Name: lewis structures, bonds, and formal charge
Uploaded: 2025-05-22T09:05:32.000Z
Duration: 2 min 19 s
Channel: JoVE

K12 Standards

Tennessee Academic Standards

High School

Chemistry

Matter and Its Interactions

CHEM1.PS1.12

Lewis Structures and Formal Charges

루이스 구조는 원자 사이의 화학 결합의 단순화 표현이다. 4개의 원자 전자를 가진 2개의 탄소 원자가 각각 1개의 원자 전자를 가진 4개의 수소 원자에 의해 포위되는 에테인을 고려하십시오. 따라서, 에테인은 총 12개의 용맹 전자를 가지고 있다.
2개의 탄소 원자에 대한 옥텟과 4개의 수소 원자에 대한 듀엣을 만족시키기 위해 24개의 전자가 필요합니다. 따라서 12개의 전자는 원자 간에 공유되어야 합니다. 12개의 전자만 사용할 수 있는 전자는 모든 원자가 안정적인 전자 구성에 도달할 수 있도록 전자를 접합해야 합니다.
때로는, 다원자 구조의 원자는 원자 전자의 표준 수를 전시하지 않습니다. 이러한 경우, 비제로공식 전하F는비정상적인 원자와 연관된다. 공식적인 전하는 중립 원자에 있는 원자 전자의 수와 동일합니다 그 원자에 결합 및 공유되지 않은 전자의 수를 뺀.
예를 들어, 암모늄 이온에서, 각 수소 원자는 중립 형태로 하나의 원자 전자를 가지고 있으며 단일 결합에 의해 결합되어 공식적인 충전을 0으로 산출합니다.
이것은 일반적인 5개의 원자 전자 대신 4개의 원자 전자로 질소 원자를 남깁니다. 전자 가 하나 없기 때문에, 그것은 1 플러스의 공식적인 충전을 부담. 따라서, 암모늄 이온에 대한 전체 충전은 1 플러스입니다.
안정적인 구성은 일반적으로 공식적인 요금을 최소화합니다. 일부 더 큰 원소의 경우, 옥텟은 8개 이상의 전자를 공유하여 공식적인 충전이 적은 구성에 도달할 수 있습니다.
예를 들어, 황 삼산화수소의 황 원자는 주변 산소 원자와 단일 및 이중 결합을 형성할 수 있다. 그러나 원자에 대한 전체 공식 요금을 줄이기 때문에 이중 채권 배열이 바람직합니다.
옥텟 규칙에 대한 다른 예외는 옥텟을 달성하는 데 공식적인 전하가 필요하기 때문에 8개가 아닌 6개의 공유 전자의 표적이 되는 붕소 베어링 화합물을 포함한다.

<a href="https://openstax.org/books/chemistry-2e/pages/7-3-lewis-symbols-and-structures"에서 발췌>Openstax, Chemistry 2e, Section 7.3: Lewis Symbols and Structures</a> 및 <a href="https://openstax.org/books/chemistry-2e/pages/7-4-formal-charges-and-resonance">Openstax, Chemistry 2e, Section 7.4: Formal Charges and Resonance에서 발췌</a>.

루이스 구조와 형식 전하

루이스 기호는 분자와 다원자 이온의 결합을 설명하는 그림인 루이스 구조에 표시되는 공유 결합의 형성을 나타내는 데 사용될 수 있습니다. 주기율표는 원자의 원자가 전자 수와 옥텟에 도달하기 위해 형성될 결합 수를 예측하는 데 사용할 수 있습니다. 아르곤, 헬륨과 같은 18족 원소는 전자 구성이 채워져 있어 화학 결합에 거의 참여하지 않습니다. 그러나 브롬이나 요오드와 같은 17족 원자는 옥텟에 도달하기 위해 단 하나의 전자만이 필요합니다. 따라서 17족에 속하는 원자는 단일 공유 결합을 형성할 수 있습니다. 16족의 원자는 옥텟에 도달하기 위해 두 개의 전자가 필요합니다. 따라서 이는 두 개의 공유 결합을 형성할 수 있습니다. 마찬가지로 14족에 속하는 탄소는 한 옥텟에 도달하려면 4개의 전자가 더 필요합니다. 따라서 탄소는 4개의 공유 결합을 형성할 수 있습니다.

