Science / Periodic Table of Elements Glossary

Actinide: Elements 89-102 are called actinides. Electrons added during the Aufbau construction of actinide atoms go into the 5f subshell. Actinides are unstable and undergo radioactive decay. The most . . . View Full Definition

Actinium (Ac): Atomic number: 89, Atomic mass: 227 g.mol -1, Electronegativity: 1.1, Density: 10.07 g.cm-3 at 20°C, Melting point: 1050 °C, Boiling point: 3250 °C, Vanderwaals radius: unknown, Ionic radius . . . View Full Definition

Alkali Metal: The Group 1 elements, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr) react with cold water for form strongly alkaline hydroxide solutions, and are re . . . View Full Definition

Alkaline Earth: An oxide of an alkaline earth metal, which produces an alkaline solution in reaction with water.

Alkaline Earth Metal: The Group 2 elements, beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra) form alkaline oxides and hydroxides and are called 'alkaline earth metals'.

Aluminum (Al): Atomic number: 13, Atomic mass: 26.98154 g.mol -1, Electronegativity: 1.5, Density: 2.7 g.cm -3 at 20 °C, Melting point: 660.4 °C, Boiling point: 2467 °C, Vanderwaals radius: 0.143 nm, Ionic . . . View Full Definition

Americium (Am): Atomic number: 95, Atomic mass: (243) g.mol -1, Electronegativity: unknown, Density: 13.67 g.cm-3 at 20°C, Melting point: 994 °C, Boiling point: 2607 °C, Vanderwaals radius: unknown, Ionic r . . . View Full Definition

Amphoteric: A substance that can act as either an acid or a base in a reaction. For example, aluminum hydroxide can neutralize mineral acids ( Al(OH)3 + 3 HCl = AlCl3 + 3 H2O ) or strong bases ( Al(OH)3 . . . View Full Definition

Antimony (Sb): Atomic number: 51, Atomic mass: 121.75 g.mol -1, Electronegativity: 1.9, Density: 6.684 g.cm-3, Melting point: 631 °C, Boiling point: 1380 °C, Vanderwaals radius: 0.159 nm, Ionic radius: 0.2 . . . View Full Definition

Argon (Ar): Atomic number: 18, Atomic mass: 39.948 g.mol -1, Electronegativity: unknown, Density: 1.78.10 -3 g.cm -3 at 0 °C, Melting point: -189 °C, Boiling point: -185.7 °C, Vanderwaals radius: 0.192 . . . View Full Definition

Arsenic (As): Atomic number: 33, Atomic mass: 74.9216 g.mol -1, Electronegativity: 2.0, Density: 5.7 g.cm-3 at 14°C, Melting point: 814 °C (36 atm), Boiling point: 615 °C (sublimation), Vanderwaals radius . . . View Full Definition

Astatine (At): Atomic number: 85, Atomic mass: (210) g.mol -1, Electronegativity: 2.2, Density: unknown, Melting point: 302 °C, Boiling point: 337 °C (estimation), Vanderwaals radius: unknown, Ionic radius . . . View Full Definition

Atomic Mass: The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus. Atomic mass is measured in Atomic Mass Units (amu) which are scaled relative to carbon, 12C, . . . View Full Definition

Atomic Number: The number of protons in an atom. Each element is uniquely defined by its atomic number.

Atomic Radius: One half the distance between nuclei of atoms of the same element, when the atoms are bound by a single covalent bond or are in a metallic crystal. The radius of atoms obtained from covalent . . . View Full Definition

Atomic Weight: Atomic weight values represent weighted average of the masses of all naturally occurring isotopes of an element. The values shown here are based on the IUPAC Commission determinations (Pure . . . View Full Definition

Barium (Ba): Atomic number: 56, Atomic mass: 137.33 g.mol -1, Electronegativity: 0.9, Density: 3.5 g.cm-3 at 20°C, Melting point: 725 °C, Boiling point: 1640 °C, Vanderwaals radius: 0.222 nm, Ionic radiu . . . View Full Definition

Berkelium (Bk): Atomic number: 97, Atomic mass: (247) g.mol -1, Electronegativity: unknown, Density: 14 g.cm3 at 20°C, Melting point: unknown, Boiling point: unknown, Vanderwaals radius: unknown, Ionic radi . . . View Full Definition

Beryllium (Be): Atomic number: 4, Atomic mass: 9.01218 g.mol -1, Electronegativity: 1.5, Density: 1.86 g.cm-3, Melting point: 1280 °C, Boiling point: 2970 °C, Vanderwaals radius: unknown, Ionic radius: unkn . . . View Full Definition

Bismuth (Bi): Atomic number: 83, Atomic mass: 208.9804 g.mol -1, Electronegativity: 1.9, Density: 9.80 g.cm-3 at 20°C, Melting point: 271 °C, Boiling point: 1420 °C, Vanderwaals radius: 0.152 nm, Ionic ra . . . View Full Definition

Block: A region of the periodic table that corresponds to the type of subshell (s, p, d, or f) being filled during the Aufbau construction of electron configurations.

Bohrium (Bh): Atomic number: 107, Atomic mass: 262 g.mol -1, Electronegativity: unknown, Density: unknown, Melting point: unknown, Boiling point: unknown, Vanderwaals radius: unknown, Ionic radius: unknow . . . View Full Definition

Boron (B): Atomic number: 5, Atomic mass: 10.81 g.mol -1, Electronegativity: 2.0, Density: 2.3 g.cm-3 at 20°C, Melting point: 2076 °C, Boiling point: 3927 °C, Vanderwaals radius: 0.098 nm, Ionic radius . . . View Full Definition

Bromine (Br): Atomic number: 35, Atomic mass: 79.904 g.mol -1, Electronegativity: 2.8, Density: 3.1 g.cm-3 at 20°C, Melting point: - 7.2 °C, Boiling point: 58.8 °C, Vanderwaals radius: 0.165 nm, Ionic rad . . . View Full Definition

Cadmium (Cd): Atomic number: 48, Atomic mass: 112.4 g.mol -1, Electronegativity: 1.7, Density: 8.7 g.cm-3 at 20°C, Melting point: 321 °C, Boiling point: 767 °C, Vanderwaals radius: 0.154 nm, Ionic radius: . . . View Full Definition

Page: 1 2 3 4 5 6