Name: halogens: trends and reactions
Uploaded: 2020-09-03T13:38:28.000Z
Duration: 3 min 1 s
Channel: JoVE

K12 Standards

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

NC K-12 Science Standard Course of Study

9-12

Physical Science

Matter and its Interactions

PS.PSc.1.6

Halogens

卤素是五个非金属元素的集合-氟，氯，溴，碘和a-属于第 17组。元素卤素以双原子分子形式存在。在室温下，氟和氯为气体，溴为液体，碘为固体。对第五元素a的性质了解甚少，a是一种稀有的高 放射性固体。卤素的物理性质（例如元素颜色）随着在基团中的移动而变化。原子半径随着原子序数的增加而增加，熔点和沸点从氟到 碘呈上升趋势。相反，周期性性质如电负性，反应性和电子亲和力 会降低基团。卤素的电子构型表明它们具 有七个价电子，距离其最近的稀有气 体构型还差一个电子。因此，卤素具有较高的电负性，并且具有获得一个额外的电子以完成 其八位位组的强烈趋势，与其他基团相比，它们具有较高的反应活性和强大的氧化剂。在卤素和碘中，氟是最有效的氧化剂。卤素还表现出很高的负电子亲和力，这是中性原子获得电 子时能量的变化。它以每摩尔千焦耳表示，负值表示反应的 放热性质。卤素与大多数金属反应生成金属卤化物。例如，氯和钠反应生成氯化钠，这是一种离子化合物。卤素与氢反应形成极性共价化合物，称为卤化氢，通常溶解于水中形成氢卤酸。卤素还会与水反应。氟与水的反应高度放热，产生氟化氢（一种强酸）和氧气。但是，氯的反应较慢，会生成盐酸和次 氯酸（一种强氧化剂）此外，卤素可以相互反应，生成称为卤素间化合物的二元共价化合物。例如，溴与氟反 应形成三氟化溴。

卤素

第17类元素（称为卤素）是非金属。在室温下，氟和氯为气体，溴为液体，碘为固体。是一种高度不稳定的放射性元素，因此目前，由于其半衰期短，其大部分特性尚不得而知。田纳西汀是一种合成元素，也预计会出现在这一组中。
 
 没有发现卤素是单原子，而是作为双原子分子存在。原子半径从氟增加到碘。卤素的价壳电子构型为 ns 2 np 5 ，并且它们倾向于接受电子实现稀有气体的配置。表1列出了卤素的各种特性。
 
 表1：卤素的性质。
 
 <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;">元素</td>
 <td style="color: black; border: 1px solid black; text-align: center;">电子配置</td>
 <td style="color: black; border: 1px solid black; text-align: center;">原子半径(pm)</td>
 <td style="color: black; border: 1px solid black; text-align: center;">IE1 (kJ/mol)</td>
 <td style="color: black; border: 1px solid black; text-align: center;">EA (kJ/mol)</td>
 <td style="color: black; border: 1px solid black; text-align: center;">在25摄氏度下的密度</td>
 <td style="color: black; border: 1px solid black; text-align: center;">熔点 (°C)</td>
 </tr>
 <tr>
 <td style="color: black; border: 1px solid black; text-align: center;">F</td>
 <td style="color: black; border: 1px solid black; text-align: center;">[He] 2s22p5</td>
 <td style="color: black; border: 1px solid black; text-align: center;">71</td>
 <td style="color: black; border: 1px solid black; text-align: center;">1680</td>
 <td style="color: black; border: 1px solid black; text-align: center;">-328</td>
 <td style="color: black; border: 1px solid black; text-align: center;">1.70 g/L</td>
 <td style="color: black; border: 1px solid black; text-align: center;">-219</td>
 </tr>
 <tr>
 <td style="color: black; border: 1px solid black; text-align: center;">Cl</td>
 <td style="color: black; border: 1px solid black; text-align: center;">[Ne] 3s23p5</td>
 <td style="color: black; border: 1px solid black; text-align: center;">99</td>
 <td style="color: black; border: 1px solid black; text-align: center;">1250</td>
 <td style="color: black; border: 1px solid black; text-align: center;">-348</td>
 <td style="color: black; border: 1px solid black; text-align: center;">3.12 g/L</td>
 <td style="color: black; border: 1px solid black; text-align: center;">-101</td>
 </tr>
 <tr>
 <td style="color: black; border: 1px solid black; text-align: center;">Br</td>
 <td style="color: black; border: 1px solid black; text-align: center;">[Ar] 4s24p5</td>
 <td style="color: black; border: 1px solid black; text-align: center;">114</td>
 <td style="color: black; border: 1px solid black; text-align: center;">1140</td>
 <td style="color: black; border: 1px solid black; text-align: center;">-324</td>
 <td style="color: black; border: 1px solid black; text-align: center;">3.19 g/cm3</td>
 <td style="color: black; border: 1px solid black; text-align: center;">-7</td>
 </tr>
 <tr>
 <td style="color: black; border: 1px solid black; text-align: center;">I</td>
 <td style="color: black; border: 1px solid black; text-align: center;">[Kr] 5s25p5</td>
 <td style="color: black; border: 1px solid black; text-align: center;">133</td>
 <td style="color: black; border: 1px solid black; text-align: center;">1010</td>
 <td style="color: black; border: 1px solid black; text-align: center;">-295</td>
 <td style="color: black; border: 1px solid black; text-align: center;">3.96 g/cm3</td>
 <td style="color: black; border: 1px solid black; text-align: center;">114</td>
 </tr>
 </tbody>
 </table>
 
