The Classification of Matter

PURE SUBSTANCE Something that cannot be broken down into simpler matter using only physical methods. There are two kinds of pure substances… Elements & Compounds.

ELEMENTS  Are the simplest kind of pure substance.  There are ~ 110 elements but 92 occur in nature. Each is made of a different type atom.

 Each element has its own atom!

Not all elements are equally common.

 Most elements are built of individual atoms (ex. Fe, Cu): But a few gaseous elements exist as diatomic molecules. Diatomic Gases Hydrogen H 2 Nitrogen N 2 Oxygen O 2 Fluorine F 2 Chlorine Cl 2 Bromine Br 2 Iodine I 2

COMPOUNDS  Are pure substances that are composed of atoms of 2 or more different elements, chemically bonded to one another due to the transfer or sharing of valence electrons.  Compounds can only be made or broken down by chemical reactions.

COMPOUNDS  Have exact or definite compositions given by a chemical formula (ex. NaCl or H 2 O).  We call the building blocks of compounds molecules!

COMPOUNDS  The properties of compounds are very different from the properties of the elements that make them up!

2Na + Cl 2  2NaCl

MIXTURES A mixture is something that CAN be broken down into simpler materials using physical methods, not chemical reactions. Each part of a mixture keeps its own identity! There are 3 possible types of mixtures: 1)Element + Another Element 2)Compound + Another Compound 3)Element + Compound

MIXTURES There are two types of mixtures: a)Homogeneous- The parts are distributed evenly (dissolved) at the particle level. Every sample is the same. Examples: Salt water; syrup; air; brass.

MIXTURES Homogeneous mixtures are also called solutions. Homogeneous mixtures of solidmetallic atoms are called alloys.

MIXTURES b) Heterogeneous- The parts are not evenly mixed, to the eye and even under a microscope. Every sample is different! Examples: Spaghetti and Meatballs; water + oil mixture, blood.

We learned that the properties of compounds are TOTALLY DIFFERENT from the properties of the elements that make them up. By contrast, the properties of mixtures ARE very much related to the properties of the substances that make the mixtures up. Properties of Saltwater

Matter Flowchart MATTER Can it be physically separated? Homogeneous Mixture Solutions + Alloys Heterogeneous MixtureCompoundElement MIXTUREPURE SUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes

Methods of Mixture Separation 1)Mechanical Separation

Methods of Mixture Separation 2) Magnetic Separation

Methods of Mixture Separation 3) Density Separation: More dense components sink.

Methods of Mixture Separation 4) Centrifuge: Circular motion helps denser components sink.

Methods of Mixture Separation 5) Decant: Pour off a liquid.

Methods of Mixture Separation 6) Filter: A screen lets the small particles through, but traps big particles.

Methods of Mixture Separation 7) Evaporation: Boil off a liquid, leaving a solid behind.

Methods of Mixture Separation 8) Distillation: Evaporate a liquid, and then condense it later.

Methods of Mixture Separation 9) Paper chromatography: Use to separate solutions, since liquids have different attractions to paper.

Four different molecules: Which are compounds?

What are each of these? Atom, Element, Molecule, or Compound

Practice with Vocabulary:

Pure Substance or Mixture?

Single Chemical Formula: All pure substances can be represented by a H2OH2O If it’s really a pure substance, you should only need to write ONE chemical formula to describe it’s composition.

Distillation

Vacuum Filtration Electrolysis