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The lanthanide contraction is the greater-than-expected decrease in atomic radii and ionic radii of the elements in the lanthanide series, from left to right. It is caused by the poor shielding effect of nuclear charge by the 4f electrons along with the expected periodic trend of increasing electronegativity and nuclear charge on moving from left to right.
The lanthanide (/ ˈ l æ n θ ə n aɪ d /) or lanthanoid (/ ˈ l æ n θ ə n ɔɪ d /) series of chemical elements [a] comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals.
The d-block contraction is less pronounced than the lanthanide contraction but arises from a similar cause. In this case, it is the poor shielding capacity of the 3d-electrons which affects the atomic radii and chemistries of the elements immediately following the first row of the transition metals, from gallium (Z = 31) to bromine (Z = 35). [19]
The d-block contraction (sometimes called scandide contraction [1]) is a term used in chemistry to describe the effect of having full d orbitals on the period 4 elements. The elements in question are gallium , germanium , arsenic , selenium , bromine , and krypton [ citation needed ] .
The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), [1] are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals.
The Trump administration has ended extended protections granted to thousands of Venezuelans in the United States and is in talks to repatriate them, U.S. Homeland Security Secretary Kristi Noem ...
Due to the effects of the lanthanide contraction, yttrium and lutetium are very similar in properties. Yttrium and lutetium have essentially the chemistry of the heavy lanthanides, but scandium shows several differences due to its small size. This is a similar pattern to those of the early transition metal groups, where the lightest element is ...
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