Properties of Matter: Mini-lectures 1 and 2

Pure Substance

s

Mixtures

Element

Compound

Heterogenous

Homogenous (Solution)

Matter (Stuff of the

Universe)

Matter: material which has mass and takes up space (volume)

Pure Substances: matter with the same fixed composition and properties.

Elements: cannot be broken down into simpler substances (every element on the periodic table).

Atom: the smallest particle that still has properties of an element.

Compound: a bonded combination of two or more elements that cannot be separated by physically separated.Molecule: the smallest discrete particle that can still represent a compound (some elements are found in nature as molecules).

Formula Unit: the simplest ratio of ions in an ionic compound.

State of Matter: solid, liquid or gas

Mixture: A physical combination of two or more substances.

Phase: Part of a mixture with the same properties.

Heterogeneous Mixture: A combination of two or more substances that is not the same throughout (i.e. oil and water).

Homogeneous Mixture (Solution): A combination of two or more substances that are uniformly distributed.

Aqueous: A substance dissolved in water.

Chromatography

Decanting

Distillation

Techniques for separating mixtures using the physical properties of the substances

Heterogeneous Mixture

Solution

Physical Properties--a characteristic of matter that exists without changing the matter

examples: melting point, freezing point, physical state (usually at room temperature), volatility, density, volume mass, solubility

Chemical Properties--a characteristic of matter that only exists when changing the matter to another substance

examples: flammability, tendency to corrode, color change, heat or light emission

Properties of Matter

Types of Chemical ChangesDecomposition

reaction which includes the breakdown of more complicated compounds into (new) less complicated compounds or

elements(i.e. composting pile, decaying organisms, Cu Lab Step 3)

Precipitationreaction where a new solid is formed from a mixture of

aqueous solutions (i.e. sugar forms in cooling iced tea, Cu Lab Step 2)Oxidation-Reduction

reactions where electrons are transferred between two substances resulting in new substances

(i.e. rusting or any type of corrosion, Cu Lab Steps 1 and 5)

Physical Change--a change in the physical characteristics of matter which does not result in making a substance with new properties.

Chemical Change--a change in which substances are converted into entirely different substances with different physical and chemical properties

Changes in Matter

Chemical Reaction—any change, physical or chemical in nature; involves reactants and different products, either in state or composition, written as a chemical equation

2H2(g) + O2(g) 2H2O(l)

H2O(g) H2O(l)

Reactants Products

All Chemical Reactions follow the Law of Conservation of Mass: the mass of the reactants will equal the mass of

the products in any non-nuclear reaction.

However, in actuality, some mass will be lost in the experimental process which is performed. The amount

you collect of product, is typically less than that of reactant. SO, a special yield based on the Law of

Conservation of Mass is performed.

Theoretical Yield: The mass of product that should be produced in a reaction. This is based on the mass of the reactants, or on a stoichiometric calculation.

Actual Yield: The mass of product that is formed when the reaction is carried out. This is what is measured in the lab.

Percent Yield: The ratio of the actual process results to the anticipated process results. The percent yield should NEVER be greater than 100%, but it often is calculated as such because of experimental error.

= Percent Yield

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