INTERMOLECULAR ATTRACTIONS (FORCES)

What is a dipole

molecule w/ PARTIAL positive end of a molecule and the PARTIAL negative end . (keep solids & liquids together)

What is London dispersion

1. When charges are unevenly distributed temporarily bsc of random motion of electrons

2. happens to polar & nonpolar

Chart of electronegativity

 

Ionic bond	Greater than 2.0	One atom removes the electron from the other atom
Polar covalent bond	Between 0.4 and 2.0	One atom pulls shared electrons stronger than the other
Nonpolar covalent bond	Same electronegativity	Electrons are shared

Van der Waals forces

collective name for intermolecular forces: 

• London dispersion

• Dipole interactions 

Intermolecular bonds vs ionic & covalent

Intermolecular forces are weaker than ionic and covalent bonds. 

What are the weakest of intermolecular forces

Van der Waals forces are the weakest of intermolecular forces.

What do intermolecular forces determine?

1. states of the matter

2. physical properties of matter ( melting point & boiling point)

How are intermolecular bonds overcome

when heat is added (eg melting ice)

Why doesn’t liquid have a definite shape

the intermolecular forces between the liquid molecules are weaker,

what does polarize mean

to distort the electron cloud of an atom (to form a dipole)

Poles

the oppositely charged ends in an atom. 

relationship btw electrons and London dispersion force

number of electrons in a molecule increases, the London dispersion force increases.

london dispersion (smaller vs larger molecular attraction)

Smaller molecules have a weaker strength of intermolecular attraction due to London dispersion forces than for larger molecules. 

what is London dispersion responsible for?

the weak attraction between diatomic molecules of the halogens

 instantaneous dipole.

This partial charge on the molecule (polar or nonpolar and temporary)

 induced dipole

a dipole is created by a dipole in another molecule.

similarity btw induced and instanetous dipole

 weak and short–lived. bonds

permanent dipole

unequal sharing of electrons in its bonds

-btw POLAR substances

-liquid at room temp

dipole-dipole

the attractive force that occurs between two molecules that both have permanent dipoles,

pemranent dipole vs diatomic nonpolar

pemranent dipole have higher boiling point diatomic nonpolar

What is the strongest intermolecular force

HYDROGEN BONDING

hydorgen bond

when hydrogen is attached to electronegative atom like (nitrogen, oxygen, Floruine)

WHat types of bonds are considered nonpolar

C-H bonds

VOLATILITY

measure of how easily a liquid evaporates.

-The stronger the intermolecular forces, the lower the volatility. 

how does boiling point increase

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