Different versions of the same element, distinguished by molecular structure.
A term describing an element that exists as molecules composed of two atoms. This is in contrast to monatomic elements.
The use of an electric current to cause a chemical reaction.
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.
An atom or group of atoms that has lost or gained one or more electrons, and thus has a net electric charge.
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.
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.
A term describing an element that exists as single atoms. This in contrast to diatomic elements.
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.
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.
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.
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.
The tendency for bonds between atoms or molecules to be made or broken in such a way that materials aretransformed.
The orbital pattern of the valence electrons at the outside of an atom.
Electrons that occupy the highest principal energy level in an atom. These are the electrons involved in chemical bonding.
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