 卤素的电子亲和力具有较大的负值；因此，卤素是强氧化剂。氟是具有最大负电子亲和力的最强氧化剂。卤素与金属反应以获得电子并产生相应的金属卤化物。例如，氯与铁反应生成氯化铁，与钠反应生成氯化钠。卤素与氢反应形成卤化氢，将其溶于水中以生成氢卤酸。氢氟酸是最弱的卤代酸。氟与水剧烈反应。反应高度放热并产生氧气。氯与水的反应较不剧烈。该反应产生的次氯酸是一种强氧化剂。
 
 卤素彼此反应形成卤素间化合物，其中许多是二元化合物。 卤素间化合物的一般分子式为AB n ，其中A为原子数较高的卤素，为奇数。 卤素间化合物的几个例子是ICl，IBr，BrF，BrCl，ClF。 卤素与碳反应形成商业上重要的化合物。 ＆nbsp;例如，乙烯与氟反应生成全氟乙烯。
 
 本文改编自<a href="https://openstax.org/books/chemistry-2e/pages/6-5-periodic-variations-in-element-properties"> Openstax，化学 2e，第6.5节：元素属性的周期性变化。</a>

第17族元素，称为卤素，属于非金属。在室温下，氟和氯为气体，溴为液体，碘为固体。

Education

教育

JoVE Core

Chemistry

化学

Periodic Properties of the Elements

元素的周期性质

KEY TERMS AND CONCEPTS

关键术语与概念

halogens: trends and reactions

Halogens are Group 17 nonmetals that show clear trends in structure and reactivity. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid. Astatine is highly unstable and radioactive, so most of its properties are still unknown because it has a very short half-life. Tennessine is a synthetic element that is also predicted to belong to this group.

These elements do not usually exist as single atoms. Instead, they form diatomic molecules, which means each molecule has two atoms. Their atomic radius increases from fluorine to iodine, and their outer-shell electron pattern is ns2 np5. This electron arrangement helps explain why halogens tend to gain one electron and reach a noble gas configuration.

The table of halogen properties shows important changes across the group. Fluorine has the smallest atomic radius, while iodine has the largest. First ionization energy decreases from fluorine to iodine, and electron affinity stays strongly negative for the group. Because of this, halogens are powerful oxidizing agents, and fluorine is the strongest oxidizing agent in the group.

Halogens react with metals to form metal halides. For example, chlorine reacts with iron to make iron chloride, and it reacts with sodium to make sodium chloride. They also react with hydrogen to form hydrogen halides. When these dissolve in water, they produce hydrohalic acids, and hydrofluoric acid is the weakest haloacid.

Halogens also react with water, but not in the same way. Fluorine reacts very vigorously, and the reaction is highly exothermic, which means it releases a large amount of heat. It also produces oxygen. Chlorine reacts less vigorously with water, and the hypochlorous acid formed is a strong oxidizing agent.

Halogens can react with one another to form interhalogen compounds, which are often binary compounds. Their general formula is ABn, where A is the halogen with the higher atomic number and n is an odd number. Examples include ICl, IBr, BrF, BrCl, and ClF. Halogens also react with carbon to form useful compounds, such as perfluoroethylene from the reaction of ethylene with fluorine.

