Name: predicting ionic stability with lattice energy
Uploaded: 2020-09-03T13:38:28.000Z
Duration: 2 min 44 s
Channel: JoVE

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Chemistry

Matter and its Interactions

PS.Chm.3.1

The Born-Haber Cycle

يتطلب تكوين الروابط الأيونية نقل الإلكترون من معدن إلى ذرة غير فلزية وهذه العملية غالبًا ما تكون ماصة للحرارة. ومع ذلك،عند تفاعل عنصر الصوديوم والكلور،لتشكيل بلورة صلبة من كلوريد الصوديوم،تكون عملية طاردة للحرارة بشدة. لكن من أين تأتي الطاقة؟وفقًا لقانون كولوم،الكاتيونات والأنيونات تنجذب إلى بعضها البعض،بواسطة قوى إلكتروستاتيكية قوية في مصفوفة صلبة،أو شبكة.التركيبة الشبكية الناتجة تستقر عن طريق خفض الطاقة الكامنة،والتي يتم إطلاقها كحرارة،كتفاعل طارد للحرارة. إجمالي الطاقة،المرتبطة بتكوين أو تفكيك الشبكة البلورية الى مكوناتها الغازية،تسمى الطاقة الشبيكة. في مركب أيوني صلب،عدد كبير من الجسيمات المشحونة تتفاعل مع بعضها البعض،مما يجعل من الصعب،تحديد القيمة الدقيقة للطاقة الشبيكة،تجريبيا.ومع ذلك،يمكن حسابها باستخدام قانون هيس،في سلسلة من الخطوات الافتراضية،تسمى دورة بورن هابر،والتي تمثل تكوين مركب أيوني من العناصر المكونة له. على سبيل المثال،دورة بورن هاربر لتكوين كلوريد الصوديوم،تضع في الاعتبار مسارين بديلين،أحدهما مباشر والآخر غير مباشر. يمثل المسار المباشر،المحتوى الحراري القياسي لتكوين كلوريد الصوديوم،من عنصر الصوديوم والكلور.المسار غير المباشر يتكون من خمس خطوات. في الخطوة الأولى،الحالة الصلبة للصوديوم تتحول إلى شكله الغازي. بعد ذلك،جزيئات الكلور ثنائي الذرة تتفكك إلى ذرات الكلور الغازية.الخطوتان الثالثة والرابعة تفسران نقل الالكترون لتكوين أيونات. يتم إزالة الإلكترون من الصوديوم الغازي لتشكيل كاتيون الصوديوم. ثم يتم امتصاص الإلكترون بواسطة الكلور الغازي لتشكيل أنيون الكلوريد.في الخطوة الأخيرة،الجاذبية الكهروستاتيكية بين الأيونات الغازية يؤدي إلى تكوين الهيكل الشبكي. ينص قانون هيس على أن،التغيير في المحتوى الحراري الكلي عملية متدرجة،هي مجموع التغييرات في المحتوى الحراري لكل خطوة. بمعنى،قيمة المحتوى الحراري للطريق المباشر يساوي مجموع المحتوى الحراري للخطوات الخمس.من خلال حل معادلة الطاقة الشبكية،يتم تحديد قيمة سالبة كبيرة،مما يدل على تفاعل طارد للحرارة.

