Name: how bond polarity shapes molecular dipoles
Uploaded: 2020-09-03T13:38:28.000Z
Duration: 2 min 48 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

NC K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.3.1

bond-polarity-dipole-moment-and-percent-ionic-character

Bond Polarity, Dipole Moment, and Percent Ionic Character

نوع الروابط الكيميائية سواء كانت تساهمية غير القطبية،تساهمية قطبية،أو أيونية،إلى حد كبير،يحدده الاختلاف في السالبيةالكهربية بين ترابط الذرات وطول روابطها. في البروم،تكون الرابطة بين ذرتي البروم،غير قطبية حيث الاختلاف في السالبيةالكهربية بينهما صفر. في بروميد الهيدروجين،تكون الرابطة تساهمية قطبية،حيث البروم الأكثر سالبيةكهربية،يجذب الكثافةالإلكترونية بعيدًا عن ذرة الهيدروجين الأقل سالبيةكهربية.في بروميد البوتاسيوم،تكون الرابطة عبارة عن رابطة أيونية نتيجة للاختلاف الأكبر في السالبيةالكهربية،مما يؤدي الى نقل الإلكترون الكامل،من البوتاسيوم إلى البروميد. عندما يتساوي جسيمان،ولكن يتعاكسا فى الشحنات،ويتم فصلهما بمسافة،يتكون ثنائي-القطب. المقياس الكمي لثنائي-القطب يسمى عزم ثنائي-القطب،و يمثله الحرف mu وهو حاصل ضرب مقدار الشحنات،Q،يبلغ بال(كولوم)والمسافة بين الشحنات،r،يبلغ بالأمتار.يُعطى عزم ثنائي-القطب بوحدات debye،حيث،واحد debye يساوي 3.34 10 30 كولوم متر. ما إذا كان المركب قطبيًا تساهميًا أو أيونيًا يمكن تحديد ذلك،عن طريق حساب النسبة المئوية للطابع الأيوني،وهي نسبة،عزم ثنائي-القطب للرابطة،إلى عزم ثنائي-القطب،بافتراض النقل الكامل للإلكترون. الروابط ذات الطابع الأيوني الأكثر من 50٪تعتبر أيونية.باعتبار فلوريد الهيدروجين،حيث ذرات الهيدروجين والفلور مفصولة بمسافة 92 pm. إذا كانت الرابطة أيونية،فإن عزم ثنائي-القطب يتم حسابه على افتراض نقل الإلكترون بالكامل. يتم ضرب شحنة الإلكترون في المسافة بين الذرات والقيمة التي تم الحصول عليها تقسم على debye واحد،لينتج عزم ثنائي-القطب 4.41 debye.ومع ذلك،فإنّالقياس التجريبي لعزم ثنائي-القطب لفلوريد الهيدروجين هو 1.18 debye. لذلك،لتحديد النسبة المئوية للطابع الأيوني لفلوريد الهيدروجين،يتم تقسيم القيمة المقاسة 1.18 debye علي 4.41 debye،مما يعطي طابعًا أيونيًا بنسبة 41 و نظراًلأنّالنسبة المئوية للطابع الأيوني لفلوريد الهيدروجين أقل من 50٪إنها تكون رابطة تساهمية قطبية.

