Name: ionic compounds and crystal lattices
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

North Carolina K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.3.1

Ionic Bonding and Electron Transfer

离子键是由电子从金属转移到 非金属而形成的。与电子被共享的共价键相比，在离子键中，金属倾向于丢失电子，而非金属 则倾向于接受电子 但这是为什么呢？一个原子的最稳定的电子构型 是具有一个全八位态。达到这种状态 同时降低势能 是键形成的主要驱动力。但是如何预测电子何时 会转移而不是共享呢？对于这个问题，可以检查一下原子的电离能 和电子亲和力。在周期表上，s 区的金属元素 具有较低的电离能。这有助于在同时形成阳离子时，更容易失去电子达到八位态。相反地，来自 p 区的非金属元素，除了惰性气体，具有很高的电子亲和力，并且很容易接受电子形成阴离子。带相反电荷的阳离子和阴离子会发生 强烈的静电相互作用，相互吸引 而形成离子键。由于离子间强烈的静电吸引，离子化合物通常会形成具有高熔点的 坚硬而清晰的晶体结构。以氟化锂为例，一种由锂和氟 组成的离子化合物。当锂失去一个电子而变成一个 呈二位态的锂阳离子时，电子 被氟吸收，形成一个具有八位态的阴离子。根据库仑定律，这两个 带电粒子相互吸引，形成 一种中性化合物氟化锂。路易斯模型可以用来描述和预测 离子化合物的化学式。路易斯符号在右上角显示电荷，并用括号内的符号表示阴离子 和阳离子。以氯化锶为例，它是一种常用的盐，可以在烟花中获得鲜艳的红色。锶的路易斯符号有两个未成对电子，而氯的路易斯符号有一个未成对电子。锶必须失去两个电子，而氯必须获得一个电子才能到达八位态。因此，一个锶离子会与两个氯离子 以 1:2 的比例结合。

离子键和电子转移

离子是带有电荷的原子或分子。当中性原子从其化合价壳中失去一个或多个电子时，会形成阳离子（正离子），而当中性原子在其化合价壳中获得一个或多个电子时，会形成阴离子（负离子）。由离子组成的化合物称为离子化合物（或盐），其组成离子通过离子键结合在一起：带相反电荷的阳离子和阴离子之间的静电吸引力。
 
 <h4>离子化合物的性质</ h4>
 
 离子化合物的性质为离子键的性质提供了一些启示。
 
 <ul>
 离子固体表现出晶体结构，并且倾向于是刚性和脆性的。它们也往往具有较高的熔点和沸点，这表明离子键非常牢固。</ li>
 出于同样的原因，离子固体也是电的不良导体＆mdash;离子键的强度会阻止离子在固态中自由移动。</ li>
 但是，大多数离子型固体很容易溶于水。离子化合物一旦溶解或熔化，便是电和热的极好导体，因为离子可以自由移动。</ li>
 </ ul>
 
 <h4>离子化合物的形成</ h4>
 
 许多金属元素的电离势较低，并且容易失去电子。这些元素位于周期表中某个周期的左侧或底部附近。非金属原子具有相对较高的电子亲和力，因此很容易获得由金属原子损失的电子，从而填充了它们的化合价壳。非金属元素位于元素周期表的右上角。
 
 由于所有物质必须是电中性的，因此离子化合物阳离子上的正电荷总数必须等于其阴离子上的负电荷总数。离子化合物的分子式表示给出相同数量的正负电荷所需的最简单的离子数量比。
 
 <h4>离子化合物形成规则排列的三维结构</ h4>
 
 但是，重要的是要注意，离子化合物的化学式并不代表其离子的物理排列。提到氯化钠（NaCl）“分子”是不正确的。因为在任何特定的钠离子和氯离子对之间本身没有单个离子键。离子之间的吸引力是各向同性的-各个方向都一样意味着任何特定的离子都被附近所有带相反电荷的离子均吸引。这导致离子将它们自己排列成紧密结合的三维晶格结构。例如，氯化钠由相等数目的Na + 阳离子和Cl n 阴离子组成的规则排列组成。 Na + 和Cl n 离子之间的强静电吸引力使它们在固体NaCl中紧密结合在一起。将一摩尔固体NaCl分解成单独的气态Na + 和Cl 离子需要769 kJ的能量。
 
