Name: chemical bonds: types and strength
Uploaded: 2023-04-30T18:28:31.000Z
Duration: 2 min 40 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-1

Chemical Bonds

Когда атомы сближаются, их ядра отталкиваются друг от друга, как и электроны. В то же время электроны от каждого атома притягиваются к ядрам друг друга и располагаются таким образом, чтобы максимизировать силы притяжения между атомами при минимизации сил отталкивания.
Если это приводит к возникновению чистой силы притяжения, потенциальная энергия системы снижается. Это взаимодействие называется химической связью.
Однако не каждая комбинация атомов может образовывать устойчивые химические связи. Химическое поведение атома в первую очередь определяется тем, какие формы связей и к какому типу они относятся. Понимание связей между атомами, из которых состоит соединение, помогает понять и предсказать их молекулярное поведение.
Энергия связи — это энергия, необходимая для разрыва связи в одном моле газообразного соединения. Это зависит от типа связанных атомов и количества задействованных электронов. Прочность связи увеличивается с увеличением энергии связи.
Тип связанных атомов и количество задействованных электронов также влияют на длину связи, которая представляет собой среднее расстояние между ядрами двух связанных атомов и обратно пропорционально кратности связи и прочности связи.
Наиболее распространенные взаимодействия связей находятся в спектре, варьирующемся от ионных связей, которые включают электростатическое притяжение между противоположно заряженными ионами, до ковалентных связей, которые делят валентные электроны между атомами.
Ионные связи являются основным взаимодействием, обнаруженным в ионных соединениях. Составляющие катионы и анионы удерживаются вместе электростатическими силами притяжения. Часто образованию ионов предшествует перенос валентных электронов между участвующими в нем атомами.
Атом, который теряет электроны, становится катионом, в то время как атом, принимающий электроны, становится анионом. Перенос электронов обычно дает каждому иону ближайшую конфигурацию инертного газа, которая достигается при наименьшем изменении числа электронов, что делает ионы энергетически более стабильными.
При ковалентной связи общие электроны взаимодействуют с ядрами связывающих атомов и снижают потенциальную энергию. Двойные и тройные связи делят две и три пары электронов между атомами соответственно. Поскольку это увеличивает число электронов, подверженных дополнительным силам притяжения от другого ядра, прочность связи увеличивается с кратностью связи.

Химические связи

Атомы участвуют в образовании химической связи чтобы приобрести завершенную электронную конфигурацию валентной оболочки, аналогичную конфигурации ближайшего к нему по атомному номеру благородного газа. Ионные, ковалентные и металлические связи являются одними из важных типов химических связей. Энергия и длина связи определяют прочность химической связи.

Типы химических связей

Ионная связь образуется за счет электростатического притяжения между катионами и анионами. Зачастую ионы образуются в результате переноса электронов от одного участвующего атома к другому. Однако эти связи не имеют определенной направленности, поскольку электростатическая сила притяжения распределена равномерно по трехмерному пространству.

Ковалентная связь — это химическая связь, образованная за счет совместного использования электронных пар между соседними атомами. Общая пара электронов называется связывающей парой. Ковалентные связи имеют направленный характер.

Между двумя атомами металла образуется металлическая связь. Металлическая связь описывается «моделью электронного моря». Модель, основанная на низкой энергии ионизации металлов, утверждает, что атомы металлов легко теряют свои валентные электроны и становятся катионами. Эти валентные электроны создают пул делокализованных электронов, окружающих катионы по всему металлу.

Энергия связи и длина связи

Прочность ковалентной связи измеряется энергией, необходимой для ее разрыва, то есть энергией, необходимой для разделения связанных атомов. Для разделения любой пары связанных атомов требуется энергия. Чем прочнее связь, тем больше энергии требуется для ее разрыва.

Энергия, необходимая для разрыва определенной ковалентной связи в одном моле газообразных молекул, называется энергией связи или энергией диссоциации связи. Энергия связи двухатомной молекулы определяется как стандартное изменение энтальпии эндотермической реакции. Молекулы с тремя и более атомами имеют две и более связи. Сумма всех энергий связей в такой молекуле равна стандартному изменению энтальпии эндотермической реакции, разрывающей все связи в молекуле.

Прочность связи между двумя атомами увеличивается с увеличением числа электронных пар в связи. Как правило, чем больше количество связей между двумя атомами, тем короче длина связи и тем выше ее прочность. Таким образом, тройные связи прочнее и короче двойных связей между теми же двумя атомами; точно так же двойные связи прочнее и короче, чем одинарные связи между теми же двумя атомами. Когда один атом связывается с различными атомами в группе, сила связи обычно уменьшается по мере продвижения вниз по группе.

Этот текст адаптирован из Openstax, Химия 2e, Раздел 7.1: Ионная связь, Openstax, Раздел 7.2: Ковалентная связь, Раздел 10.5: Твердое состояние вещества и Раздел 7.5. Прочность связи: ковалентные связи.


Атомы участвуют в образовании химических связей, чтобы получить полную электронную конфигурацию валентной оболочки, аналогичную конфигурации ближайшего к ...

Education

JoVE Core

Organic Chemistry

Органическая химия

Unit 1

Раздел 1

Covalent Bonding and Structure

Ковалентная связь и структура

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

chemical bonds: types and strength

Chemical bonds help atoms reach a full valence shell like the nearest noble gas. The main bond types are ionic, covalent, and metallic. Bond energy and bond length also help explain how strong a bond is.

