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

Lewis yapıları, atomlar arasındaki kimyasal bağların basitleştirilmiş temsilleridir. Her biri dört değerlik elektronuna sahip iki karbon atomunun, her biri bir değerlik elektronuna sahip dört hidrojen atomu ile çevrili olduğu eteni düşünün. Bu nedenle, etenin toplam on iki değerlik elektronu vardır.
İki karbon atomu için oktetleri ve dört hidrojen atomu için duetleri sağlamak için yirmi dört elektron gerekir. Bu nedenle, atomlar arasında on iki elektron paylaşılmalıdır. Sadece on iki elektron mevcut olduğundan, tüm atomların kararlı bir elektronik konfigürasyona ulaşmasına izin vermek için hepsinin bağ elektronları olması gerekir.
Bazen, çok atomlu yapılardaki atomlar standart değerlik elektron sayısını göstermezler. Bu gibi durumlarda, sıfırdan farklı bir resmi yük olan F, anormal atom ile ilişkilidir. Resmi yük, nötr atomdaki değerlik elektronlarının sayısı eksi o atomdaki bağların ve paylaşılmamış elektronların sayısına eşittir.
Örneğin, amonyum iyonunda, her hidrojen atomu nötr formunda bir değerlik elektronuna sahiptir ve tek bir bağ ile bağlanır ve resmi bir sıfır yükü verir.
Bu, nitrojen atomunu normal beş değerlik elektronu yerine dört değerlik elektronu ile bırakır. Bir elektronu eksik olduğu için, bir artı resmi bir yük taşır. Bu nedenle, amonyum iyonu üzerindeki toplam yük bir artıdır.
Kararlı yapılandırmalar genellikle resmi ücretleri en aza indirir. Bazı daha büyük elementler için, sekizli, daha az resmi yüke sahip bir konfigürasyona ulaşmak için sekizden fazla elektronu paylaşacak şekilde genişletilebilir.
Örneğin, kükürt trioksitteki kükürt atomu, çevredeki oksijen atomları ile hem tek hem de çift bağlar oluşturabilir. Bununla birlikte, atom üzerindeki genel resmi yükü azalttığı için çift bağ düzenlemesi tercih edilir.
Oktet kuralının diğer istisnaları, sekiz yerine altı paylaşılan elektron hedefine sahip olan bor içeren bileşikleri içerir, çünkü bir oktet elde etmek resmi bir yük gerektirir.

<a href="https://openstax.org/books/chemistry-2e/pages/7-3-lewis-symbols-and-structures">Openstax, Chemistry 2e, Section 7.3: Lewis Sembolleri ve Yapıları and <a href="https://openstax.org/books/chemistry-2e/pages/7-4-formal-charges-and-resonance"> </a> Openstax, Chemistry 2e, Section 7.4: Official Loads and Resonance bölümlerinden uyarlanmıştır</a>.

lewis yapıları ve formal yükler

Lewis sembolleri, moleküllerin ve çok atomlu iyonların bağlanmasını ifade eden Lewis yapı-çizimlerinde gösterilen kovalent bağların oluşumunu belirtmek için kullanılabilir. Periyodik tablo, bir atomdaki değerlik elektronlarının sayısını ve bir oktete ulaşmak için oluşacak bağların sayısını tahmin etmek için kullanılabilir. Argon ve helyum gibi Grup 18 elementleri dolu elektron konfigürasyonlarına sahiptir ve bu nedenle kimyasal bağlanmaya nadiren katılırlar. Bununla birlikte, brom veya iyot gibi grup 17'deki atomların oktete ulaşmak için yalnızca bir elektrona ihtiyacı vardır. Dolayısıyla grup 17'ye ait atomlar tek bir kovalent bağ oluşturabilir. Grup 16'nın atomlarının bir oktete ulaşmak için iki elektrona ihtiyacı vardır; dolayısıyla iki kovalent bağ oluşturabilirler. Benzer şekilde 14. gruba ait olan karbonun da bir oktete ulaşmak için dört elektrona daha ihtiyacı vardır; böylece karbon dört kovalent bağ oluşturabilir.

