Honors Chemistry - Unit 2 Notes: Matter, Changes, Mixtures, and the Periodic Table

Vocabulary flashcards covering classification of matter, physical and chemical changes, separation techniques, and the periodic table based on Honors Chemistry Unit 2 Notes.

Atom

The smallest unit of an element that still has the properties of that element.

Element

A pure substance made of only one type of atom, such as Fe, He, or $O_2$.

Molecule

Two or more atoms chemically bonded together, such as $O_2$, $H_2O$, or $CO_2$. It is not automatically a compound.

Compound

Two or more different elements chemically bonded in a fixed ratio, such as $H_2O$, $CO_2$, or NaCl.

Mixture

Two or more substances physically combined in variable proportions, such as air, salt water, or trail mix.

Diatomic Elements (HOFBrINCl)

Elements that exist bonded as pairs with a subscript $2$ when appearing by themselves: $H_2$, $O_2$, $F_2$, $Br_2$, $I_2$, $N_2$, and $Cl_2$.

Physical change

A change in form, state, or appearance without changing chemical identity, such as melting, freezing, boiling, cutting, crushing, and dissolving.

Chemical change (chemical reaction)

A change that produces one or more new substances by rearranging atoms and changing chemical bonds.

Melting

The phase change from solid to liquid.

Freezing

The phase change from liquid to solid.

Vaporization

The phase change from liquid to gas.

Condensation

The phase change from gas to liquid.

Sublimation

The phase change directly from solid to gas.

Deposition

The phase change directly from gas to solid.

Dissolving

A physical change that occurs when a substance dissolves in water to form an aqueous solution, designated as $(aq)$.

Electrical conductivity

A physical property; testing conductivity does not alter the substance's chemical identity.

Law of Conservation of Mass

A law stating that matter is not created or destroyed in a chemical reaction; the total mass and the number of atoms of each element remain identical before and after a reaction.

Homogeneous mixture

A mixture with uniform composition throughout, also referred to as a solution (examples: air, salt water, vinegar).

Heterogeneous mixture

A mixture with nonuniform composition where different parts or regions can be distinguished (examples: oil and water, salad, sand and water).

Gravity filtration

A separation method that uses filter paper and gravity to separate an insoluble solid from a liquid, yielding a filtrate and residue.

Filtrate

The liquid that passes through the filter paper during gravity filtration.

Residue

The solid left behind on the filter paper during filtration.

Vacuum filtration

A separation technique using suction, a Buchner funnel, filter paper, and a vacuum flask to separate a solid from a liquid, often used when the solid is the desired product.

Distillation

A technique that separates substances based on differences in boiling points via heating, vaporizing, cooling, condensing, and collecting.

Chromatography

A separation technique that separates substances based on differences in how they travel through a stationary material with a moving solvent.

Family / Group

A vertical column on the periodic table; elements in the same family tend to share similar chemical properties.

Period

A horizontal row on the periodic table.

Alkali metals

The elements belonging to Group 1 of the periodic table, excluding hydrogen.

Alkaline earth metals

The elements belonging to Group 2 of the periodic table.

Transition metals

The elements located in Groups 3 through 12 on the periodic table.

Halogens

The elements located in Group 17 of the periodic table.

Noble gases

The elements located in Group 18 of the periodic table.

Metalloids

Elements near the stair-step line separating metals and nonmetals, commonly including B, Si, Ge, As, Sb, and Te.

STP

Standard Temperature and Pressure, typically defined in classroom chemistry as $0\,^\circ\text{C}$ ($273.15\,\text{K}$) and $1\,\text{atm}$.

Liquids at STP

The two elements that exist as liquids under typical classroom STP conditions: $Br_2$ (bromine) and Hg (mercury).