염소 분자의 루이스 구조를 생각해 보세요.

<img alt="Figure1" src="/files/ftp_upload/11681/PTfigure_1.svg" style="text-align: center; height: 30px;">

Cl–Cl의 루이스 구조는 각 Cl 원자가 결합에 사용되지 않는 전자쌍 3개(고립쌍이라고 함)와 공유 전자쌍 1개(원자 사이에 기록됨)를 가지고 있음을 나타냅니다. 대시(또는 선)는 때때로 공유된 전자쌍을 나타내는 데 사용됩니다.

단일 공유 전자쌍을 단일 결합이라고 합니다. 각 Cl 원자는 8개의 원자가 전자와 상호 작용합니다. 6개는 고립 전자쌍이고 2개는 단일 결합에 있습니다. 그러나 필요한 옥텟을 달성하려면 한 쌍의 원자가 두 개 이상의 전자 쌍을 공유해야 할 수도 있습니다.

CH2O(포름알데히드)의 탄소 원자와 산소 원자 사이처럼 두 개의 전자 쌍이 한 쌍의 원자 사이에 공유될 때 이중 결합이 형성됩니다.

<img alt="Figure2" src="/files/ftp_upload/11681/PTfigure_2.svg" style="text-align: center; height: 60px;">

일산화탄소(CO)처럼 3개의 전자쌍이 한 쌍의 원자에 의해 공유될 때 삼중 결합이 형성됩니다.

<img alt="Figure3" src="/files/ftp_upload/11681/PTfigure_3.svg" style="text-align: center; height: 20px;">

분자 내 원자의 형식 전하는 결합의 전자가 원자 사이에 고르게 분포되어 있는 경우 원자가 가질 수 있는 가상 전하입니다. 형식 전하는 중성 원자의 원자가 전자 수에서 비결합 전자 수와 원자의 결합 수(또는 결합 전자 수의 절반)의 합을 빼서 계산할 수 있습니다.

형식 전하 = # 원자가 껍질 전자(자유 원자) − # 고립전자쌍 − # 결합

형식 전하 계산은 전체 구조에 대한 형식 전하 합계를 결정하여 다시 확인할 수 있습니다. 중성 분자에 있는 모든 원자의 형식 전하의 합은 0이어야 합니다. 이온의 형식 전하의 합은 이온의 전하와 같아야 합니다. 원자에 대해 계산된 형식 전하는 분자 내 원자의 실제 전하가 아니라는 점을 기억하세요. 형식 전하는 유용한 장부기록 절차일 뿐 실제 전하의 존재를 나타내는 것은 아닙니다.

루이스 기호는 공유 결합의 형성을 나타내는 데 사용할 수 있으며, 이는 루이스 구조(Lewis structures)에 표시되어 있습니다.

Education

교육

JoVE Core

Organic Chemistry

유기 화학

Unit 1

제1단원

Covalent Bonding and Structure

공유 결합과 구조

KEY TERMS AND CONCEPTS

주요 용어 및 개념

lewis structures, bonds, and formal charge

Lewis structures show how atoms share electrons in covalent bonds and in polyatomic ions. Lewis symbols help draw these structures, and the periodic table helps predict how many valence electrons an atom has and how many bonds it can form to reach an octet.

Group 18 elements, such as argon and helium, already have filled electron configurations. They rarely take part in chemical bonding. Atoms in group 17, such as bromine and iodine, need one more electron to reach an octet, so they can form one covalent bond. Atoms in group 16 need two electrons, so they can form two covalent bonds. Carbon is in group 14 and needs four more electrons, so it can form four covalent bonds.