Klor molekülünün Lewis yapısını düşünün:

<img alt="Figure1" src="/files/ftp_upload/11681/PTfigure_1.svg" style="text-align: center; height: 30px;">

Lewis yapısı, her Cl atomunun, bağlanmada kullanılmayan üç çift elektrona (yalnız çiftler denir) ve paylaşılan bir elektron çiftine (atomlar arasında yazılı) sahip olduğunu gösterir. Paylaşılan bir elektron çiftini belirtmek için bazen kısa çizgi (veya çizgi) kullanılır: Cl–Cl

Paylaşılan tek bir elektron çiftine tek bağ denir. Her Cl atomu sekiz değerlik elektronu ile etkileşime girer: altısı yalnız çiftlerde ve ikisi tekli bağda. Bununla birlikte, gerekli okteti elde etmek için bir çift atomun birden fazla elektron çiftini paylaşması gerekebilir.

 CH2O 'daki (formaldehit) karbon ve oksijen atomları arasında olduğu gibi, bir çift atom arasında iki çift elektron paylaşıldığında bir çift bağ oluşur.

<img alt="Figure2" src="/files/ftp_upload/11681/PTfigure_2.svg" style="text-align: center; height: 60px;">

Karbon monoksitte (CO) olduğu gibi, üç elektron çifti bir çift atom tarafından paylaşıldığında üçlü bağ oluşur.

<img alt="Figure3" src="/files/ftp_upload/11681/PTfigure_3.svg" style="text-align: center; height: 20px;">

Bir moleküldeki bir atomun formal yükü, eğer bağlardaki elektronlar atomlar arasında eşit olarak dağılmışsa atomun sahip olacağı varsayımsal yüktür. Formal yük, nötr atomun değerlik elektronlarının sayısından, bir atomdaki bağ yapmayan elektron sayısı ve bağ sayısının toplamının (veya bağ elektronlarının sayısının yarısının) çıkarılması ile hesaplanabilir:

Formal yük = # değerlik kabuğu elektronları (serbest atom) − # yalnız çift elektronlar − # bağlar

Resmi ücret hesaplamaları, tüm yapı için resmi ücretlerin toplamı belirlenerek iki kez kontrol edilebilir. Nötr bir moleküldeki tüm atomların formal yüklerinin toplamı sıfır olmalıdır; Bir iyondaki formal yüklerin toplamı iyonun yüküne eşit olmalıdır. Bir atom için hesaplanan formal yükün, moleküldeki atomun gerçek yükü olmadığını unutmayın. Resmi ücret yalnızca yararlı bir defter tutma prosedürüdür; gerçek suçlamaların varlığını göstermez.

Lewis Yapıları ve Formal Yükler

Lewis sembolleri, Lewis yapılarında gösterilen kovalent bağların oluşumunu belirtmek için kullanılabilir - bağı tanımlayan çizimler ...

Education

JoVE Core

Organic Chemistry

Organik Kimya

Unit 1

Ünite 1

Covalent Bonding and Structure

Kovalent Bağlanma ve Yapı

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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.

Lewis Structures, Bonds, and Formal Charge

what is organic chemistry?

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...

electronic structure of atoms

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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How Electrons Fill Atomic Orbitals

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chemical bonds

Chemical Bonds: Types and Strength

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polar covalent bonds

Electronegativity in Polar Covalent Bonds

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lewis structures and formal charges

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...

vsepr theory

Molecular Shapes from Electron Pairs

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molecular geometry and dipole moments

Predicting Shape and Molecular Polarity

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resonance and hybrid structures

Resonance in Nitrite and Carbonate Ions

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valence bond theory and hybridized orbitals

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Covalent Bond Overlap and Orbital Hybridization

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Bond Order and Molecular Orbitals

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intermolecular forces and physical properties

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introduction to functional groups

Functional Groups and Organic Molecules

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Advanced Functional Groups in Organic Chemistry

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key terms and concepts

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Lewis Structures, Bonds, and Formal Charge | JoVE K12

organic chemistry

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Stoichiometry, Product Yield, and Limiting Reactants

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...