دورة بورن-هابر

<h4>الطاقة  الشبكية </h4><h4>الطاقة  الشبكية</h4>مركب أيوني مستقر بسبب الجاذبية الكهروستاتيكية بين أيونات موجبة وسالبة. الطاقة الشبكية لمركب هي مقياس لقوة هذا التجاذب. تُعرَّف الطاقة الشبكية (ΔHlattice) لمركب أيوني بأنها الطاقة المطلوبة لفصل مول واحد من المادة الصلبة عن أيونات الغازات المكونة له. هنا، يتم استخدام الإتفاقية حيث يتم فصل الصلب الأيوني إلى أيونات، مما يعني أن طاقات شبكية ستكون ماصة للحرارة (قيم موجبة). ثمة طريقة أخرى لاستخدام معادلة، لكن العكس، حيث تكون طاقة الشبكة طاردة للحرارة (قيم سالبة)، ويُوصف بأنها الطاقة التي يتم إطلاقها عندما تتحد الأيونات لتكوين شبكية. لذلك، تأكد من تحديد التعريف المستخدم عند البحث عن مصادر شبكية في مرجع آخر.  في كلتا الحالتين، يشير الحجم الأكبر للطاقة الشبكية إلى مركب أيوني أكثر ثباتًا. بالنسبة لكلوريد الصوديوم، تكون قيمة ΔHlattice = 769 كيلوجول. وبالتالي، يتطلب الأمر استخدام 769 كيلوجول لفصل مول واحد من NaCl الصلب إلى أيونات غازية Na+ و Cl–. عندما تتكون أيونات من أيونات غازية من نوع Na+ و Cl– من NaCl الصلب، يتم تحرير 769 كيلوجول من الحرارة. <h4>تحديد الطاقة الشبكية لمركب أيوني </h4>لا يمكن قياس طاقة شبكية مباشرة. ومع ذلك، يمكن حساب طاقة الشبكة باستخدام دورة كيميائية حرارية. إن دورة بورن-هابر عبارة عن تطبيق لقانون هس’ الذي يقطع تشكيل أيوني صلب إلى سلسلة من الخطوات الفردية: <table style="margin-left: auto; margin-right: auto;"><tbody style="border: 1px solid black;"><tr><td style="color: black; border: 1px solid black; text-align: center;">Enthalpy of sublimation of Cs (s)</td><td colspan="2" style="color: black; border: 1px solid black; text-align: center;">Cs (s) → Cs (غ)</td><td style="color: black; border: 1px solid black; text-align: center;">ΔH = ΔHs° = 76.5 كيلوجول/مول</td></tr><tr><td style="color: black; border: 1px solid black; text-align: center;">One-half of the bond energy of F2</td><td colspan="2" style="color: black; border: 1px solid black; text-align: center;">½ F2 (غ) → F (غ)</td><td style="color: black; border: 1px solid black; text-align: center;">ΔH = ½ D = 79.4 كيلوجول/مول</td></tr><tr><td style="color: black; border: 1px solid black; text-align: center;">Ionization energy of Cs (غ)</td><td colspan="2" style="color: black; border: 1px solid black; text-align: center;">Cs (غ)  → Cs+ (غ) + e−</td><td style="color: black; border: 1px solid black; text-align: center;">ΔH = IE = 375.7 كيلوجول/مول</td></tr><tr><td style="color: black; border: 1px solid black; text-align: center;">Electron affinity of F</td><td colspan="2" style="color: black; border: 1px solid black; text-align: center;">F (غ) + e− → F− (غ)</td><td style="color: black; border: 1px solid black; text-align: center;">ΔH = EA = −328.2 كيلوجول/مول</td></tr><tr><td style="color: black; border: 1px solid black; text-align: center;">Negative of the lattice energy of CsF (s)</td><td colspan="2" style="color: black; border: 1px solid black; text-align: center;">Cs+ (غ) + F− (غ) → CsF (s)</td><td style="color: black; border: 1px solid black; text-align: center;">ΔH = −ΔHlattice = ?</td></tr><tr><td style="color: black; border: 1px solid black; text-align: center;">Enthalpy of formation of CsF (s), add steps 1–5</td><td colspan="2" style="color: black; border: 1px solid black; text-align: center;">ΔH = ΔHf° = ΔHs°+ ½ D + IE + (EA) + (−ΔHlattice) Cs (s) + ½ F2 (g) → CsF (s)</td><td style="color: black; border: 1px solid black; text-align: center;">ΔH = −553.5 كيلوجول/مول</td></tr></tbody></table><ol>
 
