3 hybridized bonds is approximately 109.5°.
What is a Lewis structure?
A Lewis structure is a diagram showing the arrangement of electrons in a molecule, usually only showing valence shells.
What characterizes metallic bonding?
In metallic bonding, the valence electrons in metals become detached and form a ‘sea’ of delocalized electrons around a lattice of positive ions.
What determines molecular polarity?
Molecular polarity depends on both bond polarity and the symmetry of the molecule.
