05/14 Intermolecular Forces and Phases of Matter Free Online FlashCards

How are particles arranged in a solid?

In a solid, particles are closely packed and mainly vibrate about fixed positions, giving the solid a definite shape and volume.

What particle behavior defines a liquid?

In a liquid, particles remain close together but can move past one another. A liquid has a definite volume but takes the shape of its container.

Why does a gas have no fixed shape or volume?

In a gas, particles are widely separated and move independently, so a gas has neither a definite shape nor a definite volume.

What causes London dispersion forces?

London dispersion forces arise from temporary uneven electron distributions that induce dipoles in nearby particles. They occur between all atoms and molecules, including nonpolar species.

Which molecules experience dipole–dipole attractions?

Dipole–dipole attractions occur between the partially positive end of one polar molecule and the partially negative end of another.

What conditions produce hydrogen bonding?

Hydrogen bonding occurs when H bonded to N, O, or F is attracted to a lone pair on N, O, or F in a neighboring particle.

What is an ion–dipole attraction?

Ion–dipole attractions occur between an ion and a polar molecule; they help explain how ionic substances dissolve in polar solvents.

How do stronger intermolecular forces affect bulk properties?

Stronger intermolecular attractions generally produce higher boiling points, higher melting points, greater viscosity, and greater surface tension, but lower vapor pressure.

What is viscosity?

Viscosity is a liquid’s resistance to flow. Stronger attractions and more complicated or elongated molecules usually increase viscosity.

Why do liquid droplets tend to be spherical?

Surface tension is the energy required to increase a liquid’s surface area. Surface molecules experience a net inward attraction, so the liquid tends to minimize its surface.

Which equation calculates heat for a phase change?

During a phase change, use q=nΔH, where q is heat transferred, n is moles, and ΔH is the molar enthalpy of the phase change.

Which equation applies to heating within one phase?

Use q=mcΔT for a temperature change within one phase, where m is mass, c is specific heat capacity, and ΔT=Tfinal−Tinitial.