قطبية الروابط، العزم ثنائي القطب، والنسبة الأيونية

<h4> قطبية الروابط </h4> توفر القيمة المطلقة للاختلاف في الكهربية (ΔEN) لذرتين مترابطتين مقياساً تقريبياً للقطبية المتوقعة في الرابطة ، وبالتالي نوع الرابطة. عندما يكون الاختلاف صغيراً جداً أو صفراً ، تكون الرابطة تساهمية وغير قطبية. عندما تكون كبيرة ، تكون الرابطة قطبية تساهمية أو أيونية. القيم المطلقة للاختلافات الكهرسلبية بين الذرات في الروابط H–H, H–Cl, و Na–Cl هي 0 (غير قطبية) ، 0.9 (تساهمية قطبية) ، و 2.1 (أيونية)، على التوالي.  تختلف درجة مشاركة الإلكترونات بين الذرات من متساوية تماماً (رابطة تساهمية نقية) إلى عدم تساويها مطلقاً (رابطة أيونية). <ul><li> على سبيل المثال، تمتلك ذرات H و F في HF فرقاً كهرسلبياً قدره 1.9 ، بينما يختلف اختلاف ذرات N و H في NH3 بمقدار 0.9 ، إلا أن كلا المركبين يشكلان روابط تعتبر تساهمية قطبية. </li><li> وبالمثل، فإن ذرات Na و Cl في NaCl لها فرق في الكهرسلبية يبلغ 2.1، ويوجد اختلاف في ذرات Mn و I في MnI2 بمقدار 1.0، ومع ذلك فإن كلتا المادتين تشكلان مركبات أيونية. </li></ul> أفضل دليل على الطابع التساهمي أو الأيوني للرابطة هو النظر في أنواع الذرات المعنية ومواقعها النسبية في الجدول الدوري.  <ul><li> الروابط بين اثنين من اللامعادن تساهمية بشكل عام. </li><li> غالباً ما يكون الترابط بين المعدن واللامعادن أيونياً. </li></ul> تحتوي بعض المركبات على كل من الروابط التساهمية والأيونية. الذرات في الأيونات متعددة الذرات ، مثل OH–, NO3−,  و NH4+ ، يتم تجميعها معاً بواسطة روابط تساهمية قطبية. ومع ذلك، فإن هذه الأيونات متعددة الذرات تشكل مركبات أيونية عن طريق الاندماج مع أيونات الشحنة المعاكسة. على سبيل المثال، تحتوي نترات البوتاسيوم، KNO3، على أنيون K+ ومتعدد الذرات أنيون NO3− . وبالتالي، فإن الترابط في نترات البوتاسيوم يكون أيونياً، وينتج عن التجاذب الكهروستاتيكي بين الأيونات K+ and NO3− ، وكذلك رابطة تساهمية بين ذرات النيتروجين والأكسجين في NO3−.<h4> القطبية الجزيئية والعزم ثنائي القطب </h4> كما نوقش سابقاً، تربط الروابط التساهمية القطبية ذرتين بكهرسلبية مختلفة، تاركة ذرة واحدة مع شحنة موجبة جزئية (δ+) والذرة الأخرى بشحنة سالبة جزئية (δ–)، حيث أن الإلكترونات سحبت نحو ذرة أكثر كهرسلبية. يؤدي فصل الشحنة هذا إلى نشوء عزم رابطة ثنائي القطب. يتم تمثيل حجم عزم ثنائي القطب بالحرف اليوناني mu (µ) ويتم الحصول عليه بالصيغة الموضحة هنا، حيث Q هي مقدار الشحنات الجزئية (يحددها فرق الكهرسلبية) و r هي المسافة بين الشحنات: <img alt="Eq1" src="https://www.jovecore.com/CDNSource/lessons/1062/1062_Equations-01.png" style="height: 40px;" /> يمكن تمثيل لحظة الرابطة هذه كسهم توجيه، وكمية لها اتجاه وحجم. يتم عرض المتجهات ثنائية القطب على شكل أسهم تشير جنبًا إلى جنب مع الرابطة من الذرة الأقل كهرسلبية باتجاه الذرة الأكثر كهرسلبية. يتم رسم علامة زائد صغيرة على الطرف الأقل سلبيًا للإشارة إلى النهاية الموجبة جزئيًا للرابطة. يتناسب طول السهم مع مقدار فرق الكهربية بين الذرتين. 
 
