Chemical vs. Physical

Properties, Changes, Reactions, and more!

By: Payton Chronister Pd. 1

Physical Properties

Physical Property- A property that can be observed or measured without changing the composition of matter.  A physical property is what we use to observe and describe matter. Some examples of physical properties are the texture, color, odor, and melting/boiling point of an object or substance. In this picture, a physical property of the Beryllium would be that its color is gray/silver.

Physical Changes

Physical Change- A change that takes place without any changes in molecular composition.  A physical change is basically any kind of change that occurs in matter without changing the chemical composition or make-up of that object or substance.  In a physical change, the same element or compound is present before and after the change, and the same molecules are present throughout the entire change.  Only the form of the object changes in a physical change.  These relate to physical properties because some measurements are needed in order for the changes to be made.  Some examples of physical changes are ice melting to form water, crumpling paper, chopping wood, and breaking glass. This picture shows that crumpled paper is a physical change because even though it looks different, it still has the same chemical properties.

Chemical Properties

Chemical Properties- properties of matter that describe the object's "potential" to undergo a chemical change or reaction by its composition.  Chemical properties are determined by the elements, electrons, and bonding present to give the potential for a chemical change.  Some examples of chemical properties are flammability, reactivity, toxicity, and the ability to combine with other substances.  In this picture, there is a match that is on fire.  There is phosphorus on the tip of the match, and its chemical property of flammability is allowing the match to burn.

Chemical Changes

Chemical Change- the result of a reaction which creates 1 or more substances with different chemical properties. A chemical change results in 1 or more substances that have completely different compositions from the original substances.  The elements/compounds are rearranged into new compounds during a chemical change.  A chemical change changes the composition of the matter.  A few examples of chemical changes are food spoiling, leaves changing color, wood burning, and fireworks exploding.  Here, you can see that there has been a chemical change in the leaves because they have changed colors. 

Chemical Reactions

Chemical Reaction- a process that changes the structure and energy of atoms, molecules, or ions but not their nuclei.  In a chemical reaction, 2 or more substances are combined, and they produce a new substance with different properties. However, unlike chemical changes, the substance created by a chemical reaction still has the same number of particles and atoms before and after the reaction.  In a chemical reaction, the matter is never destroyed; the particles are simply rearranged to a different form, creating a new substance.  Signs that a chemical reaction has occured are a change in temperature, a formation of gas, a release in light or energy, and a change in taste or odor. The picture to the left shows that the reaction betweeen Magnesium and Oxygen releases light.

Reactants and Products

In a chemical reaction, there are reactants and products. Reactants are the substances present before the reaction takes place. These are the things that are there at the start.  Products are the substances formed during a chemical reaction.  These are there at the end.  An example of a chemical reaction is mixing Poly A and Poly B to create Polyurethane Foam.  The reactants in this reaction are Poly A and Poly B, but the product is the foam because it is what was created during the reaction.  A way that you can tell this is a chemical reaction is that the temperature changes.

Law of Conservation of Mass

The Law of Conservation of Mass states that the mass of different substances in a closed system will always be constant, no matter what is happening inside the system.  Basically, this law says that matter can change form, but it cannot be created or destroyed.