periodic table
metalliods
A metalloid is a chemical element with properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid, nor is there complete agreement as to which elements are appropriately classified as such.
alkali metal
Alkali metals are the chemical elements found in Group 1 of the periodic table. The alkali metals include: lithium, sodium, potassium, rubidium, cesium, and francium.
inner transition
An inner transition metal is one of a group of chemical elements on the periodic table. They are normally shown in two rows below all of the other elements. They include elements 57-71 (lanthanides) and 89-103 (actinides). The lanthanides are very similar, and the actinides are all radioactive.
electronegativity
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative at 0.7.
metals
In chemistry, a metal is an element that readily forms positive ions (cations) and has metallic bonds. Metals are sometimes described as a lattice of positive ions surrounded by a cloud of delocalized electrons.
nonmetals
In chemistry, a nonmetal (or non-metal) is a chemical element that mostly lacks metallic attributes.
valence electron
In chemistry, a valence electron is an electron that is associated with an atom, and that can participate in the formation of a chemical bond; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair.
transition metal
In chemistry, the term transition metal (or transition element) has two possible meanings: The IUPAC definition defines a transition metal as "an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell".
ionic radii
Ionic radius, rion, is the radius of an atom's ion. Although neither atoms nor ions have sharp boundaries, they are sometimes treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.
noble gases
Noble gas, noble gas [Credit: Encyclopædia Britannica, Inc.]any of the seven chemical elements that make up Group 18 (VIIIa) of the periodic table. The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and element 118 (temporarily named ununoctium [Uuo]).
representative element
The Representative Elements are those elements within the first two families (Groups I and II on the far left) and the last six families or groups (on the right) of the Periodic Table. The Transition Metals are the elements in those Groups within the middle of the Table.
earth metals
The alkaline earth metals are six chemical elements in column (group) 2 of the Periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).
atomic radius
The atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding cloud of electrons.
cation and anion
The electronic configuration of many ions is that of the closest noble gas to them in the periodic table. An anion is an ion that has gained one or more electrons, acquiring a negative charge. A cation is an ion that has lost one or more electrons, gaining a positive charge.
halogens
The halogens or halogen elements (/ˈhælɵdʒɨn/) are a group in the periodic table consisting of five chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117 (ununseptium) may also be a halogen.
ionization energy
The ionization energy (IE) is qualitatively defined as the amount of energy required to remove the most loosely bound electron of an isolated gaseous atom to form a cation.
