ECM Notes

ELEMENTS (10/31)

element - pure substance that can not be separated into simpler substances by chemical or physical means

Examples:

• Gold (Au)
• Carbon (C)
• Iron (Fe)
• Oxygen (O)

pure substance - a material in which all of the basic particles are identical

basic particles in an element are atoms

Classifying Elements

• Scientists classify by properties
• Physical Properties -- hardness, melting point, density
• Chemical Properties -- flammability, reactivity

Sorting Elements

Metal - shiny, good conductor, malleable, ductile, brittle

Metalloid - shares properties of both metals and nonmetals, semiconductors

Nonmetal - dull, poor conductor, not malleable, not ductile, brittle

COMPOUND (11/1)

Compound - pure substance made of two or more elements that are chemically combined (or bonded)

Examples:

• Table Salt = Sodium (Na) and Chloride (Cl) = NaC
• Water = Hydrogen (H) and Oxygen (O) = H₂O

Different compounds have unique properties. Properties of a compound can be very different from the original elements

• For example sodium (Na) is a very reactive metal and chlorine (Cl) is a green deadly gas. When they chemically combine the create table salt (NaCl) which is yummy on French fries!!!

Elements combine in a variety of ways to create compounds. This depends on amount and types of elements.

• Carbon (C) and Oxygen (O) can combine to form both Carbon monoxide (CO), a deadly gas, and carbon dioxide (CO₂), the substance plants take in for photosynthesis.

You can break a compound apart only be chemical means (electrolysis, fire, reactions, etc...)

MIXTURES (11/2)

Mixture--- two or more substances that are not chemically joined to one another

Examples:

• Vegetable soup
• sugar water
• brass

A mixture is made from different substances that are not chemically joined together - imagine M&Ms which can be mixed together in a packet, but which are not chemically joined to each other.

The different substances in a mixture can be separated from each other without needing a chemical reaction, in the way that different M&Ms can be picked out and put into separate piles.

Homogeneous Mixture

Solutions are homogeneous mixtures or types of mixtures that appear to be a single substance. Homogeneous means the same throughout. The particles in this type of mixture are evenly distributed. Salt water is a solution. Soda is a solution. Steel is also a solution! Steel (a mixture of carbon and iron) and brass (a mixture of zinc and copper) are called alloys or solid solutions. Solutions are always transparent!

Heterogeneous Mixture

These mixtures have larger parts that are different from one another and are unevenly mixed. Sand is an example. A toy box full of toys is also an example. There are two types of special heterogeneous mixtures called suspensions and colloids.

CONCEPT MAP