 قد يكون في الجزيء كله أيضاً فصل في الشحنة، اعتماداً على هيكله الجزيئي وقطبية كل من روابطه. في حالة وجود فصل الشحنة هذا، يُقال أن الجزيء جزيء قطبي (أو ثنائي القطب) ؛ خلاف ذلك، يُقال أن الجزيء غير قطبي. تقيس العزم ثنائي القطب مدى صافي فصل الشحنة في الجزيء ككل. يتم تحديد عزم ثنائي القطب عن طريق إضافة لحظات الرابطة في الفضاء ثلاثي الأبعاد ، مع مراعاة التركيب الجزيئي. بالنسبة للجزيئات ثنائية الذرة ، توجد رابطة واحدة فقط ، لذلك تحدد عزم الرابطة ثنائي القطب القطبية الجزيئية. الجزيئات ثنائية النواة متجانسة النواة مثل Br2 و N 2 ليس لها فرق في الكهرسلبية، لذا فإن عزمها ثنائي القطب هو صفر. بالنسبة للجزيئات غير المتجانسة مثل ثاني أكسيد الكربون، هناك عزم ثنائي القطب صغير. بالنسبة إلى التردد العالي، هناك عزم ثنائي القطب أكبر نظراً لوجود فرق أكبر في الكهربية. عندما يحتوي الجزيء على أكثر من رابطة، يجب مراعاة الهندسة. إذا تم ترتيب الروابط في جزيء بحيث يتم إلغاء لحظات الرابطة (مجموع المتجه يساوي صفراً)، يكون الجزيء غير قطبي. هذا هو الوضع في CO2. كل من الروابط قطبية ، لكن الجزيء ككل غير قطبي. من بنية لويس، وباستخدام نظرية VSEPR، تم تحديد جزيء CO2 ليكون خطياً مع روابط C=O القطبية على جوانب متقابلة من ذرة الكربون. تلغي لحظات الرابطة لأنها موجهة في اتجاهين متعاكسين. في حالة جزيء الماء، تُظهر بنية لويس مرة أخرى أن هناك رابطين بذرة مركزية ، ويظهر فرق الكهربية مرة أخرى أن كل من هذه الروابط لها عزم رابطة غير صفري. ومع ذلك، في هذه الحالة، ينحني التركيب الجزيئي بسبب الأزواج المنفردة الموجودة على O، ولا يتم إلغاء لحظتي الرابطة. لذلك، يحتوي الماء على عزم صافي ثنائي القطب وهو جزيء قطبي (ثنائي القطب). هذا النص مقتبس من <a href="https://openstax.org/books/chemistry-2e/pages/7-2-covalent-bonding">Openstax, Chemistry 2e, Chapter 7.2: Covalent Bonding and  Openstax, Chemistry 2e, Chapter 7.6 Molecular Structure and Polarity.</a>

قطبية السندات

توفر القيمة المطلقة للفرق في الكهربية (ΔEN) لذرتين مرتبطتين مقياسا تقريبيا للقطبية التي يجب أن تكون ...

Education

JoVE Core

الكيمياء

واحد

Chemical Bonding: Basic Concepts

الترابط الكيميائي: مفاهيم أساسية

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

how bond polarity shapes molecular dipoles

Bond polarity depends on electronegativity, the ability of an atom to attract shared electrons. The absolute value of the electronegativity difference, or ΔEN, gives a rough guide to bond type. When the difference is very small or zero, the bond is covalent and nonpolar. When it is larger, the bond may be polar covalent or ionic.

Examples show how this works in real compounds. H–H has a ΔEN of 0, so it is nonpolar. H–Cl has a ΔEN of 0.9, so it is polar covalent. Na–Cl has a ΔEN of 2.1, so it is ionic. Even so, ΔEN is only a guide. HF has a ΔEN of 1.9 and NH3 has a ΔEN of 0.9, yet both have polar covalent bonds. NaCl has a ΔEN of 2.1 and MnI2 has a ΔEN of 1.0, yet both are ionic compounds.