 " <h4>الطاقة  الشبكية</h4><h4>الطاقة  الشبكية</h4><li>ضع في اعتبارك العناصر الموجودة في الحالات الأكثر شيوعًا، وهي Cs (s) و F2 (g).  </li><li>تمثل علامة ΔHs° تحويل السيزيوم الصلب إلى غاز (تسامي)، ثم تحول طاقة التأين ذرات السيزيوم الغازي إلى كاتيونات. </li><li>في الخطوة التالية، يجب حساب الطاقة المطلوبة لكسر الرابطة F–F لإنتاج ذرات الفلورين.  </li><li>تحويل مول واحد من ذرات الفلوراين إلى أيونات الفلورايد هو عملية طاردة للحرارة، لذا فإن هذه الخطوة تعطي الطاقة (انجذاب الإلكترون) </li><li>والآن هناك مول واحد من كاتيونات Cs ومول واحد من أنيونات F. تتحد هذه الأيونات لإنتاج فلوريد السيزيوم الصلب. إن التغير في المحتوى الحراري في هذه الخطوة هو التغير السالب في طاقة الشبكة، لذا فهو أيضًا كمية منتجة للحرارة.  </li><li>تساوي الطاقة الإجمالية التي ينطوي عليها هذا التحويل حرارة التكوين التي يتم تحديدها تجريبياً في تركيب ΔHf°، للمركب من عناصره. في هذه الحالة، فإن التغيير الإجمالي منتج للحرارة. </li></ol>عادة ما تكون الطاقات الشبكية محسوبة للمركبات الأيونية أعلى بكثير من طاقات فصل الروابط التي يتم قياسها للروابط التساهمية. في حين تقع الطاقات الشبكية عادة في نطاق 600– 4000 كيلو جول/مول (بعضها أعلى)، فإن طاقات فصل الروابط التساهمية تتراوح عادة بين 150 ––400 كيلو جول/مول للروابط الفردية. ومع ذلك، ضع في الاعتبار أن هذه القيم ليست قيماً قابلة للمقارنة بشكل مباشر. بالنسبة إلى المركبات الأيونية، ترتبط الطاقات الشبكية بالعديد من التفاعلات، حيث تترافق الكاتيونات والأنيونات معاً في شبكية ممتدة. بالنسبة إلى الروابط التساهمية، ترتبط طاقة فصل الروابط بتفاعل ذرتين فقط. <h4>طاقة شبكية كدالة على نصف قطر الأيون والشحنة  </h4>تزداد الطاقة الشبكية للكريستال الأيوني بسرعة مع زيادة شحن الأيونات، وانخفاض أحجام الأيونات. عندما يتم الحفاظ على ثبات جميع المعلمات الأخرى، فإن مضاعفة شحنة كل من الكاتيون والأنيون إلى أربعة أضعاف الطاقة الشبكية. على سبيل المثال، تبلغ طاقة شبكية Lif (Z+ و Z– = 1) هو 1023 كيلوجول/مول، بينما تبلغ طاقة MgO (Z+ و Z– = 2) 3900 كيلوجول/مول (Ro = المسافة بين الأيونات المعرفة بأنها مجموع نصف قطر الأيونات الموجبة والسالبة، هي نفسها تقريباً — حوالي 200 pm لكلا المركبين). تنتج المسافات بين الذرات المختلفة طاقات شبكية مختلفة. على سبيل المثال، قارن بين طاقة شبكية MgF2 (2957 كيلوجول/مول) وطاقة MgI2 (2327 كيلوجول/مول)، التي توضح التأثير على طاقة شبكية بحجم أيوني أصغر من F– مقارنة بـ I–.<h4>تطبيقات أخرى لدورة هابر المولودة </h4>كما يمكن استخدام دورة بورن-هابر لحساب أي من الكميات الأخرى في معادلة طاقة شبكية، بشرط أن يكون الباقي معروفاً. على سبيل المثال، إذا كان المحتوى الحراري ذي الصلة من للتسامي  ΔHs°، وطاقة التأين  (IE)، المحتوى الحراري لتفكك الرابطة (D)، والطاقة الشبكية ΔHlattice، والمحتوى الحراري القياسي للتكوين  ΔHf°،  هي معروفة، يمكن استخدام دورة بورن-هابر لتحديد انجذاب الإلكترون للذرة. هذا النص مقتبس من <a href="https://openstax.org/books/chemistry-2e/pages/7-5-strengths-of-ionic-and-covalent-bonds">Openstax, Chemistry 2e, Section 7.5: Strengths of Ionic and Covalent Bonds.</a>

