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  2. Promethium - Wikipedia

    en.wikipedia.org/wiki/Promethium

    The element's atomic radius is the second largest among all the lanthanides but is only slightly greater than those of the neighboring elements. [5] It is the most notable exception to the general trend of the contraction of lanthanide atoms with the increase of their atomic numbers (lanthanide contraction [6]). Many properties of promethium ...

  3. Period 3 element - Wikipedia

    en.wikipedia.org/wiki/Period_3_element

    A period 3 element is one of the chemical elements in the third row (or period) of the periodic table of the chemical elements.The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into ...

  4. Atomic radii of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Atomic_radii_of_the...

    The Bohr radius is consequently known as the "atomic unit of length". It is often denoted by a 0 and is approximately 53 pm. Hence, the values of atomic radii given here in picometers can be converted to atomic units by dividing by 53, to the level of accuracy of the data given in this table. Atomic radii up to zinc (30)

  5. Period (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Period_(periodic_table)

    A period on the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, elements in the same group (column) have similar chemical and physical properties, reflecting the periodic law.

  6. Atomic radius - Wikipedia

    en.wikipedia.org/wiki/Atomic_radius

    The atomic radius of a chemical element is a measure of the size of its atom, usually the mean or typical distance from the center of the nucleus to the outermost isolated electron. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius.

  7. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    a Group 1 is composed of hydrogen (H) and the alkali metals. Elements of the group have one s-electron in the outer electron shell. Hydrogen is not considered to be an alkali metal as it is not a metal, though it is more analogous to them than any other group. This makes the group somewhat exceptional.

  8. Unbinilium - Wikipedia

    en.wikipedia.org/wiki/Unbinilium

    Unbinilium, also known as eka-radium or element 120, is a hypothetical chemical element; it has symbol Ubn and atomic number 120. Unbinilium and Ubn are the temporary systematic IUPAC name and symbol , which are used until the element is discovered, confirmed, and a permanent name is decided upon.

  9. Fermium - Wikipedia

    en.wikipedia.org/wiki/Fermium

    Fermium is a synthetic chemical element; it has symbol Fm and atomic number 100. It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not been prepared yet. [ 5 ]