The type of atoms in the periodic table is often the best clue. Bonds between two nonmetals are generally covalent. Bonds between a metal and a nonmetal are often ionic. Some compounds include both kinds of bonding. Polyatomic ions such as OH−, NO3−, and NH4+ have polar covalent bonds inside the ion. They form ionic compounds when they combine with ions of the opposite charge. Potassium nitrate, KNO3, is one example. It contains K+ and NO3−, so the attraction between those ions is ionic, while the N–O bonds inside nitrate are covalent.

Polar covalent bonds create partial charges, written as δ+ and δ−. The more electronegative atom pulls the electrons closer, so one end of the bond becomes partially negative and the other becomes partially positive. This charge separation creates a bond dipole moment, symbolized by μ. A dipole is shown as a vector, or arrow, that points from the less electronegative atom toward the more electronegative atom. A small plus sign marks the positive end. A longer arrow means a larger electronegativity difference.

A whole molecule can also have a net dipole moment. That depends on both bond polarity and molecular shape. The dipole moment of the molecule is found by adding the bond moments in three-dimensional space. For diatomic molecules, there is only one bond, so the bond dipole sets the molecular polarity. Homonuclear diatomic molecules such as Br2 and N2 have no electronegativity difference, so their dipole moment is zero. Heteronuclear molecules such as CO have a small dipole moment, and HF has a larger one because its electronegativity difference is larger.

Molecular geometry can make polar bonds cancel. CO2 is linear, so its two polar C=O bond moments point in opposite directions and cancel. The molecule is nonpolar even though its bonds are polar. Water is different. Its Lewis structure shows two bonds to oxygen, and each bond has a nonzero dipole moment. Because the molecule is bent, the bond moments do not cancel. Water therefore has a net dipole moment and is a polar molecule.

How Bond Polarity Shapes Molecular Dipoles

how-bond-polarity-shapes-molecular-dipoles

types of chemical bonds

Chemical Bonding and Bond Properties

Chemical bonding explains how atoms and ions join to form molecules and compounds. American chemist Gilbert N. Lewis pioneered chemical bonding theory with the Lewis model. This model helps explain why bonds form, why some are stronger than others, and why compounds have fixed formulas like H2O instead of H4O. Ionic bonding involves ions, which are atoms or molecules with an electrical charge. A cation is a positive ion formed when a neutral atom loses one or more electrons from its valence...

the born-haber cycle

Predicting Ionic Stability with Lattice Energy

Lattice energy helps explain why ionic compounds are stable. It measures the strength of attraction between positive and negative ions in a crystal. In one common definition, lattice energy is the energy required to separate one mole of an ionic solid into gaseous ions, so it has a positive value. Another definition uses the opposite sign and describes the energy released when gaseous ions form a lattice. When checking data, it is important to confirm which convention is being used. In either...

lewis symbols and the octet rule

Valence Electrons, Lewis Symbols, and Bonding

Chemical bonds form when atoms or ions interact in ways that lower the potential energy of a molecule. Gilbert N. Lewis created a simple model to show bond formation using valence electrons, the electrons in the outer shell. In this model, electrons are shared or transferred to help atoms reach a stable electron configuration. The Lewis model helps describe two common bond types. An ionic bond forms when electrons move from a metal to a nonmetal. A covalent bond forms when two nonmetals share...

electronegativity

Electronegativity and Polar Bonds

Electronegativity helps explain why some covalent bonds are nonpolar and others are polar covalent. It is a measure of how strongly an atom attracts shared electrons toward itself. That pull controls how electron density is distributed in a bond. Linus Pauling proposed the first electronegativity values by studying bond energies in heteronuclear molecules such as hydrogen fluoride. He expected the bond energy of HF to be about the average of the bond energies of H2 and F2, or 296 kJ/mol. The...

ionic bonding and electron transfer

Ionic Compounds and Crystal Lattices

Ionic compounds form when positive and negative ions attract each other. A cation is a positive ion, and it forms when an atom loses one or more valence electrons. An anion is a negative ion, and it forms when an atom gains one or more valence electrons. Compounds made of these ions are called ionic compounds, or salts, and the force between them is an ionic bond. The properties of ionic solids help show how strong this attraction is. They usually form rigid, brittle crystals and have high...

