chemistry

Ionic Radius Periodic Table of the Elements Home > Fundamental Physical Constants - Chemical - Physical - Thermochemical Data > Ionic Radius Periodic Table of the Elements Periodic Table with Ionic Radius   Ion size plays an important role in determining the structure and stability of ionic solids, the properties of ions in aqueous solution, and the biological effects of ions. As with atoms, it is impossible to define precisely the sizes of ions . Ionic radii are determined from the measured distances between ion centers in ionic compounds. A table of ionic radii is given below.   Table 1: Periodic Table with Ionic Radii (Å) of the elements 1 2 3 4 5 6 7 H 1.46             Li 0

Ionization Energies Periodic Table of the Elements Home > Fundamental Physical Constants - Chemical - Physical - Thermochemical Data > Electronegativities Periodic Table of the Elements > Electron Affinity Periodic Table of the Elements > Ionization Energy Periodic Table of the Elements Periodic Table with Ionization Energies   The ionization energy of an atom or ion is the minimum energy required to remove an electron from the ground state of the isolated gaseous atom or ion. The first ionization energy , I 1 , is the energy needed to remove the first electron from a neutral atom. M (g) —› M + (g) + e - It is related to the atom's electronegativity and electron affinity . Tables of electronegativities and electron affinities were given in the posts entitled " Electronegativities Periodic Table of the Elements " and " Electron Affinities Periodic Table of the Elements ". A table of first

Electron affinities Periodic Table of the Elements Home > Fundamental Physical Constants - Chemical - Physical - Thermochemical Data > Electronegativities Periodic Table of the Elements > Electron Affinities Periodic Table of the Elements Periodic Table with Electron Affinities   The electron affinity of an atom is the energy released when an electron is added to it. It is related to the atom's ionization energy and electronegativity . The basic difference between ionization energy and electron affinity is that ionization energy measures the ease with which an atom loses an electron, while electron affinity measures the ease with which an atom gains an electron.   Table 1: Periodic Table with Electron Affinities (kJ/mol) of gaseous atoms of the elements 1 2 3 4 5 6 7 8 9 10

Standard Enthalpies of Formation of selected organic compounds Home > Fundamental Physical Constants - Chemical - Physical - Thermochemical Data > Standard Enthalpies of Formation of Inorganic Compounds > Standard Enthalpies of Formation of Organic Compounds Standard Enthalpies of Formation of Organic Compounds   The standard enthalpy of formation ΔΗ° f of a substance is the change in enthalpy for the reaction that forms 1 mol of the substance from its elements with all reactants and products at 1 atm pressure and usually 298.15 K. For any element in its most stable state at 298 K and 1 atm pressure, ΔΗ° f = 0. Standard enthalpies of formation of inorganic compounds were given in a previous post.   Table 1: Standard Molar Enthalpies of Formation ΔΗ° f at 25 °C (298.15K) Substance Formula ΔΗ° f   Acetylene C 2 H 2 (g) 226.7

Electronegativities Periodic Table of the Elements Home > Fundamental Physical Constants - Chemical - Physical - Thermochemical Data > Periodic Table with Electronegativities Periodic Table with Electronegativities   Electronegativity is defined as the ability of an atom in a molecule to attract electrons to itself. The electronegativity of an atom in a molecule is related to the atom's ionization energy and electron affinity , which are properties of isolated atoms. An atom with a high ionization energy and with a very negative electron affinity both resists having its electrons attracted away and attracts electrons from other atoms. It is highly electronegative. Linus Pauling developed the first and most widely used electronegativity scale which is based on thermochemical data (Table 1). There is generally an increase in electronegativity from left to right across a row of the periodic table. Electonegativity decr

Standard Enthalpies of Formation of selected Inorganic Compounds Home > Fundamental Physical Constants - Chemical - Physical - Thermochemical Data > Bond Dissociation Enthalpies > Standard Enthalpies of Formation of Inorganic Compounds Standard Enthalpies of Formation of Inorganic Compounds   The standard enthalpy of formation ΔΗ° f of a substance is the change in enthalpy for the reaction that forms 1 mol of the substance from its elements with all reactants and products at 1 atm pressure and usually 298.15 K. For any element in its most stable state at 298 K and 1 atm pressure, ΔΗ° f = 0. A bond dissociation enthalpies table can be found in the post "Bond Dissociation Enthalpies " .   Table 1: Standard Molar Enthalpies of Formation ΔΗ° f at 25 °C (298.15K) Substance Formula ΔΗ° f   Calcium carbonate CaCO 3 (s) -1207.1