4.1 Compounds, mixtures, and chemical change Flashcards
What is an element?
An element contains only one type of atom.
What is a compound?
A compound is made of atoms of different elements, bonded together.
What is the compound described by?
The compound is described by a formula, made from the symbols of the atoms in it.
What is a mixture?
A mixture contains different substance that are not bonded together.
What is a chemical change?
A chemical change means that a chemical reaction has occured where one or more atoms are removed or added to a molecule.
What is a chemical change usually called?
A chemical change is usually called a chemical reaction.
What are the three signs of a chemical change?
One or more new chemical substances are formed.
Energy is taken in or given out, during the reaction.
The change is usually difficult to reverse.
When is it a physical change?
If no new chemical substance is formed, a change is a physical change. Unlike chemical changes, a physical change is usually easy to reverse.
