General Chemistry Ch 3. Bonding and Chemical Interactions Flashcards
Chemical bonding general
Formed via the interaction of the valence electrons of the combining atoms, can be ionic or covalent, elements typically form bonds to attain a noble gas like electron configuration
Octet rule
Elements will be the most stable with eight valence electrons, some exceptions including incomplete octets, expanded octet, and odd number of electrons
Ionic bond
Formed by the transfer of one or more electrons from an element with relatively low ionization energy to an element with a relatively high electron affinity, occurs between elements with large differences in electronegativity (usually a metal and non metal), electrostatic attraction between ions causes them to remain in close proximity, electrons not shared, stronger than covalent bonds
Cation
Positively charged ion, loses electrons from neutral to become cation
Anion
Negatively charged ion, gains electrons from neutral to become anion
Crystalline lattices
Large, organized arrays of ion formed by ionic compounds, repeating rows of cations and anions, maximizes forces between oppositely charged ions and minimizes forces between the same ions
Ionic compounds
Unique physical and chemical properties, tend to dissociate in water and other polar solvents, tend to have high melting points, when in molten or aqueous states are good conductors of electricity
Covalent bond
Formed by the sharing of electrons between two elements of similar electronegativities (usually nonmetals), characterized as nonpolar or polar, weaker than ionic bonds
Bond order
The number of shared electron pairs between two atoms, determines whether a covalent bond is a single bond, double bond, or triple bond, as bond order increases bond strength increases, bond energy increases, and bond length decreases
Bond strength
Increases with bond order
Bond energy
Increases with bond order, the energy required to break a bond by separating its components into their isolated, gaseous atomic states
Bond length
Decreases with bond order, the average distance between the two nuclei of atoms in a bond
Nonpolar bonds
Resulting molecules in which both atoms have exactly the same electronegativity, some bonds are considered non-polar when there’s a very small difference in electronegativity
Polar bonds
Form when there is a significant difference in electronegativity’s but not enough to transfer electrons and form ionic bonds, electrons shared unevenly, the more electronegative element takes on a partial negative charge, and the less electronegative element takes on a partial positive charge, creates a dipole
Coordinate covalent bonds
Result when a single atom provides both bonding electrons while the other atom does not contribute any, coordinate covalent bonds are most often found in Lewis acid base chemistry
Lewis dot symbols
Chemical representation of an atoms valance electrons
Formal charges
Exist when an atom is surrounded by more if you were valance electrons and it has and it’s neutral state (assuming equal sharing of electrons in a bond)
Resonance structures
Represent all of the possible configurations of electrons, stable and unstable, that contribute to the overall structure, exist for any molecule with a pi system of electrons
Valance shell electron pair repulsion (VSEPR) theory
Predicts the three-dimensional molecular geometry of covalently bonded molecules, electrons in this theory, whether bonding or non-bonding, arrange themselves to be as far apart as possible from each other in three-dimensional space leading to geometric cute trees
Non bonding electrons VSEPR
Exert more repulsion than bonding electrons because they reside closer to the nucleus
Electronic geometry
Refers to the position of all electrons in a molecule
Molecular geometry
Refers to the position of only the bonding pairs of electrons in a molecule
Polarity of molecules
Is dependent on the diaper moment of each bond and the sum of the dipole moment in the molecular structure, polar molecules contain polar bonds, nonpolar molecules may contain nonpolar bonds or polar bonds that cancel each other out
Sigma bonds
The result of head to head overlap
Pi bonds
The result of the overlap of two parallel electron cloud densities
Intermolecular forces
Electrostatic attraction between molecules, they are significantly weaker than covalent bonds
London dispersion forces
The weakest interactions, but are still present in all atoms and molecules, as the size of the atom or structure increases so does the corresponding London dispersion force
Dipole dipole interactions
Occur between oppositely charged ends of polar molecules, are stronger than London forces, these interactions are evident in the solid and liquid phases but negligible in the gas phase due to the distance between particles
Hydrogen bonds
Specialized subset of dipole dipole interactions involved an intra-and intermolecular attraction, hydrogen bonding occurs when hydrogen is bonded to one of the three very elect electronegative atoms: fluorine, oxygen, nitrogen
Incomplete octet
Elements that do not follow octet rule because they are stable with fewer than 8 electrons in their valence shell and include H, He, Li, Be, and B
Expanded octet
Elements that do not follow octet rule because they can hold more than 8 electrons by incorporating d orbitals, includes any element in period 3 or greater
Odd numbers of electrons
Molecules that cannot follow octet rule because they cannot distribute electrons in a way where all atoms involved have 8 valence electrons
Covalent compounds
Tend to have lower melting and boiling points, do not break down into constituent ions, are poor conductors of electricity in liquid or aqueous states
Partial negative charge
Characteristic of the more electronegative element in a polar covalent bond
Partial positive charge
Characteristic of the less electronegative element in a polar covalent bond
Dipole moment equation
p = q*d
p - the dipole moment
q - the magnitude of the charge
d - the displacement vector separating the two partial charges
Bonding electrons
Electrons involved in a covalent bond in the valance shell
