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CORC 1322 MAIN PAGE

MATTER

Introduction
Atoms and Molecules

ATOMIC STRUCTURE

Introduction
Electrons
Protons
Neutrons

REACTIONS

Introduction
Bonds and Octet Rules
Chemical Equations
The Mole

SOLVING PROBLEMS

Density
Conversions

VISUAL AIDS

Functional Groups
Periodic Table

QUIZZES

Practice Quiz I
Practice Quiz II
Practice Quiz III

Atoms and Molecules

Atoms are the basic building blocks of matter, in the same way that bricks are the basic building blocks of a house. Atoms are incredibly small, too small even to be seen with a microscope. There are 9 sextillion atoms (9,000,000,000,000,000,000,000) in a penny.

An atom, magnified approximately 1,000,000,000,000,000,000 times
This is an imaginary construct being used for illustrative purposes.

Atoms can combine with other atoms to form molecules. Molecules always contain more than one atom. Water exists as a molecule, made up of one oxygen atom and two hydrogen atoms.

Molecules can be broken apart into atoms, which are simpler forms of matter. Atoms, however, are among the simplest forms of matter and cannot be broken apart into anything else by ordinary chemical means. Similarly, compounds can be broken down into elements, which are simpler forms of matter; elements cannot be broken down into anything else by ordinary chemical means. If you had a sample of an element, say iron, and divided it an infinite amount of times, you would end up with just a pile of atoms, every one identical to the other.

Representation of atoms in an iron nail

If you had a sample of a compound, like water, and divided it an infinite amount of times, you would end up with a pile of molecules, every one identical to each other. However, you could go a step further and begin to divide the molecules themselves to result in a pile of the different atoms that make up the molecules.

Representation of a water molecule

To summarize, an element, which is matter that cannot be broken down into smaller parts by ordinary chemical means, exists as a collection of atoms. A compound, which is matter that can be broken down into smaller parts, exists as a chemical combination of elements and, in many cases, as a collection of molecules.