Name: atomic charges, bonds, and compounds
Uploaded: 2023-06-23T15:38:43.000Z
Duration: 1 min 23 s
Channel: JoVE

Les ions sont des atomes chargés électriquement qui ont gagné ou perdu des électrons. Un atome qui perd des électrons et devient chargé positivement est un cation, tandis qu’un atome qui gagne des électrons et devient chargé négativement est un anion.
Les ions sont essentiels à de nombreux processus physiologiques, tels que la transmission de l’influx nerveux et la contraction musculaire.
Les molécules sont des combinaisons de deux atomes ou plus qui partagent des électrons. Ils peuvent être constitués d’atomes d’un élément, comme une molécule d’oxygène, ou d’atomes d’éléments différents, comme une molécule d’eau.
Un composé est une combinaison d’atomes de différents éléments liés chimiquement dans une proportion fixe, que les électrons soient transférés ou partagés.
Les composés ioniques sont formés par interaction électrostatique entre des ions métalliques et non métalliques, comme dans le sel de table ordinaire, avec un cation sodium et un anion chlorure liés ensemble par des interactions électrostatiques.
Les composés moléculaires se forment lorsque des atomes non métalliques sont liés par des liaisons covalentes. Par exemple, le méthane est un composé moléculaire où quatre atomes d’hydrogène partagent des électrons avec un atome de carbone dans une proportion spécifique.

ions, molécules et composés

Les ions - Lorsqu'un atome participe à une réaction chimique qui entraîne la donation ou l'acceptation d'un ou plusieurs électrons, l'atome devient chargé positivement ou négativement. Cela se produit fréquemment pour que la plupart des atomes aient une couche de valence complète. Cela peut se produire soit en gagnant des électrons pour remplir une couche qui est plus qu'à moitié pleine, soit en donnant des électrons pour vider une couche qui est moins qu'à moitié pleine, laissant ainsi la couche électronique plus petite suivante comme la nouvelle couche de valence complète. Un atome avec une charge électrique - positive ou négative - est un ion. Par exemple, le potassium (K) est un élément important dans toutes les cellules du corps. Son numéro atomique est 19. Il a un seul électron dans sa couche de valence. Cette caractéristique rend le potassium très susceptible de participer à des réactions chimiques dans lesquelles il donne un électron. La perte va entraîner la charge positive des protons du potassium à être plus influente que la charge négative des électrons du potassium. En d'autres termes, l'ion potassium résultant sera légèrement positif. Un ion chargé positivement est appelé un cation. Un autre élément, le fluor (F), un composant des os et des dents, a un numéro atomique de neuf. Il a sept électrons dans sa couche de valence. Le fluor est très susceptible de se lier à d'autres atomes de manière à accepter un électron. Lorsqu'il le fait, ses électrons dépasseront ses protons d'un et il aura une charge globale négative. Un ion chargé négativement est appelé un anion. Les ions sont essentiels au bon fonctionnement du corps, donc leurs déséquilibres peuvent entraîner des problèmes de santé. Par exemple, un déséquilibre de l'ion sodium peut provoquer des maladies cardiovasculaires. Des niveaux de calcium sanguin bas peuvent provoquer une tétanie - contractions musculaires involontaires incontrôlables. Les molécules - Les molécules sont tout simplement deux atomes ou plus liés chimiquement. Les molécules peuvent être composées d'atomes du même élément, comme une molécule de gaz d'oxygène, formée par liaison entre deux atomes d'oxygène respectivement, ou les molécules peuvent être formées par liaison entre des atomes d'éléments différents, comme une molécule de gaz de dioxyde de carbone, formée entre des atomes d'oxygène et de carbone. Les composés - Un composé est une substance pure formée par liaison de deux atomes ou plus dans une proportion fixe. Par exemple, le glucose est un combustible corporel important. Il est toujours composé des mêmes trois éléments : le carbone, l'hydrogène et l'oxygène, dans les mêmes quantités relatives. Dans le glucose, il y a toujours six unités de carbone et six unités d'oxygène pour chaque douze unités d'hydrogène. Ce texte est partiellement adapté de <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/2-2-chemical-bonds?query=when%20a%20atom%20participates&target=%7B%22type%22%3A%22search%22%2C%22index%22%3A0%7D#fs-id2113058">Openstax, Anatomy and Physiology 2e, Section 2.2 Chemical Bonds</a> and Openstax, <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/2-1-elements-and-atoms-the-building-blocks-of-matter?query=For%20example%2C%20the%20compound%20glucose%20is%20an%20important%20body%20fuel.%20It%20is%20always%20composed%20of%20the%20same%20three%20elements&target=%7B%22type%22%3A%22search%22%2C%22index%22%3A0%7D#fs-id1882474">Anatomy and Physiology 2e, Section 2.1 Elements and Atoms: The Building Blocks of Matter</a>.

Ions, Molécules et Composés

Ions - Lorsqu’un atome participe à une réaction chimique qui entraîne le don ou l’acceptation d’un ou plusieurs électrons, l’atome devient positivement ...

Education

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JoVE Core

Anatomy and Physiology

Anatomie et physiologie

Unit 1

Unité 1

Fundamentals of Chemistry

Les fondamentaux de la chimie

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

Ions, Molecules, and Compounds

atomic charges, bonds, and compounds

Atoms can gain or lose electrons during chemical reactions and become ions. An ion is an atom with an electrical charge. This charge is positive or negative, and it often helps the atom reach a full valence shell.

Some atoms are more likely to donate electrons, while others are more likely to accept them. Potassium is one example. It has atomic number 19 and one electron in its valence shell, so it is likely to donate that electron and become a slightly positive ion called a cation. Fluorine is another example. It has atomic number 9 and seven electrons in its valence shell, so it is likely to accept one electron and become a negatively charged ion called an anion.

Ions are important for normal body function, so an imbalance can cause health problems. A sodium ion imbalance can contribute to cardiovascular diseases. Low blood calcium levels can also cause tetany, which is marked by uncontrollable involuntary muscle contractions.

Molecules and compounds are related but not the same. A molecule is two or more atoms chemically bonded together. The atoms may be the same element, as in oxygen gas, or different elements, as in carbon dioxide gas. A compound is a pure substance made when two or more atoms bond in a fixed proportion.

Glucose is a useful example of a compound. It is an important body fuel and always contains the same elements in the same relative amounts: carbon, hydrogen, and oxygen. In glucose, there are always six carbon units and six oxygen units for every twelve hydrogen units.

Atomic Charges, Bonds, and Compounds

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electron behavior

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introduction to chemical bonds

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colloids and suspensions

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key terms and concepts

Learn how atoms become ions, why cations and anions form, and how molecules and compounds differ using potassium, fluorine, oxygen, carbon dioxide, and glucose.

Atomic Charges, Bonds, and Compounds | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

Atomic Charges, Bonds, and Compounds

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