Periodic Table

ALAKALI METALS

The alkali metals are a group of chemical elements in the periodic table with very similar properties: they are all shiny, soft, silvery, highly reactive metals at standard temperature and pressure[1] and readily lose their outermost electron to form cations with charge +1.[2]:28 They can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation.[1] Because of their high reactivity, they must be stored under oil in sealed glass ampoules to prevent reaction with air.[3] In the modern IUPAC nomenclature, the alkali metals comprise the group 1 elements,[note 1] excluding hydrogen (H), which is nominally a group 1 element[5][6] but not normally considered to be an alkali metal[7][8] as it rarely exhibits behaviour comparable to that of the alkali metals.[9] All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones

THE ALKALINE EARTH METALS

The alkaline earth metals are a group of chemical elements in the periodic table with very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure[1] and readily lose their two outermost electrons to form cations with charge +2.[2] In the modern IUPAC nomenclature, the alkaline earth metals comprise the group 2 elements

ANION 

A negatively charged ion, as one attracted to the anode in electrolysis.

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 nucleus to the boundary of the surrounding cloud of electrons. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius.

CATION

An ion or group of ions having a positive charge and characteristically moving toward the negative electrode in electrolysis.

ELECTRONEGRAVITY

Electronegativity, symbol ?, is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself.[1] An atom's electronegativity is affected by both its atomic number and the distance that its valence electrons reside from the charged nucleus. The higher the associated electronegativity number, the more an element or compound attracts electrons towards it. First proposed by Linus Pauling in 1932 as a development of valence bond theory,[2] it has been shown to correlate with a number of other chemical properties. Electronegativity cannot be directly measured and must be calculated from other atomic or molecular properties. Several methods of calculation have been proposed, and although there may be small differences in the numerical values of the electronegativity, all methods show the same periodic trends between elements.

HALOGENS

The halogens or halogen elements are a series of nonmetal elements from group 17 of the periodic table (formerly: VII, VIIA), comprising fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117 (ununseptium) may also be a halogen.

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INNER TRANSITION METAL

An inner transition metal is a metal in the section of the periodic table that is pulled out from the rest of the table. They include La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr.

ION

An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The word ion is the transliteration of the Greek participle ??? (meaning "going"), and was first used by physicist Michael Faraday for the substances that allow a current to pass ("go") between electrodes in a solution, when an electric field is applied.

IONIZATION ENERGY

The ionization energy of a chemical species, i.e. an atom or molecule, is the energy required to remove electrons from gaseous atoms or ions. The property is alternately still often called the ionization potential, measured in volts. In chemistry it often refers to one mole of a substance (molar ionization energy or enthalpy) and reported in kJ/mol. In atomic physics the ionization energy is typically measured in the unit electron volt (eV). Large atoms or molecules have a low ionization energy, while small molecules tend to have higher ionization energies.

METALLOID

A metalloid is a chemical element with properties that are in-between or a mixture of those of metals and nonmetals, and which is considered to be difficult to classify unambiguously as either a metal or a nonmetal. There is no standard definition of a metalloid nor is there agreement as to which elements are appropriately classified as such. Despite this lack of specificity the term continues to be used in the chemistry literature.

METALS

A substance with high electrical conductivity, luster, and malleability, which readily loses electrons to form positive ions (cations). Metals are otherwise defined according to their position on the Periodic Table, including groupings as alkali metals, alkaline earth metals, transition metals, and rare earth metals.

NOBLE GASES

The noble gases make a group of chemical elements with similar properties: under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn).

NONMETALS

Nonmetal, or non-metal, is a term used in chemistry when classifying the chemical elements. On the basis of their general physical and chemical properties, every element in the periodic table can be termed either a metal or a nonmetal. (A few elements with intermediate properties are referred to as metalloids. 

PERIODIC LAWS

In chemistry, law stating that many of the physical and chemical properties of the elements tend to recur in a systematic manner with increasing atomic number. Progressing from the lightest to the heaviest atoms, certain properties of the elements approximate those of precursors at regular intervals of 2, 8, 18, and 32. For example, the 2d element (helium) is similar in its chemical behavior to the 10th (neon), as well as to the 18th (argon), the 36th (krypton), the 54th (xenon), and the 86th (radon). The chemical family called the halogens, composed of elements 9 (fluorine), 17 (chlorine), 35 (bromine), 53 (iodine), and 85 (astatine), is an extremely reactive family.

REPRESENTATIVE ELEMENTS

An element whose highest occupied s or p sublevels are partially filled. They are the elements in groups 1A-7A in the Periodic Table. They display a wide range of physical and chemical properties

TRANSITION METALS

In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings:

The IUPAC definition[1] states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell".
Most scientists describe a "transition metal" as any element in the d-block of the periodic table, which includes groups 3 to 12 on the periodic table. All elements in the d-block are metals. In actual practice, the f-block is also included in the form of the lanthanide and actinide series.