trends in lattice energy: ion size and charge

trends-in-lattice-energy-ion-size-and-charge

Lattice Energy Patterns in Ionic Solids

Lattice energy shows how strongly ions hold an ionic solid together. It is the energy required to separate one mole of a solid into its gaseous ions. For sodium chloride, this process requires 769 kJ per mole. The opposite convention may also be used, where lattice energy is the energy released when gaseous ions form the solid. In either case, a larger magnitude means a more stable ionic compound. For ionic crystals, lattice energy follows a pattern based on charge and ion size. The...

covalent bonding and lewis structures

Shared Electrons in Covalent Molecules

Covalent molecules form when atoms share electrons instead of transferring them. This bonding usually happens between nonmetal atoms with similar tendencies to attract electrons. Because the atoms pull on the electrons in a shared way, the bond is held together by mutual attraction. Covalent compounds often have physical properties that differ from ionic compounds. The attraction between neutral molecules is weaker than the attraction between charged ions. As a result, many covalent compounds...

bond polarity, dipole moment, and percent ionic character

Bond polarity depends on electronegativity, the ability of an atom to attract shared electrons. The absolute value of the electronegativity difference, or ΔEN, gives a rough guide to bond type. When the difference is very small or zero, the bond is covalent and nonpolar. When it is larger, the bond may be polar covalent or ionic. Examples show how this works in real compounds. H–H has a ΔEN of 0, so it is nonpolar. H–Cl has a ΔEN of 0.9, so it is polar covalent. Na–Cl has a ΔEN of 2.1, so it...

lewis structures of molecular compounds and polyatomic ions

lewis-structures-of-molecular-compounds-and-polyatomic-ions

Drawing Lewis Structures with Valence Electron Counts

Drawing Lewis structures starts with counting valence electrons and building the atom arrangement step by step. Valence electrons are the outer-shell electrons that help show how atoms bond. For ions, a positive charge means one electron is removed for each plus sign, and a negative charge means one electron is added for each minus sign. The next step is to sketch the skeleton structure. The least electronegative atom usually goes in the center, while hydrogen is almost never central. Fluorine...

resonance

Resonance Forms in Lewis Structures

Resonance forms in Lewis structures help explain molecules and ions that cannot be shown correctly with just one drawing. In nitrite ion, NO2−, the Lewis structure can be drawn in two ways. The N-O and N=O bonds switch positions in the two drawings, but the atoms stay in the same arrangement. If nitrite really had one single bond and one double bond, the two bond lengths should be different. A double bond is shorter and stronger than a single bond between the same atoms. Experiments show that...

formal charges

Lewis Structures with Formal Charge

Lewis structures can sometimes show more than one reasonable arrangement for a molecule or polyatomic ion. Formal charge helps chemists choose the best Lewis structure when that happens. It is a useful way to compare possible structures in chemistry. Formal charge is the hypothetical charge an atom would have if bonding electrons were shared evenly between the atoms. It can also be found by starting with the valence electrons of the neutral atom, subtracting the nonbonding electrons, and then...

exceptions to the octet rule

Octet Rule Exceptions in Lewis Structures

Some covalent molecules do not follow the octet rule in their Lewis structures. Their central atoms can fall into three groups: odd-electron molecules, electron-deficient molecules, and hypervalent molecules. These cases show why a Lewis structure may not always give every atom eight valence electrons. Odd-electron molecules have an odd number of valence electrons, so one electron remains unpaired. Molecules with an odd number of electrons are called radicals. Nitric oxide, NO, is one example,...

