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Voltage-gated ion channels are often specific to ions, including Na +, K +, Ca 2+, and Cl −. Each of these ions plays an important role in the electrical behavior of the cell. [9] The gates also have unique properties with important physiological implications. For example, Na + channels open and close rapidly, while K + gates open and close ...
This website is also cited in the CRC Handbook as source of Section 1, subsection Electron Configuration of Neutral Atoms in the Ground State. 91 Pa : [Rn] 5f 2 (3 H 4) 6d 7s 2; 92 U : [Rn] 5f 3 (4 I o 9/2) 6d 7s 2; 93 Np : [Rn] 5f 4 (5 I 4) 6d 7s 2; 103 Lr : [Rn] 5f 14 7s 2 7p 1 question-marked; 104 Rf : [Rn] 5f 14 6d 2 7s 2 question-marked
[65] [82]: 126–127 While it was previously thought that the heavier alkali metals also formed octahedral hexaaqua ions, it has since been found that potassium and rubidium probably form the [K(H 2 O) 8] + and [Rb(H 2 O) 8] + ions, which have the square antiprismatic structure, and that caesium forms the 12-coordinate [Cs(H 2 O) 12] + ion.
The configuration that corresponds to the lowest electronic energy is called the ground state. Any other configuration is an excited state. As an example, the ground state configuration of the sodium atom is 1s 2 2s 2 2p 6 3s 1, as deduced from the Aufbau principle (see below).
For example, 15-crown-5 has a high affinity for sodium because the cavity size of 15-crown-5 is 1.7–2.2 Å, which is enough to fit the sodium ion (1.9 Å). [ 19 ] [ 20 ] Cryptands, like crown ethers and other ionophores , also have a high affinity for the sodium ion; derivatives of the alkalide Na − are obtainable [ 21 ] by the addition of ...
The difference in extracellular and intracellular ion concentration, maintained by the sodium-potassium pump, produce electrical signals in the form of action potentials that supports cardiac muscle contraction and promote long distance communication between neurons. [10] Sodium is the most prevalent metallic ion in extracellular fluid. [105]
The energy required to transfer an electron from a sodium atom to a chlorine atom (the difference of the 1st ionization energy of sodium and the electron affinity of chlorine) is small: +495.8 − 349 = +147 kJ mol −1. This energy is easily offset by the lattice energy of sodium chloride: −783 kJ mol −1. [3]
Due to the electrostatic and chemical properties, K + ions are larger than Na + ions, and ion channels and pumps in cell membranes can differentiate between the two ions, actively pumping or passively passing one of the two ions while blocking the other. [90] hormone secretion and action; vascular tone; systemic blood pressure control