Covalent bonds in simple molecules, ions & ionic bonding Flashcards
What is valency?
Equal to the number of atoms of H that the atom/group could combine with/displace in forming compounds.
What are valence electrons?
Electrons in the outermost shell.
What is the Octect Rule?
In stable molecules, atoms share valence electrons in the numbers required to achieve filled out shells.
List the important anions
OH- (hydroxide)
CO3 2- (carbonate)
COO- (carboxylate)
NO3 - (nitrate)
NO2 - (nitrite)
PO4 3- (phosphate)
SO4 2- (sulfate)
List the important cations
Na+
K+
Ca+
NH4 +
OH3 + (hydronium)
What is a Lewis structure?
H
|
H - C - H
|
H
What are resonance hybrids?
2 or more possible Lewis structures of a molecule with the same atom positions but differing locations of some electron pairs.
What is bond length?
The distance between the nuclei of two covalently bonded atoms.
What is bond dissociation energy?
The energy required to break the given bond.
How is bond length associated with bond dissociation energy?
In a covalent bond, the 2 atoms are held together as both nuclei are attracted to the same pair of electrons.
Inversely proportional
- longer bond, lower energy as attraction is weaker between nuclei due to distance
What are the properties of ionic bonds?
Conductors
High melting point
What are non-polar covalent bonds?
Electrons shared equally.
No charges on atoms
What are polar covalent bonds?
Electrons shared unequally
(due to electronegativity, so electrons pulled closer to an atom).
Partial charges on atoms
What is an example of a polar molecule?
Water - O more electronegative than H so electrons pulled closer to O.
Resulting in partial - charge.
What is the difference between intermolecular and intramolecular?
Inter - forces that exist between molecules.
Intra - forces holding atoms within a molecule together.
What types of intermolecular forces are there?
Dispersion forces
Dipole-dipole interactions
Steric repulsion
Hydrogen bonds
Hydrophobic forces
What types of intramolecular forces are there?
Ionic interactions
What are dipole-dipole interactions?
Interactions between the - pole of polar molecule and + pole of another molecule.
Permanent, temporary or induced.
What are dispersion forces?
Temp dipoles caused by movement of electrons in a molecule.
- Directly proportional
- More electrons, larger dipole + stronger force
What are hydrogen bonds?
WEAK interaction
H atom covalently bonded to electronegative atom.
H atom can only form a H bond with a lone pair on another electronegative atom.
What is a intermolecular hydrogen bond?
H bond formed between two molucles.
What is a intramolecular hydrogen bond?
H bond formed between two different atoms in same molecule.
What are ionic interactions?
NOT same as ionic bond.
Attractive forces that exist between ionic species.
What is steric repulsion?
Arrangement of atoms in a molecule.
Affects rates + activation energies of most chemical reactions.
What is Van Der Waals?
WEAK interaction
Overall interaction between two molecular species once the dispersion forces + dipolar interactions and steic repulsion force are taken into accout.
