Page 9 - Surviving Chemistry BFF Homework Helper and Test Prep Preview

Matter with fixed and definite composition.

Always homogeneous.

Elements and Compounds.

Na (sodium), H2 (hydrogen), NH3 (ammonia)

Substances composed of identical atoms with the
same atomic number.

Cannot be decomposed into smaller substances.

Na (sodium), H2 (hydrogen), Co (cobalt)

Substances composed of two or more different
chemically bonded atoms.

Composition is fixed and definite (can’t be changed).

Can be chemically broken down or decomposed
NH3 (ammonia), NaCl (sodium chloride)

H2O (water), KClO3 (potassium chlorate)

Matter whose composition is not fixed or definite (it
can be varied or changed).

Composed of two or more different substances
physically put together (not bonded).

Can be homogeneous or heterogeneous.

NaCl(aq) (salt solution), NH3(aq), Air, and Soil

Mixtures with a uniform composition throughout.
All samples from the same mixture have the same
mixtures composition.

NaCl(aq) (salt solution) and NH3(aq)

Mixtures with a non-uniform composition.
Samples from the same mixture have different
mixtures compositions.

Atoms in compounds are combined in a fixed and

definite ratio.

The composition of water, H2O, will always be
2H : 1O ratio.

The mass percentages of water will always be
88% O : 12% H
Copyright © 2011. E3 Scholastic Publishing. e3chemistry.com 7