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  2. 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)

  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. 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.

  5. Periodic trends - Wikipedia

    en.wikipedia.org/wiki/Periodic_trends

    The atomic number increases within the same period while moving from left to right, which in turn increases the effective nuclear charge. The increase in attractive forces reduces the atomic radius of elements. When we move down the group, the atomic radius increases due to the addition of a new shell. [5] [6] [7]

  6. Stellar evolution - Wikipedia

    en.wikipedia.org/wiki/Stellar_evolution

    These stars, known as neutron stars, are extremely small—on the order of radius 10 km, no bigger than the size of a large city—and are phenomenally dense. Their period of rotation shortens dramatically as the stars shrink (due to conservation of angular momentum ); observed rotational periods of neutron stars range from about 1.5 ...

  7. NGC 1333 - Wikipedia

    en.wikipedia.org/wiki/NGC_1333

    This nebula is in the western part [4] of the Perseus molecular cloud and is a young region of very active star formation, [6] being one of the best-studied objects of its type. [4] It contains a fairly typical hierarchy of star clusters that are still embedded in the molecular cloud in which they formed, [ 7 ] which are split into two main sub ...

  8. Stellar structure - Wikipedia

    en.wikipedia.org/wiki/Stellar_structure

    The internal structure of a main sequence star depends upon the mass of the star. In stars with masses of 0.3–1.5 solar masses (M ☉), including the Sun, hydrogen-to-helium fusion occurs primarily via proton–proton chains, which do not establish a steep temperature gradient. Thus, radiation dominates in the inner portion of solar mass stars.

  9. 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 ...