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Pure Substances and Mixtures Notes

Pure Substance: a sample of matter that has unique and definite characteristics

Atoms Vs. Molecules:

An atom is the smallest part of an atom.

When 2 or more atoms are coupled together, they are called molecule.

The difference between atoms and molecules: o Atoms are single (just 1 atom)o Molecules are couples (2 or more atoms)

Sometimes molecules are made of atoms that are the same

Sometimes molecules are made of atoms that are different

When all the particles in something are the same, it is called a pure substance

Elements:

Elements = 1 kind of atom (same type)

Elements are pure

Elements cannot be broken down or separated

Examples:o Oxygen (O) o Hydrogen (H) o Neon (Ne)

Compounds:

Compounds = a molecule with 2 or more elements (different types of atoms) chemically combined

Compounds are pure

Compounds can be separated chemically (through chemical reactions)

Examples:o Water (H 2O)o Salt (NaCl) o Carbon dioxide (CO 2)

Mixtures:

Mixtures are 2 or more elements or compounds that are physically together

Mixtures are not pure

The components of a mixture can be separated physically (you do not need a chemical reaction)

Examples of Mixtures:o Chex mix o Salt water

There are 2 types of mixtures:o homogenous o heterogeneous

Heterogeneous means differento Unevenly mixed throughout the substanceo Examples:

Chex mix pizza soup

Homogenous means sameo Evenly mixed throughout the substanceo Examples:

Kool-Aid Lemonade Tea/coffee Milk