The chlorine molecule is a simple example of a Lewis structure. Each Cl atom has three lone pairs, which are electron pairs not used in bonding, and one shared pair between the atoms. A dash or line can show this shared pair, so the bond can be written as Cl–Cl. A single shared pair is a single bond, and each chlorine atom reaches eight valence electrons when its lone pairs and bond are counted.

Some atoms must share more than one pair of electrons to complete an octet. A double bond forms when two pairs of electrons are shared, as in formaldehyde, CH2O, between carbon and oxygen. A triple bond forms when three electron pairs are shared, as in carbon monoxide, CO. These bond types help show how atoms connect in a molecule.

Formal charge is a bookkeeping tool for Lewis structures. It is the hypothetical charge an atom would have if bonding electrons were shared evenly. To calculate it, subtract the number of lone pair electrons and the number of bonds from the number of valence shell electrons in the free atom. The formal charges in a neutral molecule must add to zero, and the formal charges in an ion must add to the ion’s charge. Even so, formal charge is not the same as actual charge on an atom.

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gas-laws-boyle-s-gay-lussac-charles-avogadro-s-and-ideal-gas-law

Gas Laws: Boyle's, Gay-Lussac, Charles', Avogadro's, and Ideal Gas Law

Through experiments, scientists established the mathematical relationships between pairs of variables, such as pressure and temperature, pressure and ...

kinetic-molecular-theory-molecular-velocities-temperature-kinetic

Kinetic Molecular Theory: Molecular Velocities, Temperature, and Kinetic Energy

The kinetic molecular theory qualitatively explains the behaviors described by the various gas laws. The postulates of this theory may be applied in a ...

Kinetic Theory of an Ideal Gas

A mole is defined as the amount of any substance that contains as many molecules as there are atoms in exactly 12 grams of carbon-12. An Italian scientist ...

applications-of-the-ideal-gas-law-molar-mass-density-and-volume

Applications of the Ideal Gas Law: Molar Mass, Density, and Volume

The volume occupied by one mole of a substance is its molar volume. The ideal gas law, PV = nRT, &nbsp;suggests that the volume of a given quantity of gas ...

Conduct investigations to explore and characterize the behavior of gasses (pressure, volume, and temperature), develop models to represent this behavior, and construct arguments to explain this behavior. Evaluate the relationship (qualitative and quantitatively) at STP between pressure and volume (Boyle's Law), temperature and volume (Charles' Law), temperature and pressure (Gay-Lussac Law) and moles and volume (Avogadro's Law), and evaluate and explain these relationships with respect to kinetic molecular theory. Be able to understand, establish, and predict the relationships between volume, temperature, and pressure using combined gas law both qualitatively and quantitatively. EXPLANATION: When exploring the behavior of gasses, it is important to consider experimental design. Experiments used to show the relationships between these sets of variables should include one independent and one dependent variable. Other variables should be held constant. Pressure should serve as the dependent variable because it cannot be manipulated directly. Avogadro's Law can be used to relate the amount of gas in two different containers in lieu of knowing actual number of gas particles in an individual container. Individual demonstrations can be performed to explore each of the different gas laws.

CHEM1.PS1.5

Ideal Gas Equation

The ideal gas equation is an equation of state that relates the state variables pressure, volume, temperature, and the number of moles of a hypothetical ...

Source: Laboratory of Dr. Andreas Z&#252;ttel - Swiss Federal Laboratories for Materials Science and Technology
The ideal gas law describes the behavior ...

real-gases-effects-intermolecular-forces-molecular-volume-deriving

Real Gases: Effects of Intermolecular Forces and Molecular Volume Deriving Van der Waals Equation

Thus far, the ideal gas law, PV = nRT, has been applied to a variety of different types of problems, ranging from reaction stoichiometry and empirical and ...

chemical-stoichiometry-gases-using-ideal-gas-law-to-determine

Chemical Stoichiometry and Gases: Using Ideal Gas Law to Determine Moles

Chemical stoichiometry describes the quantitative relationships between reactants and products in chemical reactions.

