Properties of Matter

Before Video

• Matter is anything that has weight and takes up space. Solids, liquids and gases are all forms of matter.

• You encounter many solids, liquids and gases daily. Common liquids include water, milk or juice. Air is a mixture of different gases like oxygen, nitrogen and carbon dioxide. Common solids include pencils, paper, foods and clothing.

• A pencil is a solid object made of wood, carbon, rubber and metal. It is brittle (breakable), floats (and is therefore less dense than water) and is not soluble (does not dissolve in water). A sheet of paper is solid, not magnetic and not soluble. A metal fork is solid, magnetic, not soluble and more dense than water.

• When two substances are combined, they could form a new substance. The properties of the combination needs to be observed to determine if a new substance has been formed.

After Video

• Zoe knew that iron is magnetic and sodium is not so she tested each with a magnet.

• Sodium metal reacts with water causing an explosion.

• Sulfur hexafluoride is more dense than air. When placed inside a balloon, the balloon falls to the ground. Helium is less dense than air. A helium-filled balloon floats in air. A boat filled with air floats on top of Sulfur hexafluoride gas.

• Although other gases could be burned for cooking in BBQ grills, propane gas is easily compressible into tanks.

• Metal conducts heat, which means that it might cause your hand to be burned if used as the handle of a pot. Plastic is a better choice because it does not conduct heat as well as metal.

• Swiss cheese is too soft to be an effective material for a knife and fork. It squishes rather than cuts. Stainless steel is hard and strong. It is even better than iron because iron rusts.

• Magnetism: whether or not a material sticks to a magnet. Density: whether a material floats or sinks in water or air. Solubility: whether or not a material dissolves in water. These are all properties that can be used to describe solid, liquid and gases.

• There are many answers to this question. Here are some examples:
  
  Liquid water is non-magnetic and non-conductive. It is used for drinking, washing dishes and watering plants.
  
  Water in the gas phase is also non-magnetic and non-conductive. It has a much lower density than liquid water. It is used for powering steam engines and some power plants.
  
  Water in the solid phase (ice) is also non-magnetic and non-conductive. Surprisingly, it has a slightly lower density than liquid water. This is a unique property of ice and it is the reason that ice floats on water. If it didn't, all the fish in a frozen lake would get crushed! Ice is used to build igloos, keep food cold and to reduce swelling if you have an injury.

• Knowing the properties of matter can help engineers pick the right types of materials for the job.