Bonding and chemical interactions

Electrostatic force

The attraction of protons to electrons

Bond length

Distance b/w 2 nuclei at the point of minimum energy/ where the attractive and repulsive forces cancel each other out

Covalent

A bond formed by atoms sharing electrons

What explains polarity

Separation of charges where one atom is slightly positive and the other is slightly negative due to differences in electronegativity

Where does virtually even sharing of electrons occur

Non polar covalent bond

Ionic bond

A bond formed by the transfer of electrons from one atom to another

What does Coulomb’s law measure

The amount of energy that exists in an ionic bond at a given distance

Coulomb’s Law formula

E= (2.31 x 10^-19 J•nm) (q1 q2/r)

What do ionic bonds usually look like?

Crystals

What are general characteristics of ionic bonds

Generally soluble in water; once separated it can conduct electricity- salt bridge

What are general characteristics of covalent bonds

Tend to be softer solids or liquids or gases; not soluble in water- if they are, they don’t conduct electricity

What makes a polar molecule

Asymmetrical electron distribution around the molecule, geometrical asymmetry, a dipole moment

What causes an asymmetrical electron distribution around a molecule

Differences in EN between 0.5-1.6

What is a dipole moment

An area that is more positive and an area that is more negative on a molecule

What are Lewis structures for

covalent bonding

How do you calculate formal charge

= valence e- dots-sticks

What kind of bond is formed when two atoms are bonded and have an EN difference of 2 or greater?

An ionic bond

What does VSEPR allow you to do

Predict the shape of a molecule

london dispersion forces

a type of van der waals interaction by which molecules exhibit mutual attraction bc of instantaneous dipoles induced by momentary distortions in the electron clouds around the molecules

when do london dispersion forces tend to be more pronounced

in large molecules with large, more polarizable electron clouds

Intermolecular forces

are interactions between molecules and are weaker than INTRAmolecular interactions

How do intermolecular forces help us

they allow us to make predictions about how substances behave

What is the weakest INTERmolecular force

london dispersion

what is the 2nd weakest INTERmolecular force

dipole-dipole

dipole-dipole INTERmolecular force

occurs bw stable (non-transient) dipoles; there is an attractive force bw the (+) dipole of one polar molecule and the (-) dipole of another molecule

What is the 3rd weakest INTERmolecular force

hydrogen bond

hydrogen bond INTERmolecular force

occurs when an H attached to a N, O, or F is attracted to the lone pair on a N, O, or F; very EN with strong dipoles with H

What is the 4th weakest INTERmolecular force?

Ion-dipole

Ion-dipole INTERmolecular force

occurs bw ions and molecules with a dipole, occures bw two molecules with a FULL CHARGE; Eg, peptide hormone bonded to a receptor

What is the strongest INTERmolecular force

Ionic

What is the relationship bw INTERmolecular forces and melting and boiling points

the stronger the intermolecular forces a compound has, the higher its melting and boiling points

INTRAmolecular attractions

connect atoms within a molecule

what are the INTRAmolecular attraction types

Covalent bond and Ionic bonds

nonpolar covalent bond

have equal sharing bw atoms

polar covalent bonds

have unequal sharing bw atoms; similar to an ionic bond bc it is an intermediate between covalent and ionic bonding; has asymmetrical electron distribution and geometrical asymmetry, and a dipole moment

Van der waals forces

INTERmolecular weak electrostatic forces that attract neutral molecules to one another; dependent on the distance between atoms or molecules, but not dependent on temperature; are short range forces, the closer the atoms/molecules are to each other the stronger the force; included dipole-dipole, london dispersion, and hydrogen bonds

What do multiple bonds formed by s and p orbitals consist of

one sigma bond and one or more pi bonds

bond dissociation energy

the total energy required to break the sigma bond and any pi bonds; after a sigma bond is made, the energy increases with each addnl pi bond