 <h4>阳离子的电子结构</ h4>
 
 形成阳离子时，主族元素的原子趋于失去其所有价电子，因此假定其在周期表中位于其之前的稀有气体的电子结构。
 
 <ul>
 <li>对于第1组（碱金属）和第2组（碱土金属），组数等于价壳电子的数目，因此等于这些元素的原子所形成的阳离子的电荷。价壳电子被去除。</ li>
 <li>例如，钙是2族元素，其中性原子具有20个电子，基态电子构型为1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 。当Ca原子失去两个价电子时，结果是阳离子带有18个电子，2 +电荷和1 s 2 2 <em的电子构型> s 2 2 p 6 3 s 2 3 p 6 。因此，Ca 2 + 离子与稀有气体Ar等电子。</ li>
 <li>对于第13至17组，组数比价电子数高10个（这说明在第四和更大周期中元素的原子中完整的 d 子壳的可能性）。因此，由所有价电子的损失形成的阳离子的电荷等于基团数减去10。例如，铝（第13组）形成3+离子（Al 3 + ）。 </ li>
 </ ul>
 
 <h4>例外</ h4>
 
 <ul>
 <li>预期行为的例外情况涉及到组底部的元素。</ li>
 <li>除了预期离子Tl 3 + ，Sn 4 + ，Pb 4 + 和Bi 5+ ，这些原子会部分丢失＆rsquo;价壳电子还可导致Tl + ，Sn 2 + ，Pb 2 + 和Bi 3+ 离子。这些1 +，2 +和3+阳离子的形成归因于惰性对效应，这反映了基团重元素原子的价 s -电子对相对较低的能量13、14和15。</ n>
 <li>汞（第12组）还表现出出乎意料的行为：它形成双原子离子Hg 2 2 + （由两个汞原子形成的离子，带有一个Hg -Hg键），以及预期的单原子离子Hg 2 + （仅由一个汞原子形成）。</ li>
 <li>过渡金属元素和内部过渡金属元素的行为与主要族元素不同。大多数过渡金属阳离子具有2+或3+电荷，这些电荷首先是由于其最外面的 s 电子损失而引起的，有时随后是一或两个 d 的损失来自最接近外壳的电子。</ li>
 尽管过渡元素的d轨道是按照构造原理的，但在建立电子构型时最后一个要填充，但最外层的电子在这些原子电离时最先丢失。当内部过渡金属形成离子时，它们最外面的s电子和d或f电子的损失通常会带3+电荷。</ li>
 </ ul>
 
 <h4>阴离子的电子结构</ h4>
 
 当中性非金属原子获得足够的电子以完全填充其外部 s 和 p 轨道时，形成大多数单原子阴离子，从而达到下一个稀有气体的电子构型。因此，很容易确定这种负离子上的电荷：该电荷等于填充π的 s 和 p 轨道必须获得的电子数。父原子。例如，氧气的电子构型为1 s 2 2 s 2 2 p 4 ，而氧负离子具有稀有气体氖（Ne）的电子构型，即1 s 2 2 s 2 2 p 6 。填充化合价轨道所需的另外两个电子为氧化物离子提供2的电荷。 （O 2＆ndash; ）。
 
 本文改编自<a href="https://openstax.org/books/chemistry-2e/pages/7-1-ionic-bonding"> Openstax，化学2e，第7.3节：离子键合。</a>

离子是带有电荷的原子或分子。当一个中性原子从其价电子层失去一个或多个电子时，便形成阳离子（正离子）。

Education

教育

JoVE Core

化学

Chemical Bonding: Basic Concepts

化学键：基本概念

KEY TERMS AND CONCEPTS

关键术语与概念

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 melting and boiling points. They are also poor conductors of electricity in the solid state because the ions cannot move freely. Most ionic solids dissolve readily in water. When an ionic compound is melted or dissolved, it conducts electricity and heat well because the ions can move about freely.

Ionic compounds form most easily when metals lose electrons and nonmetals gain them. Many metals have low ionization potentials, so they lose electrons easily. These elements are found on the left side of the periodic table or near the bottom of a group. Nonmetals have high electron affinities, so they readily gain the electrons lost by metals. They are found in the upper-right corner of the periodic table.

