CHEMISTRY 1/2 Flashcards
What are dispersion forces?
Dispersion forces are weak forces of attraction that occur between instantaneous dipoles.
What causes an instantaneous dipole?
An instantaneous dipole is caused by the constant movement of electrons, which may be found on one side of an atom or molecule at any point in time.
What are induced dipoles?
Induced dipoles are created when an instantaneous dipole causes a shift in the electron distribution in neighboring atoms or molecules.
What factors influence the strength of dispersion forces?
- The number of electrons in the molecules
- The shapes of the molecules
How does the number of electrons affect dispersion forces?
Generally, the more electrons the molecules of a substance have, the stronger the dispersion forces between them.
How do molecular shapes influence dispersion forces?
The shape affects how closely the molecules may approach each other; the closer they can get, the stronger the attraction.
Do all covalent molecular substances have dispersion forces?
Yes, all covalent molecular substances have dispersion forces between their molecules.
What happens in polar molecules regarding intermolecular attraction?
In polar molecules, the positive side of one molecule attracts the negative side of another, creating simultaneous intermolecular attraction.
What is hydrogen bonding?
Hydrogen bonding is a special case of dipole–dipole attraction that occurs when hydrogen bonds to a more electronegative atom.
What happens to hydrogen’s electrons when it bonds to electronegative atoms?
The electrons move toward the more electronegative atom, exposing the positively charged hydrogen nucleus.
What defines a polar molecule?
A polar molecule has one end that is slightly negative and one end that is slightly positive.
What is another term for a polar molecule?
A polar molecule is sometimes called a dipolar molecule or molecular dipole.
Do all polar molecules contain polar bonds?
Yes, all polar molecules contain polar bonds.
Can a molecule have polar bonds and still be non-polar?
Yes, a molecule with polar bonds can be non-polar if the individual dipoles cancel each other out.
What determines the overall polarity of a molecule?
The overall polarity depends on the direction of the bond dipoles in the molecule, determined by the molecule’s shape.
What is the trend of electronegativities within a period? (2 trends)
Electronegativities increase from left to right within a period and decrease from top to bottom. (Due to the atomic radius)
