Glossary / Science

Periodic Table of Elements Glossary

Actinide: Elements 89-102 are called actinides. Electrons added during the Aufbau construction of actinide ato
Actinium (Ac): Atomic number: 89, Atomic mass: 227 g.mol -1, Electronegativity: 1.1, Density: 10.07 g.cm-3 at 20°C
Alkali Metal: The Group 1 elements, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and fran
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
Aluminum (Al): Atomic number: 13, Atomic mass: 26.98154 g.mol -1, Electronegativity: 1.5, Density: 2.7 g.cm -3 at 2
Americium (Am): Atomic number: 95, Atomic mass: (243) g.mol -1, Electronegativity: unknown, Density: 13.67 g.cm-3 at
Amphoteric: A substance that can act as either an acid or a base in a reaction. For example, aluminum hydroxide
Antimony (Sb): Atomic number: 51, Atomic mass: 121.75 g.mol -1, Electronegativity: 1.9, Density: 6.684 g.cm-3, Melt
Argon (Ar): Atomic number: 18, Atomic mass: 39.948 g.mol -1, Electronegativity: unknown, Density: 1.78.10 -3 g.c
Arsenic (As): Atomic number: 33, Atomic mass: 74.9216 g.mol -1, Electronegativity: 2.0, Density: 5.7 g.cm-3 at 14
Astatine (At): Atomic number: 85, Atomic mass: (210) g.mol -1, Electronegativity: 2.2, Density: unknown, Melting po
Atomic Mass: The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus. At
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 sin
Atomic Weight: Atomic weight values represent weighted average of the masses of all naturally occurring isotopes of
Barium (Ba): Atomic number: 56, Atomic mass: 137.33 g.mol -1, Electronegativity: 0.9, Density: 3.5 g.cm-3 at 20°
Berkelium (Bk): Atomic number: 97, Atomic mass: (247) g.mol -1, Electronegativity: unknown, Density: 14 g.cm3 at 20
Beryllium (Be): Atomic number: 4, Atomic mass: 9.01218 g.mol -1, Electronegativity: 1.5, Density: 1.86 g.cm-3, Melti
Bismuth (Bi): Atomic number: 83, Atomic mass: 208.9804 g.mol -1, Electronegativity: 1.9, Density: 9.80 g.cm-3 at 2
Block: A region of the periodic table that corresponds to the type of subshell (s, p, d, or f) being filled
Bohrium (Bh): Atomic number: 107, Atomic mass: 262 g.mol -1, Electronegativity: unknown, Density: unknown, Melting
Boron (B): Atomic number: 5, Atomic mass: 10.81 g.mol -1, Electronegativity: 2.0, Density: 2.3 g.cm-3 at 20°C,
Bromine (Br): Atomic number: 35, Atomic mass: 79.904 g.mol -1, Electronegativity: 2.8, Density: 3.1 g.cm-3 at 20°
Cadmium (Cd): Atomic number: 48, Atomic mass: 112.4 g.mol -1, Electronegativity: 1.7, Density: 8.7 g.cm-3 at 20°C
Calcium (Ca): Atomic number: 20, Atomic mass: 40.08 g.mol -1, Electronegativity: 1.0, Mass volume: 1.6 g.cm-3 at 2
Californium (Cf): Atomic number: 98, Atomic mass: (251) g.mol -1, Electronegativity accordin to Pauling: unknown, Dens
Carbon (C): Atomic number: 6, Atomic mass: 12.011 g.mol -1, Electronegativity: 2.5, Density: 2.2 g.cm-3 at 20°C
Cerium (Ce): Atomic number: 58, Atomic mass: 140.12 g.mol -1, Electronegativity: 1.1, Density: 6.76 g.cm-3 at 20
Cesium (Cs): Atomic number: 55, Atomic mass: 132.9054 g.mol -1, Electronegativity: 0.7, Density: 1.9 g.cm-3 at 20
Chlorine (Cl): Atomic number: 17, Atomic mass: 35.453 g.mol -1, Electronegativity: 3.0, Density: 3.21*10 -3 g.cm -3
Chromium (Cr): Atomic number: 24, Atomic mass: 51.996 g.mol -1, Electronegativity: 1.6, Density: 7.19 g.cm-3 at 20
