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The Periodic Table

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping includes lithium (Li), sodium (Na), and potassium (K). All of these elements are shiny, conduct heat and electricity well, and have similar chemical properties. A second grouping includes calcium (Ca), strontium (Sr), and barium (Ba), which also are shiny, good conductors of heat and electricity, and have chemical properties in common. However,...

Periodic Classification of the Elements

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their electron configurations are added to the table, a periodic recurrence of similar electron configurations in the outer shells of these elements is observed. Because they are in the outer shells of an atom, valence electrons play the most important role in chemical reactions. The outer electrons have the highest energy of the electrons in an atom...

Effective Value of a Periodic Waveform

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The concept of effective value, the root mean square (RMS) value, is crucial in understanding electrical circuits and power delivery. This idea emerges from the necessity to measure the effectiveness of a voltage or current source in supplying power to a resistive load.
The effective value of a periodic current represents the direct current (DC) that conveys the same average power to a resistor as the periodic current itself. This concept is crucial when assessing AC circuits. To determine the...

The Periodic Table and Organismal Elements

The Periodic Table and Organismal Elements

The Periodic Table and Organismal Elements

The Periodic Table and Organismal Elements

Elements are the smallest units of matter that cannot be broken down further by chemical processes. There are 118 known elements, but not all of these are naturally occurring, and only a few of them are essential for life. Living matter is composed primarily of carbon, nitrogen, hydrogen, and oxygen, with smaller amounts of other elements like calcium, phosphorus, potassium, and sulfur. Other elements are also necessary for life but only in trace amounts.
Periodic Table Provides Information...

Properties of Transition Metals

Properties of Transition Metals

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.

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Related Experiment Video

Updated: Feb 14, 2026

Swimming Induced Paralysis to Assess Dopamine Signaling in Caenorhabditis elegans

Swimming Induced Paralysis to Assess Dopamine Signaling in Caenorhabditis elegans

Published on: April 3, 2019

Periodic paralysis.

Doreen Fialho¹, Robert C Griggs², Emma Matthews¹

¹MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, London, United Kingdom.

Handbook of Clinical Neurology

|February 27, 2018

Summary

This summary is machine-generated.

Periodic paralyses are muscle disorders caused by genetic defects in ion channels. Understanding these defects improves knowledge of triggers and leads to new treatments for muscle weakness.

Keywords:

Andersen–Tawil syndrome CACNA1S KCNJ2 SCN4A gating pore leak hyperkalemic periodic paralysis hypokalemic periodic paralysis muscle excitability paradoxic depolarization thyrotoxic periodic paralysis

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Area of Science:

Neuroscience
Genetics
Molecular Biology

Background:

Periodic paralyses are skeletal muscle channelopathies characterized by intermittent muscle weakness.
Attacks are often associated with abnormal serum potassium levels.
Genetic defects involve mutations in calcium, sodium, and potassium channel genes.

Purpose of the Study:

To elucidate the mechanisms by which genetic mutations in ion channels cause periodic paralyses.
To enhance understanding of the clinical manifestations and triggers of periodic paralysis attacks.
To explore novel therapeutic strategies based on improved pathophysiological insights.

Main Methods:

Genetic analysis to identify mutations in ion channel genes.
Electrophysiological studies to assess the impact of mutations on muscle excitability.
Clinical correlation to link genetic defects with patient symptoms and triggers.

Main Results:

Identified mutations in Ca_v1.1, Na_v1.4, K_ir2.1, K_ir3.4, and K_ir2.6 genes as causes of periodic paralyses.
Demonstrated how these mutations alter skeletal muscle excitability.
Linked specific channel defects to clinical phenomena and attack triggers.

Conclusions:

Genetic defects in skeletal muscle ion channels are the primary cause of periodic paralyses.
Understanding mutant channel function provides insights into disease mechanisms and triggers.
This knowledge is paving the way for the development of new therapeutic interventions.