Get started!

  • Stage 1

    Answer 5 out of 7 questions correctly.

Matter can exist in different physical states, like solid, liquid, and gas. The solid, liquid, and gas states of water all have the same chemical composition: each consists of
H
2
O
molecules. Yet, the states have different properties. So what controls whether a substance like water exists as a solid, liquid, or gas?
Two competing factors, intermolecular forces and kinetic energy, determine a substance's physical state.
  • Intermolecular forces (IMFs) like hydrogen bonds, dipole-dipole forces, and London dispersion forces hold particles together. Intermolecular forces within a substance are strongest when the average distance between individual particles is small.
  • Kinetic energy is the energy of motion of a substance's particles. As temperature increases, kinetic energy increases, and particles move faster and farther apart. Particles with enough kinetic energy may move fast enough to overcome their intermolecular forces and transition from one state to another.
Use the particle models to compare the kinetic energy and intermolecular forces of the solid, liquid, and gas states of water at constant pressure. The motion lines illustrate a molecule's relative kinetic energy. Molecules with more motion lines have a higher kinetic energy than molecules with fewer motion lines.
Determine whether each statement is true or false.
True
False
Water vapor has stronger IMFs than liquid water.
Water vapor has a higher average kinetic energy than solid ice.
As temperature increases, the average kinetic energy of the water molecules decreases.
The strength of IMFs decreases as the distance between water molecules increases.
ref_doc_title.

Confetti

Jumping to stage 1 of 1

Excellent!

Now entering the Challenge Zone—are you ready?

Teacher tools