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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.
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 [7]). Many properties of promethium rely on its position among lanthanides and are intermediate between those of neodymium and samarium.
The reductions in atomic size due to the interjection of the d- and f-blocks are referred to as, respectively, the 'scandide' or 'd-block contraction', [n 3] and the 'lanthanide contraction'. [13] Relativistic effects also "increase the binding energy", and hence ionisation energy, of the electrons in "the 6s shell in gold and mercury, and the ...
The lanthanide contraction, i.e. the reduction in size of the Ln 3+ ion from La 3+ (103 pm) to Lu 3+ (86.1 pm), is often explained by the poor shielding of the 5s and 5p electrons by the 4f electrons. [18] Lanthanide oxides: clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium and gadolinium.
Lutetium is generally encountered in the 3+ oxidation state, having lost its two outermost 6s and the single 5d-electron. The lutetium atom is the smallest among the lanthanide atoms, due to the lanthanide contraction, [14] and as a result lutetium has the highest density, melting point, and hardness of the lanthanides. [15]
For example, the orbits are superior to the oris, and the pelvis is inferior to the abdomen. [1] Proximal and distal, which describe a position that is closer to (proximal) or farther from (distal) the trunk of the body. [1] For example, the shoulder is proximal to the arm, and the foot is distal to the knee.
This is a list of human anatomy mnemonics, categorized and alphabetized.For mnemonics in other medical specialties, see this list of medical mnemonics.Mnemonics serve as a systematic method for remembrance of functionally or systemically related items within regions of larger fields of study, such as those found in the study of specific areas of human anatomy, such as the bones in the hand ...
For example, the pronator teres muscle of the forearm. Unipennate muscles have fibres that run the entire length of only one side of a muscle, like a quill pen. For example, the fibularis muscles. Bipennate muscles consist of two rows of oblique muscle fibres, facing in opposite diagonal directions, converging on a central tendon.