Ionic compounds must remain electrically neutral. That means the total positive charge from the cations must equal the total negative charge from the anions. The formula of an ionic compound gives the simplest ratio of ions needed to balance charge. The formula does not show the physical layout of the ions. In solid sodium chloride, for example, the ions form a tightly bound three-dimensional lattice. The attraction between Na+ and Cl- ions is strong, and it takes 769 kJ of energy to separate one mole of solid NaCl into gaseous ions.

Main-group cations often form by losing all valence electrons and taking on the electron structure of the noble gas before them. For groups 1 and 2, the group number matches the number of valence electrons and also the charge of the ion formed. Calcium is a group 2 element. A neutral calcium atom has 20 electrons, and Ca2+ has 18 electrons with the same electron configuration as argon. For groups 13 through 17, the cation charge equals the group number minus 10. Aluminum, in group 13, forms Al3+.

Some heavy main-group elements do not follow the expected pattern exactly. Thallium, tin, lead, and bismuth can also form lower-charge ions such as Tl+, Sn2+, Pb2+, and Bi3+. This is explained by the inert pair effect, which reflects the relatively low energy of the valence s-electron pair in these heavy atoms. Mercury is another exception. It can form the diatomic ion Hg2^2+, which contains a Hg-Hg bond, as well as the monatomic ion Hg2+.

Transition metals and inner transition metals form ions in a different way. Most transition metal cations have 2+ or 3+ charges. These usually come from losing the outermost s electron or electrons first, and sometimes one or two d electrons after that. Even though d orbitals fill later according to the Aufbau principle, the outermost s electrons are lost first when transition metals ionize. Inner transition metals usually form 3+ ions by losing their outermost s electrons and one d or f electron.

Most monatomic anions form when a nonmetal atom gains enough electrons to fill its outer s and p orbitals. The charge on the ion equals the number of electrons needed to reach the next noble-gas electron configuration. Oxygen is a clear example. A neutral oxygen atom has the configuration 1s2 2s2 2p4. The oxide ion, O2-, has the neon configuration, 1s2 2s2 2p6, after gaining two electrons.

Ionic Compounds and Crystal Lattices

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 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

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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

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

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bonding in metals

Electron Sea Model in Metals

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key terms and concepts

Explore how ions form, why ionic compounds make crystal lattices, and how charge, conductivity, and electron configurations shape ionic behavior in chemistry.

Ionic Compounds and Crystal Lattices | JoVE K12

chemistry

JoVE Core 化学通过简单明了且通俗易懂的动画视频课程，将普通化学概念带入到现实生活当中。此外，在科学家行动视频中，我们演示了在实验室中进行的经典和原始研究实验。

Physical Science

PS.PSc.2.1

Pennsylvania State Academic Standards

Structure and Properties of Matter

3.2.9-12.B

3.2.9-12.N

Louisiana Student Standards for Science

High School

Matter And Its Interactions

HS-PS1-3

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Bonding and compounds

Structure And Properties Of Matter

Chemical bonding

Physical Geology

Minerals

Chemical bonding (ionic, covalent, metallic)

Tennessee Academic Standards

Matter and Its Interactions

CHEM1.PS1.13

CHEM1.PS1.14

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

CHEM1.PS2.1

Virginia  Standards of Learning

HIgh School

CH.3

CH.3.d

PS.3

PS.3.c

Physics

PH.9

PH.9.e

Minnesota Academic Standards in Science

1.2.1 9L.4.2.2.1

Arizona Science Standards

HS.P1

HS.P1U1.2

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

HS-PS1-2

Alabama Course of Study Science

9-12.C.2.2.b

Florida Department of Education

SC.912.P.8

SC.912.P.8.6

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.

Georgia Standards of Excellence

SPS2.

Chemical Bonds

SC2.

bonding-types-from-nonpolar-covalent-to-ionic

Bonding Types: From Nonpolar Covalent to Ionic

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 ...

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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

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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 ...

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

Analyze the structure of atoms and isotopes.

Ionic Compounds and Crystal Lattices

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