Understand and be prepared to use values specific to chemical processes: the mole, molar mass, molarity, and percent composition. EXPLANATION: During the early and mid-1800s, a tremendous amount of early research poured into building an understanding of the way that atoms combine. This work required analysis of the percent composition of different substances. Joseph Proust's work with tin oxides led him to publish his law of definite proportions noting that a given pure substance will have a constant ratio for the combination of elements making up the substance. Building on Proust's work, John Dalton published his law of multiple proportions and atomic theory noting that multiple patterns exist for the way that atoms combine, yet the combining atoms are invariable. Meanwhile Amedeo Avogadro hypothesizes that given equal pressures and temperatures, two equal volumes of gas will contain equal numbers of atoms. Acknowledging that the exact number of atoms was unknown in these gaseous volumes, the Latin word "mole" was used. "Mole" translates to "lump" recognizing the ambiguous quantity of gas. A number of attempts have been undertaken historically to quantify the mole. Robert Millikan's oil drop experiment revealed the change of a single electron, which could then be divided into Faraday's Constant for the charge of a mole of electrons. Dividing the charge of a mole of electrons by the charge of a single electron yields the number of electrons in a mole, $6.022\times10^{\wedge}23$. Students should be familiar with how to translate between the given quantities. Student's first use atomism/Dalton's atomic theory in third grade noting that matter is made up of particles too small to be seen. This the first time where students will undertake the process of counting these invisible particles. Electrolysis of water provides a tangible experience to demonstrate the constituent parts of water, though the definite proportions of water may not be easily seen due to the solubility of the gasses produced. The concept of relative mass can be explored by comparing small groups of like items. For example, relative masses of beans can be compared with pinto, white, and black beans. If bags are created with equal numbers of like beans, students can develop a concept of why the smallest bean will have a relative mass of 1, analogous to hydrogen.

CHEM1.PS1.1

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The Atomic Theory of Matter

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Chemical Reactions

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Demonstrate that atoms, and therefore mass, are conserved during a chemical reaction by balancing chemical reactions. EXPLANATION: Standard 7.PS1.4 explores the idea that chemical reactions are rearrangements of atoms, and students undertake the process of balancing chemical reactions with that standard in seventh grade. The introduction of molar masses in high school makes an explicit connection between the number of atoms, as previously investigated, and the actual masses of the atoms, permitting the collection of more concrete evidence for the conservation of mass in chemical reactions.

CHEM1.PS1.2

Reaction Yield

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Limiting Reactant

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Chemical Equilibria: Systematic Approach to Equilibrium Calculations

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Perform stoichiometric calculations involving the following relationships: mole- mole; mass-mass; mole-mass; mole- particle; and mass- particle. Show a qualitative understanding of the phenomenon of percent yield, limiting, and excess reagents in a chemical reaction through pictorial and conceptual examples. (states of matter liquid and solid; excluding volume of gasses). EXPLANATION: This standard builds on the idea that balancing chemical reactions provides evidence for conservation of mass and that the behavior of atoms follows predictable patterns. Students now have the opportunity to utilize this understanding as they perform and evaluate chemical reactions. (The concepts of limiting reagent and percent yield are presented; however, students are not expected to determine these values algebraically. Use of molar volume in stoichiometric processes is beyond the scope of this standard.)

CHEM1.PS1.3

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Chemical Reactions in Aqueous Solutions

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Oxidation&ndash;Reduction Reactions

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Types of Chemical Reactions: Exchange and Reversible

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CHEM1.PS1.4

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Kinetic Molecular Theory and Gas Laws Explain Properties of Gas Molecules

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Ideal Gas Law

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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

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pV-Diagrams

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CHEM1.PS1.6

Separation of Mixtures via Precipitation

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Distillation: Vapor&ndash;Liquid Equilibria

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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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