Cobalt (Co): Atomic number: 27, Atomic mass: 58.9332 g.mol -1, Electronegativity: 1.8, Density: 8.9 g.cm-3 at 20
Congener: 1. Elements belonging to the same group on the periodic table. For example, sodium and potassium are
Copper (Cu): Atomic number: 29, Atomic mass: 63.546 g.mol -1, Electronegativity: 1.9, Density: 8.9 g.cm-3 at 20°
Curium (Cm): Atomic number: 96, Atomic mass: (247) g.mol -1, Electronegativity: unknown, Density: 13.51 g.cm-3 at
Darmstadtium (Ds): Atomic number: 110, Atomic mass: 261.9 g.mol -1, Electronegativity: unknown, Density: unknown, Melti
Dubnium (Db): Atomic number: 105, Atomic mass: 261.9 g.mol -1, Electronegativity: unknown, Density: unknown, Melti
Dysprosium (Dy): Atomic number: 66, Atomic mass: 162.50 g.mol -1, Electronegativity: 1.2, Density: 8.6 g.cm-3 at 20°
Einsteinium (Es): Atomic number: 99, Atomic mass: 254 g.mol -1, Electronegativity: unknown, Density: unknown, Melting
Electron Configuration: The distribution of electrons according to the energy sublevels (subshells) in uncharged atoms. The
Erbium (Er): Atomic number: 68, Atomic mass: 167.26 g.mol -1, Electronegativity: 1.2, Density: 9.2 g.cm-3 at 20°
Europium (Eu): Atomic number: 63, Atomic mass: 167.26 g.mol -1, Electronegativity: 1.2, Density: 9.2 g.cm-3 at 20°
Fermium (Fm): Atomic number: 100, Atomic mass: (257) g.mol -1, Electronegativity: unknown, Density: unknown, Melti
First Ionization Energy: The energy needed to remove an electron from an isolated, neutral atom.
Fluorine (F): Atomic number: 9, Atomic mass: 18.998403 g.mol -1, Electronegativity: 4, Density: 1.8*10-3 g.cm-3 at
Francium (Fr): Atomic number: 87, Atomic mass: (233) g.mol -1, Electronegativity: 0.7, Density: unknown, Melting po
Gadolinium (Gd): Atomic number: 64, Atomic mass: 157.25 g.mol -1, Electronegativity: 1.1, Density: 7.9 g.cm-3 at 20°
Gallium (Ga): Atomic number: 31, Atomic mass: 69.72 g.mol -1, Electronegativity: unknown, Density: 5.1 g.cm-3 at 2
Germanium (Ge): Atomic number: 32, Atomic mass: 72.59 g.mol -1, Electronegativity: 1.8, Density: 5.3 g.cm-3 at 20°C
Gold (Au): Atomic number: 79, Atomic mass: 196.9655 g.mol -1, Electronegativity ccording to Pauling: 2.4, Densi
Group: 1. A substructure that imparts characteristic chemical behaviors to a molecule, for example, a carbo
Hafnium (Hf): Atomic number: 72, Atomic mass: 178.49 g.mol -1, Electronegativity: 1.3, Density: 13.07 g.cm-3 at 20
Halogen: An element of group VIIA (a. k. a. Group 18). The name means 'salt former'; halogens react with meta
Hassium (Hs): Atomic number: 108, Atomic mass: 264.8 g.mol -1, Electronegativity: unknown, Density: unknown, Melti
Helium (He): Atomic number: 2, Atomic mass: 4.00260 g.mol -1, Electronegativity: unknown, Density: 0.178*10 -3 g.
Holmium (Ho): Atomic number: 67, Atomic mass: 164.9 g.mol -1, Electronegativity: 1.2, Density: 8.8 g.cm-3 at 20°C
Hydrogen (H): Atomic number: 1, Atomic mass: 1.007825 g.mol -1, Electronegativity: 2.1, Density: 0.0899*10 -3 g.cm
Indium (In): Atomic number: 49, Atomic mass: 114.82 g.mol -1, Electronegativity: 2, Density: 7.31 g.cm-3 at 20°C
Iodine (I): Atomic number: 53, Atomic mass: 126.9045 g.mol -1, Electronegativity: 2.5, Density: 4.93 g.cm-3 at 2
Ionic Radius: The radii of anions and cations in crystalline ionic compounds, as determined by consistently partit
Ionization Energy: The energy needed to remove an electron from a gaseous atom or ion.