الطاقة الشبكية

المركب الأيوني مستقر بسبب التجاذب الكهروستاتيكي بين الأيونات الموجبة والسالبة. الطاقة الشبكية ل ...

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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 case, a larger lattice energy magnitude means a more stable ionic compound.

Sodium chloride gives a simple example. Its lattice energy is 769 kJ/mol, which means 769 kJ is needed to pull one mole of solid NaCl apart into Na+ and Cl- ions in the gas phase. The same amount of heat is released when those ions come together to form solid NaCl. This value shows how strongly the ions attract each other in the crystal.

Lattice energy cannot be measured directly. Instead, it is found with a thermochemical cycle. The Born-Haber cycle uses Hess’s law to break the formation of an ionic solid into separate steps. For cesium fluoride, these steps include sublimation of Cs(s) to Cs(g), half of the F2 bond energy to make F(g), ionization of Cs(g) to Cs+(g) plus an electron, electron affinity of F(g) to make F-(g), and formation of solid CsF from the gaseous ions. The enthalpy change for forming the lattice is the negative of the lattice energy.

For CsF, the overall reaction Cs(s) + 1/2 F2(g) -&gt; CsF(s) has a standard enthalpy of formation of -553.5 kJ/mol. The cycle combines the sublimation enthalpy of cesium, 76.5 kJ/mol, one-half of the F2 bond energy, 79.4 kJ/mol, the ionization energy of cesium, 375.7 kJ/mol, and the electron affinity of fluorine, -328.2 kJ/mol, with the lattice term. Because the total is exothermic, energy is released overall when the solid forms from the elements in their most common states, Cs(s) and F2(g).

Lattice energies for ionic compounds are usually much larger than bond dissociation energies for covalent bonds. Ionic lattice energies often fall between 600 and 4000 kJ/mol, and some are even higher. Single covalent bond dissociation energies are usually about 150 to 400 kJ/mol. These values are not directly comparable because lattice energy reflects many attractions in an extended crystal, while a covalent bond energy describes the interaction of just two atoms.

Ion charge and ion size strongly affect lattice energy. When all other factors stay the same, larger charges give much larger lattice energies, and smaller ions also increase lattice energy. Doubling the charge on both ions can quadruple the lattice energy. For example, LiF has a lattice energy of 1023 kJ/mol, while MgO is 3900 kJ/mol, even though their interionic distances are nearly the same at about 200 pm. Size also matters in compounds such as MgF2 and MgI2, where the smaller F- ion leads to a higher lattice energy than the larger I- ion.

The Born-Haber cycle can also solve for other unknowns in the lattice energy equation. If the other terms are known, the cycle can be used to find a missing quantity such as electron affinity. This makes the method useful for linking measured enthalpy values to the energy changes inside ionic compounds.

Predicting Ionic Stability with Lattice Energy

predicting-ionic-stability-with-lattice-energy

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

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

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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

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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...

lewis structures of molecular compounds and polyatomic ions

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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 lattice energy, ion charge, ion size, and the Born-Haber cycle help explain ionic stability and calculate values for compounds like CsF.

Predicting Ionic Stability with Lattice Energy | JoVE K12

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Bonding Types: From Nonpolar Covalent to Ionic

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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 ...

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, Dipole Moment, and Percent Ionic Character

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.

Predicting Ionic Stability with Lattice Energy

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