Halogens: Trends and Reactions

periodic classification of the elements

How Valence Electrons Shape the Periodic Table

The periodic table organizes elements by increasing atomic number, and it also shows why elements in the same group behave alike. As the electron configurations are placed into the table, a repeating pattern appears in the outer shells of atoms. These outer electrons are called valence electrons, and they play the biggest role in chemical reactions. They are the highest-energy electrons in an atom, so they are easier to lose or share than core electrons. Valence electrons also help determine...

ionization energy

Ionization Energy Trends in the Periodic Table

Ionization energy is the energy needed to remove an electron from a gaseous atom or ion in its ground state. The first ionization energy, or IE1, removes the most loosely bound electron and forms a 1+ cation. The second ionization energy, IE2, removes the next electron, and each later ionization energy removes another electron from the atom or ion. Ionization always requires energy, so these processes are endothermic. That means ionization energy values are always positive. In general, larger...

atomic radii and effective nuclear charge

atomic-radii-and-effective-nuclear-charge

Periodic Trends in Atomic Size

Periodic trends in atomic size help explain why atoms get larger or smaller across the periodic table. Elements in the same group show similar chemical behavior because they have the same number and arrangement of valence electrons. Across a period, each new element adds one proton to the nucleus and one electron to the valence shell. Down a group, the number of valence electrons stays the same, but the principal quantum number increases by one. Atomic radius is not easy to define with perfect...

ionic radii

How Ionic Charge Changes Ion Size

Ionic radius describes the size of an ion. It changes when an atom gains or loses electrons. Cations are positive ions with fewer electrons than the parent atom, and they are smaller than the atoms they come from. Aluminum shows this pattern clearly. A neutral aluminum atom has a covalent radius of 118 pm, while Al3+ has an ionic radius of 68 pm. When electrons are removed from the outer valence shell, the remaining core electrons feel a stronger effective nuclear charge, or Zeff. That pull...

electron affinity

Electron Affinity Trends on the Periodic Table

Electron affinity is the energy change that happens when a gaseous atom gains an electron and becomes a negative ion, or anion. For many elements, this process releases energy, so the electron affinity value is negative. For some elements, energy must be added instead, so the value is positive. Electron affinity also applies when more than one electron is added. The second electron affinity is the energy change for adding an electron to an anion to make a 2− ion. Later electron affinities...

alkali metals

Alkali Metals: Reactivity Trends

Alkali metals are Group 1 elements with one valence electron. They are soft, shiny metallic solids that are malleable, ductile, and good conductors of heat and electricity. Their melting points are unusually low for metals and drop as you move down the group. Density generally increases down the group, except for potassium. The trend in atomic size helps explain their behavior. Moving from lithium to cesium, each element has a higher principal quantum number, so the outer electron is farther...

halogens

Halogens are Group 17 nonmetals that show clear trends in structure and reactivity. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid. Astatine is highly unstable and radioactive, so most of its properties are still unknown because it has a very short half-life. Tennessine is a synthetic element that is also predicted to belong to this group. These elements do not usually exist as single atoms. Instead, they form diatomic molecules, which means...

noble gases

Noble Gases: Sources, Uses, and Reactions

Noble gases are the group 18 elements helium, neon, argon, krypton, xenon, and radon. They were called “noble” because they were once thought to be nonreactive. That idea changed in 1962, when Dr. Neil Bartlett at the University of British Columbia showed that this assumption was not fully correct. These gases occur in very small amounts in the atmosphere. Some natural gas contains 1–2% helium by mass. Helium is separated from natural gas by removing the condensable components, which leaves...

key terms and concepts

Explore halogen trends, from physical states and electron configuration to oxidizing strength, metal halides, hydrohalic acids, and interhalogen compounds.

Halogens: Trends and Reactions | 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。

Pennsylvania State Academic Standards

Chemical Reactions

3.2.9-12.C

Structure and Properties of Matter

3.2.9-12.A

Louisiana Student Standards for Science

High School

Matter And Its Interactions

HS-PS1-1

HS-PS1-2

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Periodic trends of the elements

Structure And Properties Of Matter

Periodic Table

Tennessee Academic Standards

Matter and Its Interactions

CHEM1.PS1.12

Virginia  Standards of Learning

HIgh School

PS.2

PS.2.b

PS.4

PS.4.b

Arizona Science Standards

HS.P1

HS.P1U1.1

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

New Jersey Student Learning Standards for Science

Texas Essential Knowledge and Skills

CHEM.5

CHEM.5.B

Alabama Course of Study Science

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

9-12.C.2.2.f

9-12.PS.3.4.b

Next Generation Science Standards

Chemistry and Physics

IPC.7

IPC.7.B

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-2.