Ionization Energy (IE): The energy required to remove the outermost electron from an atom or a positive ion in its ground le
Iridium (Ir): Atomic number: 77, Atomic mass: 192.2 g.mol -1, Electronegativity: 2.2, Density: 22.4 g.cm-3 at 20°
Iron (Fe): Atomic number: 26, Atomic mass: 55.85 g.mol -1, Electronegativity: 1.8, Density: 7.8 g.cm-3 at 20°C
Isotope: Atoms of the same element with the same atomic number, but different number of neutrons. Isotope of
Krypton (Kr): Atomic number: 36, Atomic mass: 83.80 g.mol -1, Density: 3.73 10-3 g.cm-3 at 20°C, Melting point: -
Lanthanide: Elements 57-70 are called lanthanides. Electrons added during the Aufbau construction of lanthanide
Lanthanide Contraction: An effect that causes sixth period elements with filled 4f subshells to be smaller than otherwise ex
Lanthanum (La): Atomic number: 57, Atomic mass: 138.91 g.mol -1, Electronegativity: 1.1, Density: 6.18 g.cm-3 at 20
Lawrencium (Lr): Atomic number: 103, Atomic mass: (262) g.mol -1, Electronegativity: unknown, Density: unknown, Melti
Lead (Pb): Atomic number: 82, Atomic mass: 207.2 g.mol -1, Electronegativity: 1.8, Density: 11.34 g.cm-3 at 20
Lithium (Li): Atomic number: 3, Atomic mass: 6.941 g.mol -1, Electronegativity: 1.0, Density: 0.53 g.cm -3 at 20
Lutetium (Lu): Atomic number: 71, Atomic mass: 174.97 g.mol -1, Electronegativity: 1.2, Density: 9.7 g.cm-3 at 20°
Magnesium (Mg): Atomic number: 12, Atomic mass: 24.305 g.mol -1, Electronegativity: 1.2, Density: 1.74 g.cm -3 at 20
Manganese (Mn): Atomic number: 25, Atomic mass: 54.9380 g.mol -1, Electronegativity: 1.5, Density: 7.43 g.cm-3 at 20
Meitnerium (Mt): Atomic number: 109, Atomic mass: 265.9 g.mol -1, Electronegativity: unknown, Density: unknown, Melti
Mendelevium (Md): Atomic number: 101, Atomic mass: (258) g.mol -1, Electronegativity: unknown, Density: unknown, Melti
Mercury (Hg): Atomic number: 80, Atomic mass: 200.59 g.mol -1, Electronegativity: 1.9, Density: 13.6 g.cm-3 at 20
Metal: A metal is a substance that conducts heat and electricity, is shiny and reflects many colors of ligh
Molybdenum (Mo): Atomic number: 42, Atomic mass: 95.94 g.mol -1, Electronegativity: 1.8, Density: 10.2 g.cm-3 at 20°
Neodymium (Nd): Atomic number: 60, Atomic mass: 144.2 g mol -1, Electronegativity: 1.14, Density: 7.0 g cm-3, Meltin
Neon (Ne): Atomic number: 10, Atomic mass: 20.179 g.mol -1, Electronegativity: unknown, Density: 0.9*10 -3 g.cm
Neptunium (Np): Atomic number: 93, Atomic mass: (237) g.mol -1, Electronegativity: 1.3, Density: 20.25 g.cm-3 at 20
Nickel (Ni): Atomic number: 28, Atomic mass: 58.71 g.mol -1, Electronegativity: 1.8, Density: 8.9 g.cm-3 at 20°C
Niobium (Nb): Atomic number: 41, Atomic mass: 92.91 g.mol -1, Electronegativity: unknown, Density: 8.4 g.cm-3 at 2
Nitrogen (N): Atomic number: 7, Atomic mass: 14.0067 g.mol -1, Electronegativity: 3.0, Density: 1.25*10-3 g.cm-3 a
Nobelium (No): Atomic number: 102, Atomic mass: 259 g.mol -1, Electronegativity: unknown, Density: unknown, Melting
Nonmetal: A nonmetal is a substance that conducts heat and electricity poorly, is brittle or waxy or gaseous,
Osmium (Os): Atomic number: 76, Atomic mass: 190.2 g.mol -1, Electronegativity: 2.2, Density: 22.5 g.cm-3 at 20°
Oxygen (O): Atomic number: 8, Atomic mass: 15.999 g.mol -1, Electronegativity: 3.5, Density: 1.429 kg/m3 at 20°
