Chemistry Unit 1: Matter, Properties, and Changes

Vocabulary flashcards covering atomic theory, classification of matter, laws of proportions, physical and chemical properties and changes, and physical separation techniques.

Law of Definite Proportions

A law stating that a specific compound will always have the same percent by mass for each element (the same ratio).

Percent by Mass

The percentage that each element (partial mass) makes up in a compound (total mass), calculated as $\text{\% by mass} = \frac{\text{partial (element)}}{\text{total (compound)}} \times 100$.

Law of Multiple Proportions

A law stating that when two or more elements combine to form different compounds, they do so in whole number ratios.

Mixture

Two or more substances combined physically.

Homogeneous Mixture

A mixture that is evenly distributed throughout (also called a solution), such as salt water or air.

Heterogeneous Mixture

A mixture that is unevenly distributed throughout, such as concrete, milk, or sand and water.

Filtration

A physical separation technique that separates solid particles from a liquid.

Chromatography

A physical separation technique that separates pigments (colors) based on polarity.

Evaporation

A physical separation technique that separates a dissolved solid from a liquid solvent.

Distillation

A physical separation technique that separates mixtures of liquids.

Extraction

A physical separation technique that separates components based on different solubilities.

Centrifugation

A physical separation technique that rapidly spins mixtures to separate components.

Physical Separation Techniques

Methods used to physically separate components of mixtures based on their physical properties.

Element

A pure substance that cannot be separated into simpler substances by chemical or physical means.

Dimitri Mendeleev

The chemist who was the first to design the periodic table in 1869, organizing elements by mass and reactivity.

Compound

A substance composed of two or more elements combined chemically (bonded) that can be broken down into its components by chemical means such as electrolysis.

Physical Change

A change in appearance where no chemical reaction is involved, such as phase changes, solubility, breaks, or expected color changes.

Endothermic

A process or reaction in which heat/energy is absorbed (heat in).

Exothermic

A process or reaction in which heat/energy is released (heat out).

Chemical Change

A change in which a reaction occurs and a new substance forms, evidenced by heat change, light, pH change, explosion, or gas formation.

Law of Conservation of Mass

A law stating that mass is the same before and after a chemical reaction and cannot be created or destroyed ($\text{Mass}_{\text{reactants}} = \text{Mass}_{\text{products}}$).

Matter

Something that takes up space.

Substance

Matter that has a definite composition that does not change.

Plasma

An ionized ("charged") gas state of matter, examples including lightning and the sun.

Bose-Einstein Condensate

A state of matter occurring near absolute zero where there is no particle movement.

Absolute Zero

The theoretical temperature at which there is no particle movement, defined as $0\,\text{Kelvin}$ or $-273^\circ\text{C}$.

Physical Properties

Observable properties that do not affect reactivity, such as color, mass, volume, density, size, taste, solubility, and melting or boiling point.

Chemical Properties

Properties of a substance that affect its reactivity, such as combustibility and oxidizability.

Extensive Properties

Properties that change depending on the amount of substance present, such as volume, mass/weight, and moles.

Intensive Properties

Properties that do not change with the amount of substance present, such as density, color, composition, taste, smell, and all chemical properties.