Name: how atoms bond to reach stability
Uploaded: 2023-06-23T15:38:43.000Z
Duration: 1 min 1 s
Channel: JoVE

Wiązania chemiczne utrzymują razem atomy cząsteczki lub związku. Wiązania powstają, gdy elektrony w powłoce walencyjnej atomu są oddawane lub dzielone z innymi atomami.
Na przykład wiązania jonowe powstają, gdy atomy oddają lub przyjmują elektrony, wypełniając swoją powłokę walencyjną. Atom, który oddaje elektrony i staje się naładowany dodatnio, jest kationem, podczas gdy ten, który przyjmuje elektrony i staje się naładowany ujemnie, jest anionem.
W soli kuchennej związek między kationem sodu a anionem chlorkowym jest wiązaniem jonowym.
Wiązania kowalencyjne powstają między atomami, które wzajemnie dzielą jedną lub więcej par elektronów walencyjnych.
Na przykład dwa atomy wodoru mogą dzielić parę elektronów, tworząc pojedyncze wiązanie kowalencyjne. Tlen i azot mogą dzielić dwie i trzy pary elektronów, tworząc wiązania podwójne i potrójne.

wprowadzenie do wiązań chemicznych

Introduction to Chemical Bonds

Chemiczne wiązania decydują o stabilności energetycznej atomu i jego tendencji do tworzenia chemicznych wiązań z innymi atomami. Elektrony ostatniej warstwy energetycznej odgrywają kluczową rolę w tych procesach. Wewnętrzna powłoka elektronowa ma maksymalną pojemność dwóch elektronów, natomiast kolejne dwie powłoki elektronowe mogą pomieścić maksymalnie osiem elektronów. To jest znane jako reguła oktetu, która głosi, że, z wyjątkiem najbardziej wewnętrznej powłoki, atomy są energetycznie najbardziej stabilne, gdy mają osiem elektronów w powłoce walencyjnej, czyli najbardziej zewnętrznej powłoce elektronowej.

Niemniej jednak nie wszystkie pierwiastki posiadają wystarczającą ilość elektronów, aby wypełnić swoje najbardziej zewnętrzne powłoki. Dlatego atomy tworzą chemiczne wiązania z innymi atomami, zdobywając w ten sposób potrzebne elektrony, aby uzyskać stabilną konfigurację elektronową. Więc wiązanie chemiczne to siła, która trzyma atomy razem w molekule lub związku chemicznym.

Chemiczne wiązania jonowe

Atomy mogą zyskać lub stracić elektrony, aby wypełnić swoje powłoki walencyjne, co prowadzi do powstania naładowanych elektrycznie jonów. Kationy to dodatnio naładowane atomy, które tracą elektrony, podczas gdy aniony to atomy, które zyskują elektrony, stając się negatywnie naładowane. Różnice w ładunkach kationów i anionów powodują umiarkowanie silne przyciąganie wzajemne, utrzymujące atomy w bliskim sąsiedztwie, co skutkuje utworzeniem trwałego wiązania jonowego. Przykładem takiego wiązania jest zwykła sól kuchenna, która zawdzięcza swoje istnienie właśnie wiązaniom jonowym.

Chemiczne wiązania kowalencyjne

Innym sposobem zaspokojenia zasady oktetu jest dzielenie elektronów między atomami w celu utworzenia wiązań kowalencyjnych. Wiązania te są silniejsze i znacznie bardziej powszechne niż wiązania jonowe w cząsteczkach organizmów żywych. Wiązania kowalencyjne występują w organicznych cząsteczkach węglowych, takich jak nasza DNA i białka. Są także powszechne w cząsteczkach nieorganicznych, takich jak woda, dwutlenek węgla i tlen.

Wiązania wodorowe

Wiązanie wodorowe powstaje, gdy słabo dodatnio naładowany atom wodoru, już związany z jednym atomem elektroujemnym (np. tlenem w cząsteczce wody), przyciągany jest do innego atomu elektroujemnego z innej cząsteczki. Najczęstszym przykładem wiązania wodorowego w świecie naturalnym jest to, które występuje między cząsteczkami wody. Zjawisko to ma miejsce, gdy dwie krople deszczu łączą się w większą kroplę lub strumień wlewa się do rzeki. Wiązanie wodorowe występuje, ponieważ słabo ujemnie naładowany atom tlenu jednej cząsteczki wody przyciąga słabo dodatnie atomy wodoru dwóch innych cząsteczek wody.

Ten tekst jest adaptacją z <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/2-2-chemical-bonds?query=chemical%20bond&target=%7B%22type%22%3A%22search%22%2C%22index%22%3A0%7D#fs-id1493624">Openstax, Anatomy and Physiology 2e, Section 2.2: Chemical Bonds.</a> <a href="https://openstax.org/books/biology-ap-courses/pages/2-1-atoms-isotopes-ions-and-molecules-the-building-blocks?query=chemical%20bonds">Openstax, </a><a href="https://openstax.org/books/biology-ap-courses/pages/2-1-atoms-isotopes-ions-and-molecules-the-building-blocks?query=chemical%20bonds">Biology for AP® Courses</a><a href="https://openstax.org/books/biology-ap-courses/pages/2-1-atoms-isotopes-ions-and-molecules-the-building-blocks?query=chemical%20bonds"> Section </a><a href="https://openstax.org/books/biology-ap-courses/pages/2-1-atoms-isotopes-ions-and-molecules-the-building-blocks?query=chemical%20bonds">2.1 Atoms, Isotopes, Ions, and Molecules: The Building Blocks.</a>

Wprowadzenie do wiązań chemicznych

Wiązania chemiczne
Elektrony najbardziej zewnętrznego poziomu energetycznego decydują o stabilności energetycznej atomu i jego tendencji do tworzenia wiązań chemicznych z ...

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how atoms bond to reach stability

Atoms bond to become more stable, and their outermost electrons play the biggest role in that process. The inner electron shell can hold two electrons. The next two shells can each hold eight electrons. This is called the octet rule. It states that, except for the innermost shell, atoms are most stable when their valence shell, or outer shell, has eight electrons.

When atoms do not have enough electrons to fill that outer shell, they form chemical bonds with other atoms. A chemical bond is the force that holds atoms together in a molecule or compound. These bonds let atoms reach a more stable electron arrangement.

One common type is an ionic bond. In this case, atoms gain or lose electrons to fill their valence shell. When they do this, they become ions. A cation is a positively charged ion that has lost electrons. An anion is a negatively charged ion that has gained electrons. The opposite charges attract each other and keep the ions close together. This close association forms an ionic bond. Table salt is a common example of a substance made through ionic bonding.

Another way atoms satisfy the octet rule is by sharing electrons. This creates covalent bonds. Covalent bonds are stronger and much more common than ionic bonds in the molecules of living organisms. They are found in carbon-based organic molecules such as DNA and proteins. They also occur in inorganic molecules like water, carbon dioxide, and oxygen.

Hydrogen bonds are a weaker kind of attraction. They form when a weakly positive hydrogen atom, already bonded to another electronegative atom such as oxygen, is attracted to a different electronegative atom in another molecule. Water is the most common example. Hydrogen bonding helps explain why raindrops can merge into larger beads and why a creek can flow into a river.

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How Atoms Bond to Reach Stability

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