Palladium (Pd): Atomic number: 46, Atomic mass: 106.42 g.mol -1, Electronegativity: 2.2, Density: 11.9 g.cm-3 at 20
Period: Rows in the periodic table are called periods. For example, all of the elements in the second row ar
Periodic Law: The periodic law states that physical and chemical properties of the elements recur in a regular way
Periodic Table: An arrangement of the elements according to increasing atomic number that shows relationships betwee
Periodic Trend: A regular variation in element properties with increasing atomic number that is ultimately due to re
Phosphorus (P): Atomic number: 15, Atomic mass: 30,9738 g.mol -1, Oxidation states: ± 3, 4, 5, Electronegativity: 2
Platinum (Pt): Atomic number: 78, Atomic mass: 195.09 g.mol -1, Electronegativity: 2.2, Density: 21.4 g.cm-3 at 20
Plutonium (Pu): Atomic number: 94, Atomic mass: (244) g.mol -1, Electronegativity: unknown, Density: 19.84 g.cm-3 at
Polonium (Po): Atomic number: 84, Atomic mass: (210) g.mol -1, Electronegativity: 2.0, Density: 9.51 g.cm-3 at 20°
Potassium (K): Atomic number: 19, Atomic mass: 39.0983 g.mol -1, Electronegativity: 0.8, Density: 0.86 g.cm -3 at 0
Praseodymium (Pr): Atomic number: 59 , Atomic mass: 140.91 g.mol -1, Electronegativity: 1.1, Density: 6.8 g.cm-3 at 20
Promethium (Pm): Atomic number: 61, Atomic mass: (147) g.mol -1, Electronegativity: unknown, Density: 6.475 g.cm-3 at
Protactinium (Pa): Atomic number: 91, Atomic mass: 231.0359 g.mol -1, Electronegativity: 1.5, Density: 15.37 g.cm-3 at
Radium (Ra): Atomic number: 88, Atomic mass: 226.0254 g.mol -1, Electronegativity: 0.9, Density: 5 g.cm-3 at 20°
Radon (Rn): Atomic number: 86, Atomic mass: (222) g.mol -1, Electronegativity: unknown, Density: 9.96*10-3g.cm3
Rhenium (Re): Atomic number: 75, Atomic mass: 186.23 g.mol -1, Electronegativity: 1.9, Density: 20.5 g.cm-3 at 20
Rhodium (Rh): Atomic number: 45, Atomic mass: 102.91 g.mol -1, Electronegativity: 2.2, Density: 12.4 g.cm-3 at 20
Rubidium (Rb): Atomic number: 37, Atomic mass: 85.4678 g.mol -1, Electronegativity: 0.8, Density: 1.53 g.cm-3 at 20
Ruthenium (Ru): Atomic number: 44, Atomic mass: 101.1 g.mol -1, Electronegativity: 2.2, Density: 12.2 g.cm-3 at 20°
Rutherfordium (Rf): Atomic number: 104, Atomic mass: 260.9 g.mol -1, Electronegativity: unknown, Density: unknown, Melti
Samarium (Sm): Atomic number: 62 Atomic mass: 150.35 g.mol -1 Electronegativity: 1.2 Density: 6.9 g.cm-3 at 20°C M
Scandium (Sc): Atomic number: 21, Atomic mass: 44.9559 g.mol -1, Electronegativity: unknown, Density: 3.0 g.cm-3 at
Seaborgium (Sg): Atomic number: 106, Atomic mass: 262.94 g.mol -1, Electronegativity: unknown, Density: unknown, Melt
Second Ionization Energy: The energy needed to remove an electron from an isolated +1 ion. The third ionization energy would b
Selenium (Se): Atomic number: 34, Atomic mass: 78.96 g.mol -1, Electronegativity: 2.4, Density: 4.79 g.cm-3 at 20°
Silicon (Si): Atomic number: 14, Atomic mass: 28.0855 g.mol -1, Electronegativity: 1.8, Density: 2.33 g.cm -3 at 2
Silver (Ag): Atomic number: 47, Atomic mass: 107.87 g.mol -1, Electronegativity: 1.9, Density: 10.5 g.cm-3 at 20
Sodium (Na): Atomic number: 11, Atomic mass: 22.98977 g.mol -1, Electronegativity: 0.9, Density: 0.97 g.cm -3 at
