#36 Elements, Compounds, and Mixtures

There are three main classes of matter:
- Elements
- Compounds
- Mixtures

Elements are pure chemical substance consisting of one type of atom. Substances that are elements are those found on the periodic table of elements (i.e. copper, silver, gold, hydrogen, etc.).Some element occur naturally in nature, by themselves (copper silver, gold, and sulfur), while others are not found in nature, but in chemical compounds (hydrogen, sodium, and potassium). They are found in nature but with other chemicals.

Interesting facts:
- The most commonly occurring element on Earth is iron
- Second most commonly found element on Earth is hydrogen

A compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. The majority of pure substances on Earth are compounds, rather than elements. Compounds CAN be chemically separated into each component. Elements cannot be separated (no ordinary chemical means can separate elements into different substances), and mixtures do not need to be chemically separated.

A mixture is a substance consisting of two or more substances mixed together (not in fixed proportions and not with chemical bonding). In a mixture, each substance keeps their own identity, and properties. Unlike the fixed percentages of a compound, the amounts of each substance in a mixture can vary. There are two different types of mixtures, homogeneous, and heterogeneous. A homogeneous mixture is a mixture that is uniform throughout, each sample that is taken from the substance, has the same ratio of each component (i.e. salt water). A heterogeneous mixture is a mixture in which the ingredients are not uniformly dispersed (i.e. Chicken soup). They differ from region to region in both composition and properties.

1. What is the majority of pure substances found on Earth?
a) Elements
b) Compounds
c) Mixtures
2. What is the most commonly found element found on the Earth?
a) Hydrogen
b) Iron
c) Sodium
d) Oxygen
3. What is the difference between mixtures and compounds?
a) Compounds are chemically combined, while mixtures aren’t
b) Wait…. There is a difference?
c) Mixtures are chemically combined, while compounds aren’t
4. Chicken soup is an example of
a) An element
b) A compound
c) A heterogeneous mixture
d) A homogeneous mixture

For Further Practice put the following items into the different Categories:

Word Bank:
Salt water
Chicken soup
A Package of skittles


Heterogeneous Mixture
Homogeneous Mixture

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