unit 3: states of matter

when do phase changed occur?

when do phase changed occur?

when the kinetic energy of the particles change

attractive forces between particle

intermolecular

attractive forces within a molecule

intramolecular

unequal sharing of valence electrons between two nonmetals with very different electronegativity values

polar covalent bond

equal sharing of valence electrons between two nonmetals with same or similar electronegativity values

nonpolar covalent bond

transfer of valence electrons from metal to nonmetal

ionic bond

solids have a _____ shape and ______ volume

definite; definite

liquids have a _____ shape and _______ volume

indefinite; definite

gases have a ______ shape and ______ volume

indefinite; indefinite

what are the three types of intermolecular forces?

dipole-dipole, hydrogen, and dispersion

dipole-dipole force occurs between two _____ molecules

polar

in dipole-dipole force, the ________ charge is attracted to a ________ charge

positive charge; negative charge

hydrogen bond occurs between two ____ molecules

polar

when the positive H of a molecule is attracted to the negative F, O, or N atom of another molecule, it’s known as a _______ _______

hydrogen bond

the hydrogen bond is the ______ intermolecular force.

strongest

dispersion force occurs between two ______ molecules

nonpolar

when the _____ end of one molecule is briefly attracted to the ______ end of the other molecule, it is called ________ _____

positive; negative; dispersion force (London)

what happens when molecules briefly collide with each other

electrons of the molecules repel each other and shift, creating a temporary positive and negative ends in the molecules.

what are the three intramolecular forces?

ionic, polar, and covalent

intramolecular forces are stronger than intermolecular forces (true or false)

true

strength of attractive forces (strongest to weakest)

1. ionic

2. polar covalent

3. nonpolar covalent

4. hydrogen bond

5. dipole-dipole force

6. dispersion force

what happens when energy (heat) is added to a substance?

state of matter changes from solid→liquid→gas; particles move faster and farther apart so intermolecular forces get weaker.

endothermic

energy is added

what happens when energy is removed from a substance?

state of matter changes from gas→liquid→solid; particles move slower and closer together so intermolecular forces become stronger.

exothermic

energy is removed

phase change diagram:

weak intermolecular forces= _____ to melt= _____ melting point

easy; low

strong intermolecular forces= ______ to melt= _____ melting point

hard; high

what are the three solids?

crystalline, amorphous, and allotrope

crystalline solids

repeating 3-D pattern called crystal lattice; have regular shapes that reflect the arrangement of the particles.

amorphous

non-crystalline solids; particles not arranged regularly; solid has no definite structure

allotropes

different forms of the same element; different ways atoms bond together

• examples: carbon

  • diamond- arranged in crystal lattice

  • graphite- parallel layers held by dispersion

  • buckminsterfullerene (buckyball)- soccerball

surface tension

property of a liquid that causes the surface to act like weak skin

cohesion

sticking together of particles of the same substance

_______ IM force= ______ surface tension

stronger; higher

surfactant

acts on the surface and interferes with the IM forces between liquid particles, which lowers the surface tension

• examples: soap, detergent, or rubbing alcohol

vaporization

phase change from liquid→gas

evaporation

phase change from l→g at the surface

in evaporation, molecules with ______ kinetic energy at the surface can ______ the liquid. Lower _____ is left therefore it has a lower ______

higher; leave—energy; temperature

when does boiling occur

when liquid is heated to a temperature at which the vapor pressure pushes up and is equal to the atmospheric pressure that pushes down.

______ intermolecular force= ____ energy needed for vapor pressure to overcome atmospheric pressure= ______ boiling point

stronger; more; higher

the behavior of gases is affected by ________ and ________ temperature

pressure; temperature

vacuum

space with no gas particles= no collisions= no pressure