An ionic bond forms from electrostatic attraction between cations and anions. In many cases, one atom transfers electrons to another atom, and the ions form from that transfer. Ionic bonds have no defined direction because the attraction spreads evenly through three-dimensional space.

A covalent bond forms when adjacent atoms share electron pairs. The shared pair is called the bonding pair. Covalent bonds are directional, so the atoms are linked in a specific orientation.

A metallic bond forms between two metal atoms. The electron sea model describes this type of bonding. In this model, metal atoms lose valence electrons easily and become cations, while the delocalized electrons form a pool around the cations across the metal.

The strength of a covalent bond is measured by the energy needed to break it and separate the bonded atoms. Stronger bonds require more energy. For one mole of gaseous molecules, this value is called bond energy, or bond dissociation energy. For a diatomic molecule, it is the standard enthalpy change for the endothermic reaction that breaks the bond.

Molecules with three or more atoms have more than one bond. In those cases, the total bond energy is the sum of all bond energies needed to break every bond in the molecule. Bond strength also increases as the number of electron pairs in the bond increases. Triple bonds are stronger and shorter than double bonds between the same atoms, and double bonds are stronger and shorter than single bonds. When one atom bonds to different atoms in a group, bond strength usually decreases as you move down the group.

Chemical Bonds: Types and Strength

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Carbon Compounds in Everyday Life

Organic chemistry focuses on carbon compounds called organic compounds. These compounds may come from living things or be made by chemists. Carbon is the main element in them, and it bonds with other carbon atoms as well as hydrogen, oxygen, nitrogen, and sulfur. Carbon can form up to four strong bonds. That ability lets carbon atoms build chains and rings of many sizes, shapes, and levels of complexity. Not every carbon-containing substance is classified as organic. Carbonates, cyanides, and...

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Atomic Orbitals and Quantum Numbers

Atomic orbitals and quantum numbers describe how electrons are arranged around the nucleus. An atom has a small, positively charged nucleus with electrons surrounding it. The nucleus contains protons and neutrons, and the quantum mechanical model gives a better picture of this structure than older models. Protons carry a +1 charge and have a mass of 1.0073 amu. Neutrons have no charge and have a mass of 1.0087 amu. Electrons carry a −1 charge and have a mass of 0.00055 amu. The number of...

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Electron filling in atoms follows a set order based on orbital energy. The Aufbau principle says each new electron enters the lowest-energy subshell available. The Pauli exclusion principle says no two electrons can share the same set of four quantum numbers. Hund’s rule of maximum multiplicity says electrons stay unpaired in equal-energy orbitals when possible. The order of filling follows the relative energies of the subshells. A common sequence is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, and so on.

chemical bonds

Chemical bonds help atoms reach a full valence shell like the nearest noble gas. The main bond types are ionic, covalent, and metallic. Bond energy and bond length also help explain how strong a bond is. An ionic bond forms from electrostatic attraction between cations and anions. In many cases, one atom transfers electrons to another atom, and the ions form from that transfer. Ionic bonds have no defined direction because the attraction spreads evenly through three-dimensional space. A...

polar covalent bonds

Electronegativity in Polar Covalent Bonds

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valence bond theory and hybridized orbitals

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Covalent Bond Overlap and Orbital Hybridization

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mo theory and covalent bonding

Bond Order and Molecular Orbitals

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intermolecular forces and physical properties

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solubility

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Solution formation depends on how solutes and solvents interact. A solution is a homogeneous mixture made of a solvent, which is the larger part, and a solute, which is the smaller part. The physical state of a solution is usually the same as the solvent. Concentration is often described as dilute for a low amount of solute or concentrated for a high amount of solute. When a solute dissolves, its particles are surrounded by solvent species. This process is called solvation. If water is the...

introduction to functional groups

Functional Groups and Organic Molecules

Functional groups are groups of atoms with specific chemical properties that appear within organic molecules. They are sometimes shown as "R." These groups sit along the carbon backbone of macromolecules, which can form chains or rings of carbon atoms. Functional groups help functionalize a compound. That means they can give the molecule different physical and chemical properties. In organic chemistry, this change in group structure can strongly affect how a compound behaves. Common...

overview of advanced functional groups

Advanced Functional Groups in Organic Chemistry

Advanced functional groups are atom clusters in organic molecules that give those molecules specific chemical properties. They are sometimes shown as "R" in formulas. By changing the atoms attached to a carbon skeleton, a functional group can make a compound behave differently in physical and chemical reactions. This topic covers several major classes of organic compounds with advanced functional groups. Aromatic hydrocarbons include benzene. Phenol is another example and is also called...

key terms and concepts

Explore ionic, covalent, and metallic bonds, plus bond energy and bond length. Learn how bond type affects strength in high school chemistry.

Chemical Bonds: Types and Strength | JoVE K12

organic chemistry

JoVE Core Organic Chemistry explains basic concepts of stereochemistry, reactions, and mechanisms using concise and easy-to-understand animated video lessons. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

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9-12

Physical Geology

Minerals

Chemical bonding (ionic, covalent, metallic)

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CHEM1.PS2.1

Virginia  Standards of Learning

HIgh School

Physics

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Minnesota Academic Standards in Science

1.1.1 9L.4.2.1.1

3.1.1 9C.2.2.1.2

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Chemical Bonds: Types and Strength

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