Classification of Matter and Physical and Chemical Changes Flashcards
What do physical changes not change ?
They do not change the chemical makeup of the sample of matter
What is a physical change?
A change that does not alter the chemical composition of the material and can get the original back
What are some examples of physical changes?
Phase changes, change of color (without chemical change like painting), grinding, tearing, dissolving, etc.
What is a chemical change?
It produces a new substance and can not get the original back
What are some examples of chemical changes?
Rusting of iron, souring of milk, and combustion (burning)
How do we know that a chemical change occurred?
A gas is produced, chemical color change, odor, heat is produced, a precipitate (solid in a liquid) is formed
What is matter broken down into?
Pure Substances and Mixtures
What are pure substances?
Elements and compounds
What is an element?
One type of atom that cannot be broken down by chemical means
What is a compound?
Two or more different types of atoms bonded together that can be broken down by chemical means
What can elements be?
Either atoms or diatomic molecules
What are some examples of elements that are atoms?
Na, K, S, C, Au, Ag, Kr, etc.
What are some examples of elements that are diatomic molecules?
H2, N2, O2, F2, Cl2, Br2, I2
How can compounds be broken down?
Can be broken down into elements by chemical reactions called decomposition
What is a mixture?
A mixture is a physical blend of two or more substances- they can be separated since they are physically mixed
