Matter and atomic structure
Francine Taylor-Campbell, Contributor

In this series of lessons we will review briefly the main points for each topic after which we will attempt questions to determine how well the concepts have been understood.

At the end of this TOPIC students should be able to:

• Explain the differences between the three states of matter in terms of energy and particle arrangements.
• State the evidence that supports the particulate nature of matter.
• Describe the structure of atoms.
• Describe the structure of the first 20 atoms.
• State the properties of electrons, protons and neutrons.
• Define atomic number, mass number and relative atomic mass.

Important points

• Matter has mass and occupies space. The quantity of matter in a material is determined by its mass.
• The state that matter occupies depends on how the particles in it are packed.
• The three states of matter are solid, liquid and gas.
• Matter can be changed from one form to another by increasing or decreasing the kinetic energy of the material.
• Processes such as freezing, melting and boiling can change the form that matter takes.
• All substances are made of atoms. These combine to form elements which later form compounds.
• Matter consists of particles which may be atoms, molecules or ions.
• Atom is the smallest part into which an element can be divided.
• An atom consists of three main particles: protons, neutrons and electrons.

How can matter be converted from one form to another?

This is done by changing the kinetic energy of the particles through changes in temperature. For example, let us consider a cube of ice. When the temperature is increased, particles gain energy and will begin to move, changing the regular ordered structure. This represents the process of melting and the ice will change to water.

Further increase in temperature will change the water to steam (gas) as the particles get more energy to move. This is called boiling. To reverse this process one decreases the temperature by cooling (condensation) and freezing. These represent the way in which the states of matter can be changed from one form to the other. Sublimation describes the change directly from solid to gas.

What are the main differences between the three states of matter?

Victor Dixon High School's top students (from left) Shaleen Dias, Jeffrey Pitter, Sashanna McCalla, Tanya Scott, Sheena Drummond and Vashti Clarke. - Photo by Gareth Manning

Francine Taylor-Campbell is an independent contributor. Send questions and comments to kerry-ann.hepburn@gleanerjm.com