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