Unit B: Chemistry

 Learning Targets

Unit B Background Information


The particle model of matter was introduced in the Grade 7 unit Heat and Temperature, and was also discussed in the Grade 8 unit  Mix and Flow of Matter.

Do you remember the four main points that describe the structure of matter?
  • All matter is made of tiny particles.  Each substance has its own unique particles.

  • Particles are always moving and vibrating.  Particles move differently in a solid, a liquid, or a gas.

  • Particles may be attracted to each other or they may bond together.

  • Spaces occur between the particles.  The amount of space between particles is different in a solid, a liquid, or a gas.

Figure 1 – The three  states of matter. Image courtesy Siyavula Education.

Interactive


In Grades 7 and 8, you were introduced to the three states of matter.
For review, please watch the BrainPOP video called the "States of Matter". When you have finished watching the video, try some of the other interactive activities on this page.

Click here to visit "States of Matter" on the BrainPOP website.

You will need a username and password to access the video:
  • Username: 0099
  • Password: students

Watch

These videos present useful overviews of the particle model of matter. View the videos about the particle theory of matter:

Watch the 7Dc Particle Model of Matter, demonstrated by a junior high class.

 
 
A particles crash course:



Figure 2 – The classification of matter. Image courtesy Siyavula Education.

Figure 3 – Gelatin looks like a pure substance, but it is a mixture of several ingredients.

In the Grade 8 unit, Mix and Flow of Matter, you learned that matter can be divided into two distinct categories: a mixture or a pure substance.

  • When two or more substances are combined, a mixture is produced. 
  • To identify the properties of each of the substances is difficult after they have combined in a mixture. 
  • A pure substance has only one type of matter and it has a unique set of properties. 
  • Examples of pure substances are the elements named on the periodic table.

Watch

ScienceMan explains Elements vs. Compounds:

 
 
The classification of matter:

 
 



 Mixtures can be divided further into two categories:  homogeneous and heterogeneous.

  • A homogeneous mixture appears as if it is only one substance. 
  • Homogeneous mixtures can be solutions, colloids, or suspensions. 
  • At times, differentiating a homogeneous substance from a pure substance is difficult. A cup of tea looks like a pure substance, for example, but we know it has tea leaf particles, and perhaps sugar, dissolved in it.
  • Further testing might be required.
  • A heterogeneous mixture is easy to identify because the various particles are all visible – such as the dry mix for chocolate chip cookies.

Watch

View the following videos explaining the difference between the terms homogenous and heterogeneous.

ScienceMan explains Mixtures:

 
 
Homogenous and Heterogeneous Mixtures:


Now that you have refreshed your memory, you are ready to continue your journey into the science of chemistry.