Nonmetals - Key terms
ALLOTROPES:
Different versions of the same element, distinguished by molecular structure.
DIATOMIC:
A term describing an element that exists as molecules composed of two atoms. This is in contrast to monatomic elements.
ELECTROLYSIS:
The use of an electric current to cause a chemical reaction.
HALOGENS:
Group 7 of the periodic table of elements, with valence electron configurations of ns 2 np 5 . In contrast to the noble gases, the halogens are known for high levels of reactivity.
ION:
An atom or group of atoms that has lost or gained one or more electrons, and thus has a net electric charge.
ISOTOPES:
Atoms that have an equal number of protons, and hence are of the same element, but differ in their number of neutrons. This results in a difference ofmass. Isotopes may be either stable or unstable. The unstable type, known as radioisotopes, are radioactive.
METALS:
Elements that are lustrous or shiny in appearance; malleable, meaning that they can be molded into different shapes without breaking; and excellent conductors of heat and electricity. Metals, which constitute the vast majority of all elements, tend to form positive ions by losing electrons.
MONATOMIC:
A term describing an element that exists as single atoms. This in contrast to diatomic elements.
NOBLE GASES:
Group 8 of the periodic table of elements, all of whom (with the exception of helium) have valence electron configurations of ns 2 np 6 . The noble gases are noted for their extreme lack of reactivity—in other words, they tend not to react to, or bond with, other elements.
NONMETALS:
Elements that have a dull appearance; are not malleable; are poor conductors of heat and electricity; and tend to gain electrons to form negative ions. They are thus opposite of metals in most regards, as befits their name. In addition to hydrogen, in Group 1 of the periodic table, the other 18 nonmetals occupy the upper right-hand side of the chart. They include the noble gases, halogens, and seven "orphan" elements: boron, carbon, nitrogen, oxygen, phosphorus, sulfur, and selenium.
ORBITAL:
A pattern of probabilities regarding the position of an electron for anatom in a particular energy state. The higher the principal energy level, the more complex the pattern of orbitals.
RADIOACTIVITY:
A term describing a phenomenon whereby certain isotopes known as radioisotopes are subject to a form of decay brought about by the emission of high-energy particles. "Decay" does not mean that the isotope "rots"; rather, it decays to form another isotope until eventually (though this may take a long time), it becomes stable.
REACTIVITY:
The tendency for bonds between atoms or molecules to be made or broken in such a way that materials aretransformed.
SHELL:
The orbital pattern of the valence electrons at the outside of an atom.
VALENCE ELECTRONS:
Electrons that occupy the highest principal energy level in an atom. These are the electrons involved in chemical bonding.