We are constantly analyzing and describing the properties of matter. If you have ever compared the colour of two different shirts, you have compared their properties. If you have ever stepped onto a scale to weigh yourself, you have measured a property. If you have ever sniffed a spoonful of food before tasting it, you have used a property to aid in a decision. A property is any attribute of an object. Colour, height, mass, density, smell, taste, temperature and texture are just a few examples of common properties we use on a daily basis.
We can group types of properties into different categories. One way to group types of properties is by the type of information it provides about an object. For example, if I was holding an object behind my back and told you that the object I was holding had a mass of 1.0 Kilograms, would you know what the object was?
You would have no idea what the object was because knowing the mass of the object does not help to determine the identity of the object. A property that depends on the amount of matter and does not depend on the identity of the matter is called an extensive property.
Now, if I was again holding an object in my hand and told you that the object was an orange coloured metal that is a good conductor of electricity, would you know what the object is?
You could probably make a very confident guess that I have a piece of copper in my hand. In this example, the property of colour provided information to help determine the identity of the object. A property that depends on the type of matter and does not depend on the amount of matter is called an intensive property.
To determine the identity of a substance you would need to make some observations of that particular substance. You can make observations like the colour, texture, smell, etc. All of these simple observations would be considered physical properties. A physical property is a quality of a substance that can be observed without changing the composition of the substance.
There are other properties that can help us determine the identity of a substance that would change the composition of the substance. A property that changes the composition of matter is called a chemical property. Examples of chemical properties include ability to burn or ability to dissolve in acid.
Since we are on the topic of changing matter, there are actually two types of changes that matter can undergo. These two changes are called physical changes and chemical changes. A physical change is a change in which the substance is the same type of matter before the change and after the change. An example of this type of change is water melting (water is still water whether it is solid or liquid). A chemical change is a change in which the substance is a different type of matter after the change. An example of this would be burning a piece of paper.
To identify if a physical or chemical change has occured, we can simply look for some evidences of a chemical change.
- A new smell has been produced
- Heat has been produced
- Light has been produced
- A new colour has been produced
- A precipitate has been produced
- A gas has been produced (evident by bubbles)