Strontium (Sr): Atomic number: 38, Atomic mass: 87.62 g.mol -1, Electronegativity: 1.0, Density: 2.6 g.cm-3 at 20°C
Sulfur (S): Atomic number: 16, Atomic mass: 32.06 g.mol -1, Electronegativity: 2.5, Density: 2.07 g.cm -3 at 20
Tantalum (Ta): Atomic number: 73, Atomic mass: 180.95 g.mol -1, Electronegativity: 1.5, Density: 16.69 g.cm-3 at 20
Technetium (Tc): Atomic number: 43, Atomic mass: (99) g.mol -1, Electronegativity: 1.9, Density: 11.5 g.cm-3 at 20°C
Tellurium (Te): Atomic number: 52, Atomic mass: 127.6 g.mol -1, Electronegativity: 2.1, Density: 6.24 g.cm-3, Meltin
Terbium (Tb): Atomic number: 65, Atomic mass: 158.92534 g.mol -1, Electronegativity: 1.2, Density: 8.3 g.cm-3 at 2
Thallium (Tl): Atomic number: 81, Atomic mass: 204.383 g.mol -1, Electronegativity: 1.8, Density: 11.71 g.cm-3 at 2
Thorium (Th): Atomic number: 90, Atomic mass: 232.04 g.mol -1, Electronegativity: 1.3, Density: 11.72 g.cm-3 at 20
Thulium (Tm): Atomic number: 69, Atomic mass: 168.93 g.mol -1, Electronegativity: 1.2, Density: 9.3 g.cm-3 at 20°
Tin (Sn): Atomic number: 50, Atomic mass: 118.69 g.mol -1, Electronegativity: 1.8, Density: 5.77g.cm-3 (alpha)
Titanium (Ti): Atomic number: 22, Atomic mass: 47.90 g.mol -1, Electronegativity: 1.5, Density: 4.51 g.cm-3 at 20°
Transition Metal: An element with an incomplete d subshell. Elements which have common cations with incomplete d subsh
Tungsten (W): Atomic number: 74, Atomic mass: 183.85 g.mol -1, Electronegativity accoridin to Pauling: 1.7, Densit
Ununbium (Uub): Atomic number: 112, Atomic mass: 276.8 g.mol -1, Electronegativity: unknown, Density: unknown, Melti
Ununhexium (Uuh): Atomic number: 116, Atomic mass: unknown, Electronegativity acoording to Pauling: unknown, Density:
Ununium (Uuu): Atomic number: 111, Atomic mass: 271.8 g.mol -1, Electronegativity acoording to Pauling: unknown, De
Ununoctium (Uuo): Atomic number: 118, Atomic mass: unknown, Electronegativity: unknown, Density: unknown, Melting poin
Ununpentium (Uup): Atomic number: 115, Atomic mass: unknown, Electronegativity acoording to Pauling: unknown, Density:
Ununquadium (Uuq): Atomic number: 114, Atomic mass: 289 g.mol -1, Electronegativity acoording to Pauling: unknown, Dens
Ununseptium (Uus): Atomic number: 117, Atomic mass: unknown, Electronegativity acoording to Pauling: unknown, Density:
Ununtrium (Uut): Atomic number: 113, Atomic mass: unknown, Electronegativity acoording to Pauling: unknown, Density:
Uranium (U): Atomic number: 92, Atomic mass: 238.03 g.mol -1, Electronegativity: 1.7, Density: 18.95 g.cm-3 at 20
Vanadium (V): Atomic number: 23, Atomic mass: 50.9414 g.mol -1, Electronegativity: 1.6, Density: 6.1 g.cm-3 at 20
Xenon (Xe): Atomic number: 54, Atomic mass: 131.29 g.mol -1, Electronegativity: unknown, Density: 5.9*10-3g.cm-3
Ytterbium (Yb): Atomic number: 70, Atomic mass: 173.04 g.mol -1, Electronegativity: 1.1, Density: 7 g.cm-3 at 20°C,
Yttrium (Y): Atomic number: 39, Atomic mass: 88.9059 g.mol -1, Electronegativity: 1.2, Density: 4.47 g.cm-3 at 20
Zinc (Zn): Atomic number: 30, Atomic mass: 65.37 g.mol -1, Electronegativity: 1.6, Density: 7.11 g.cm-3 at 20°
Zirconium (Zr): Atomic number: 40, Atomic mass: 91.22 g.mol -1, Electronegativity: 1.2, Density: 6.49 g.cm-3 at 20°

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