bond energies and bond lengths

How Bond Energy Predicts Reaction Heat

Bond energy helps explain why molecules stay together and how much heat a reaction may release or absorb. A covalent bond is stronger when more energy is needed to separate the atoms. The energy needed to break one specific covalent bond in one mole of gaseous molecules is called bond energy, or bond dissociation energy. For a diatomic molecule, bond energy is the standard enthalpy change for an endothermic reaction that breaks that bond. The H-H bond is a common example. Its bond energy is...

bonding in metals

Electron Sea Model in Metals

Electron sea model explains how metallic bonding holds metals together. In this model, most metal atoms do not have enough valence electrons to form ionic or covalent bonds in the usual way. Their valence electrons are held loosely because metals have low electronegativity, and their ionization energy is low, so electrons are removed easily. When a metal atom loses these outer electrons, it becomes a positively charged metal ion. The freed electrons form a delocalized electron cloud around...

key terms and concepts

Learn how electronegativity, bond dipoles, and molecular shape determine whether a bond or molecule is polar, using examples like HCl, CO2, and water.

How Bond Polarity Shapes Molecular Dipoles | JoVE K12

chemistry

JoVE Core Chemistry brings general chemistry concepts to life using concise and easy-to-understand animated video lessons. Plus, in the scientist-in-action videos, we demonstrate classical and original research experiments performed in today's laboratories worldwide.

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Physical Science

Study Of Matter

Bonding and compounds

Structure And Properties Of Matter

Chemical bonding

Tennessee Academic Standards

High School

Matter and Its Interactions

CHEM1.PS1.13

CHEM1.PS1.14

Virginia  Standards of Learning

HIgh School

CH.3

CH.3.d

Physics

PH.9

PH.9.e

Alabama Course of Study Science

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

9-12.C.2.2.c

9-12.C.2.2.e

Texas Essential Knowledge and Skills

Chemistry and Physics

IPC.7

IPC.7.A

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Structure and Properties of Matter

HS-PS1-3.

HS. Chemical Reactions

HS-PS1-2.

Scientific Laws and Theories

Scientific Laws

In science, a law is defined as a concise, verbal or mathematical, statement that summarizes a vast number of experimental observations. ...

The Scientific Method

Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To ...

Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

Classifying Matter by Composition

Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories &mdash; pure substances and ...

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Use models to explain how the scientific understanding of atomic structure has evolved.

PS.Chm.1.1

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger ...

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Use models to compare nuclear reactions including alpha decay, beta decay and gamma decay; nuclear fusion and nuclear fission.

PS.Chm.1.2

Atomic Orbitals

An atomic orbital represents the three-dimensional regions in an atom where an electron has the highest probability to reside. The radial distribution ...

The Pauli Exclusion Principle

The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that ...

The Energies of Atomic Orbitals

In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are ...

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and ...

electron-configuration-of-multielectron-atoms

Electron Configuration of Multielectron Atoms

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the ...

Use models to explain how electrons are distributed in atoms.

PS.Chm.1.3

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Atomic Mass

Atoms &mdash; and the protons, neutrons, and electrons that compose them &mdash; are extremely small. For example, a carbon atom weighs less than 2 ...

Molar Mass

The identity of a substance is defined not only by the types of atoms or ions it contains but by the quantity of each type of atom or ion. For example, ...

Use the Periodic Table as a model to predict the relative properties of elements based on the pattern of valence electrons in the outermost energy levels of atoms.

PS.Chm.2.1

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

Construct an explanation to infer the atomic size, reactivity, electronegativity, and ionization energy of an element based on its position in the Periodic Table.

PS.Chm.2.2

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

Lewis Structures of Molecular Compounds and Polyatomic Ions

To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:


	Determine the ...

Resonance

The Lewis structure of a nitrite anion (NO2&minus;) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...

Formal Charges

In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...

Exceptions to the Octet Rule

Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:


	...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Analyze and interpret data to explain the mechanisms and properties of the two main types of intramolecular (ionic and covalent) bonds.

Analyze the structure of atoms and isotopes.

How Bond Polarity Shapes Molecular Dipoles

Description

Transcript

More videos by Standards