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  2. Lanthanide contraction - Wikipedia

    en.wikipedia.org/wiki/Lanthanide_contraction

    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.

  3. Lanthanide - Wikipedia

    en.wikipedia.org/wiki/Lanthanide

    The colors of the γ-sesquisulfides are La 2 S 3, white/yellow; Ce 2 S 3, dark red; Pr 2 S 3, green; Nd 2 S 3, light green; Gd 2 S 3, sand; Tb 2 S 3, light yellow and Dy 2 S 3, orange. [60] The shade of γ-Ce 2 S 3 can be varied by doping with Na or Ca with hues ranging from dark red to yellow, [ 49 ] [ 60 ] and Ce 2 S 3 based pigments are used ...

  4. Actinide contraction - Wikipedia

    en.wikipedia.org/wiki/Actinoid_contraction

    About 40-50% of the actinide contraction has been attributed to relativistic effects. [2] A decrease in atomic radii can be observed across the 5f elements from atomic number 89, actinium, to 102, nobelium. This results in smaller than otherwise expected atomic radii and ionic radii for the subsequent d-block elements starting with 103, lawrencium.

  5. Gastrointestinal physiology - Wikipedia

    en.wikipedia.org/wiki/Gastrointestinal_physiology

    These slow wave potentials must reach a threshold level for the action potential to occur, whereupon Ca 2+ channels on the smooth muscle open and an action potential occurs. As the contraction is graded based upon how much Ca 2+ enters the cell, the longer the duration of slow wave, the more action potentials occur. This, in turn, results in ...

  6. Lanthanide compounds - Wikipedia

    en.wikipedia.org/wiki/Lanthanide_compounds

    Lanthanide metals react exothermically with hydrogen to form LnH 2, dihydrides. [1] With the exception of Eu and Yb, which resemble the Ba and Ca hydrides (non-conducting, transparent salt-like compounds),they form black pyrophoric, conducting compounds [6] where the metal sub-lattice is face centred cubic and the H atoms occupy tetrahedral sites. [1]

  7. d-block contraction - Wikipedia

    en.wikipedia.org/wiki/D-block_contraction

    Other effects of the d-block contraction are that the Ga 3+ ion is smaller than expected, being closer in size to Al 3+.Care must be taken in interpreting the ionization potentials for indium and thallium, since other effects, e.g. the inert-pair effect, become increasingly important for the heavier members of the group.

  8. Inert-pair effect - Wikipedia

    en.wikipedia.org/wiki/Inert-pair_effect

    The inert-pair effect is the tendency of the two electrons in the outermost atomic s-orbital to remain unshared in compounds of post-transition metals.The term inert-pair effect is often used in relation to the increasing stability of oxidation states that are two less than the group valency for the heavier elements of groups 13, 14, 15 and 16.

  9. Lanthanum oxide - Wikipedia

    en.wikipedia.org/wiki/Lanthanum_oxide

    La 2 O 3 forms glasses of high density, refractive index, and hardness. Together with oxides of tungsten, tantalum, and thorium, La 2 O 3 improves the resistance of the glass to attack by alkali. La 2 O 3 is an ingredient in some piezoelectric and thermoelectric materials. La 2 O 3 has been examined for the oxidative coupling of methane. [10]