In addition to measuring quantities ...

pV-Diagrams

The pV diagram, which is a graph of pressure versus volume of the gas under study, is helpful in describing certain aspects of the substance. When the ...

Use the ideal gas law, PV = nRT, to algebraically evaluate the relationship among the number of moles, volume, pressure, and temperature for ideal gases. EXPLANATION: If students have collected data during investigations for CHEM1.PS1.5, these data can then be used to linearize. With pressure assigned as the dependent variable and plotted against (moles) (temperature)/volume, the slope of the graph will be the gas constant, yielding the ideal gas law. After developing the mathematical model, this model can be used to make predictions for other systems.

CHEM1.PS1.6

Separation of Mixtures via Precipitation

Source: Laboratory of Dr. Ana J. Garc&#237;a-S&#225;ez &#8212; University of T&#252;bingen
Most samples of interest are mixtures of many different ...

States of Matter and Phase Changes

The internal energy of a substance&#8212;the total kinetic energy of all its molecules and the potential energy of their associated forces&#8212;depends ...

Distillation: Vapor&ndash;Liquid Equilibria

Distillation is a separation technique that takes advantage of the boiling point properties of disparate elements in a mixture. To perform distillation, ...

Filtration

Filtration is the physical separation of solids from a fluid using a filtration medium.
The filtration medium is chosen depending on the purpose of ...

Centrifugation

Centrifugation is a method of separating suspended particles from a liquid by spinning in a centrifuge at a high number of revolutions per minute.
...

Sublimation

Sublimation is the direct phase transformation from the solid to the gaseous phase, bypassing the liquid state.
For example, solid carbon dioxide, or dry ...

recrystallization-solidsolution-equilibria

Recrystallization: Solid&ndash;Solution Equilibria

Recrystallization is a purification technique used to separate impurities from solid compounds. In this technique, no chemical reactions occur. Instead, ...

Precipitation and Co-precipitation

Precipitation and coprecipitation techniques can be applied to separate a mixture of ions.
When different ions form sparingly soluble salts with the same ...

Electrodeposition

During electrodeposition, ions are separated from a solution by deposition on an electrode in an electrolytic cell.
While reduction occurs at the cathode ...

extraction-partition-and-distribution-coefficients

Extraction: Partition and Distribution Coefficients

The distribution law or Nernst&#39;s distribution law is the law that governs the distribution of a solute between two immiscible solvents. This law, also ...

Extraction: Effects of pH

Consider a weak base,&#160; B, with a partition coefficient, K, between the organic and aqueous phases.&#160;&#160;
While organic bases are usually more ...

Extraction: Advanced Methods

Metal ions can be separated by complexation with organic ligands to form uncharged chelates.
The chelating agent must contain hydrophobic groups and ...

Chromatography: Introduction

Chromatography is a technique used to separate compounds based on differences of partitioning between two phases, the stationary phase and the mobile ...

Dialysis

Dialysis separates desired analyte ions or molecules from unwanted molecules, or &#39;interferents&#39;, by allowing the sample solution to diffuse ...

Analyze solutions to identify solutes and solvents, quantitatively analyze concentrations (molarity, percent composition, and ppm), and perform separation methods such as evaporation, distillation, and/or chromatography and show conceptual understanding of distillation. Construct argument to justify the use of certain separation methods under different conditions. EXPLANATION: In seventh grade, students developed an understanding that chemical and physical properties of a sample of matter could be used to identify a substance. Building on this understanding, students now explore the use of these physical and chemical properties to separate mixtures. Analysis of the substances is performed to aid in further discussion and facilitate further quantitative analysis.

CHEM1.PS1.7

Lewis Structures, Bonds, and Formal Charge

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