In the case of the more complex metals (i.e., the transition elements), conductivities are better explained by the band theory, which takes into account not only the presence of free electrons but also their interaction with so-called d electrons. According to this concept, the individual atoms in such metals have lost their valence electrons to the entire solid, and these free electrons that give rise to conductivity move as a group throughout the solid. The high electrical and thermal conductivities of the simple metals (i.e., the non-transition metals of the periodic table) are best explained by reference to the free-electron theory. The most reactive include lithium, potassium, and radium, whereas those of low reactivity are gold, silver, palladium, and platinum. Metals differ widely in their chemical reactivity. They do, however, combine more readily with nonmetals (e.g., oxygen and sulfur), which generally have more than half the maximum number of valence electrons. Because of this characteristic, metals tend not to form compounds with each other. Typically, the atoms of metals contain less than half the full complement of electrons in their outermost shell. In most cases, they have a relatively simple crystal structure distinguished by a close packing of atoms and a high degree of symmetry. Liquid metal See all videos for this article These data can then be re-analysed centrally and combined, if. ![]() Rather than extracting summary (aggregate) data from study publications or from investigators, the original research data are sought directly from the researchers responsible for each study. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space! IPD meta-analysis is a specific type of systematic review.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.From tech to household and wellness products. Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions. ![]() Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.
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