Chemical Bonds and Forces Flashcards
What distinguishes an ionic bond from a covalent bond?
Electron sharing vs electron donation and receiving
What determines how electrons are shared in a covalent bond?
The electronegativity of the atoms
What is electronegativity?
The tendency for an atom to pull electrons towards itself
What is a pure covalent bond?
When the atoms have the same or similar electronegativity, the electrons in the bond are near the centre
What is a polar covalent bond?
When the atoms have different electronegativity, the electrons are closer to the more electronegative atom, which creates a dipole moment
What groups form ionic interactions? What kind of interaction are they?
Electrostatic interactions. They form between two groups with opposite charges
What are the two things required for a hydrogen bond to form?
A polar covalent bond and an electrostatic interaction
What can donate a hydrogen bond?
S-H
O-H
N-H
What can receive a hydrogen bond?
O and N with a free lone pair
What stops an atom that would normally receive a hydrogen bond from receiving one?
Resonance delocalization
Why can a sulfhydryl group donate a hydrogen bond but not receive one?
The sulfur is electronegative enough to allow for a dipole moment, so it can donate a hydrogen bond. But the outer electrons of sulfur have too much energy to receive a hydrogen bond
How are Van der Waals forces formed? How long do they last?
Form from temporary dipole moments in a non-polar bond, from the electrons moving around in the bond. They are very short lived
What are hydrophobic interactions?
Interactions between non-polar groups in a polar environment
Why do non-polar substances aggregate together in a polar environment?
Reduces the surface area that is interacting with the polar environment, which is more favourable
