CHAPTER 3. STATES OF MATTER AND THE KINETIC MOLECULAR THEORY 3.2
- There are three states of matter: solid, liquid and gas.
- Diffusionis the movement of particles from a high concentration to a low concentra-
tion. Brownian motion is the diffusion of many particles. - Melting pointis the temperature at which asolid changes its phase to become a
liquid. The process is called melting. - Freezing pointis the temperature at which a liquid changes its phase to become a
solid. The process is called freezing. - Evaporation is the process of going from a liquid to a gas. Evaporation from a liquid’s
surface can happen at a wide range of temperatures. - Boiling pointis the temperature at which a liquid changes phase to become a gas.
The process is called evaporation. The reverse process (change in phase from gas to
liquid) is calledcondensing. - Sublimation is the process of going from a solid to a gas.
- Thekinetic theory of matterattempts to explain the behaviour of matter in different
phases. - The kinetic theory of matter says that all matter is composed ofparticleswhich have
a certain amount ofenergywhich allows them tomoveat different speeds depend-
ing on the temperature (energy). There arespacesbetween the particles and also
attractive forcesbetween particles when they come close together.
Chapter 3 End of chapter exercises
1. Give one word or term for each of the following descriptions.
a. The change in phase from a solid to a gas.
b. The change in phase from liquid to gas.
2. Water has a boiling point of 100 ◦C
a. Define boiling point.
b. What change in phase takes place when a liquid reaches its boiling
point?
3. Describe a solid in terms of the kinetic molecular theory.4. Refer to the table below which gives the melting and boiling points of
a number of elements and then answer the questions that follow. (Data
from http://www.chemicalelements.com)Chemistry: Matter and Materials 61