U2S8 Nonmetals and Periodic Table Vocabulary

Vocabulary flashcards covering key terms from the lesson on nonmetals and the periodic table.

Nonmetals

A group of elements characterized by brittleness, low density, poor thermal and electrical conductivity, and a tendency to be volatile and often gaseous at room temperature; their reactivity varies across the periodic table.

Brittle

Easily broken or shattered.

Volatile

Easily transforms into a gas; tends to evaporate easily; many nonmetals are volatile and can be gases at room temperature.

Density

Mass per unit volume.

Thermal insulator

A substance that does not allow heat to pass easily.

Electrical insulator

A substance that does not allow electric current to flow easily.

Halogens

Group 17 elements; highly reactive nonmetals.

Halide

A chemical compound formed with at least one halogen element from group 17.

Group 18

The Noble Gases; a group of almost completely unreactive gases with full outer electron shells.

Noble gases

A set of nonreactive elements in Group 18; have full outer electron shells; used in lighting and other applications.

Valence electrons

Electrons in the outermost shell; influence bonding and reactivity; across a period they increase.

Electron shell distance

Distance of the outer electron shell from the nucleus; increases down a group, making it harder to attract electrons to fill the shell.

Full outer shell / Octet

Outer shell filled with the maximum number of electrons (octet for many elements); leads to stability; noble gases have full shells.

Metalloids

The small middle group of elements with properties between metals and nonmetals.

Metals

The largest group on the periodic table; typically good conductors of heat and electricity; malleable and ductile; form positive ions; reactivity varies by group.

Diatomic molecules

Nonmetals that pair up to form two-atom molecules, such as O2 and Cl2.

Reactivity (nonmetals)

In nonmetals, reactivity generally increases from left to right across a period and decreases down a group.

States of matter for halogens

Halogens are the only group with members in all three states of matter (solid, liquid, gas) at room temperature.