Georgia Standards of Excellence

SPS1.

Periodic Table Trends

SC1.

electron-configuration-and-chemical-properties

Electron Configuration and Chemical Properties

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 ...

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 ...

Molecules and Compounds

Atoms and Molecules

Everything in the universe is made up of matter, and matter is composed of a combination of elements. An atom is the smallest unit of ...

Solution Formation

There is no one solvent that can dissolve every type of solute. Some substances that readily dissolve in a certain solvent might be insoluble in a ...

Colloids

Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera ...

Construct an explanation to classify matter as a pure substance or mixture; homogeneous or heterogeneous; element or compound; solution, colloid or suspension.

PS.PSc.1.1

Phase Transitions

Whether solid, liquid, or gas, a substance&#39;s state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the ...

phase-transitions-vaporization-and-condensation

Phase Transitions: Vaporization and Condensation

The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize ...

Vapor Pressure

When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules move randomly about, they will occasionally ...

Clausius-Clapeyron Equation

The equilibrium between a liquid and its vapor depends on the temperature of the system; a rise in temperature causes a corresponding rise in the vapor ...

Phase Transitions: Melting and Freezing

Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy ...

phase-transitions-sublimation-and-deposition

Phase Transitions: Sublimation and Deposition

Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and ...

Heating and Cooling Curves

When a substance&#8212;isolated from its environment&#8212;is subjected to heat changes, corresponding changes in temperature and phase of the substance ...

Phase Diagrams

A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. ...

Use models to compare the phases of matter and the physical changes they undergo.

PS.PSc.1.2

physical-and-chemical-properties-of-matter

Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

molecular-comparison-of-gases-liquids-and-solids

Molecular Comparison of Gases, Liquids, and Solids

Particles in a solid are tightly packed together (fixed shape) and often arranged in a regular pattern; in a liquid, they are close together with no ...

Intermolecular vs Intramolecular Forces

Intermolecular forces (IMF) are electrostatic attractions arising from charge-charge interactions between molecules. The strength of the intermolecular ...

Intermolecular Forces

Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions ...

comparing-intermolecular-forces-melting-point-boiling-point

Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility

Intermolecular forces are attractive forces that exist between molecules. They dictate several bulk properties, such as melting points, boiling points, ...

Carry out investigations to compare physical and chemical properties of matter.

PS.PSc.1.3

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 ...

The Bohr Model

Following the work of Ernest Rutherford and his colleagues in the early twentieth century, the picture of atoms consisting of tiny dense nuclei surrounded ...

Emission Spectra

When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a ...

The de Broglie Wavelength

In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a ...

The Uncertainty Principle

Werner Heisenberg considered the limits of how accurately one can measure properties of an electron or other microscopic particles. He determined that ...

Use models to interpret the data presented in Bohr diagrams and electron dot diagrams for neutral atoms of elements 1 through 18.

PS.PSc.1.4

Ions and Ionic Charges

In ordinary chemical reactions, the nucleus &mdash; which contains the protons and neutrons of each atom and thus identifies the element &mdash; remains ...

Use models to compare representations of atoms, ions, and isotopes.

PS.PSc.1.5

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 ...

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 ...

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 ...

Alkali Metals

Group 1 elements are soft and shiny metallic solids. They are malleable, ductile, and good conductors of heat and electricity. The melting points of the ...

Group 17 elements, known as halogens, are nonmetals. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine a solid. ...

Noble Gases


The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name &ldquo;noble&rdquo; because they were ...

Use the Periodic Table as a model to predict the relative properties (metallic/nonmetallic character, ionic charge, and reactivity) and arrangement of elements based on the pattern of valence electrons in the outermost energy levels of atoms.

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 ...

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 ...

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 ...

Bonding in Metals

Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Dr&#xFC;de called the ...

Construct an explanation to classify the type of chemical bond that occurs (covalent, ionic, or metallic) in a given substance.

PS.PSc.2.1

Nomenclature of Alkanes

In the late 19th-century, the number of new chemical compounds discovered increased tremendously. Hence, the necessity arose to develop a naming system ...

Use models to apply International Union of Pure and Applied Chemistry (IUPAC) conventions to name and write formulas for simple compounds.

PS.PSc.2.2

Understand types, properties, and structure of matter.

Halogens: Trends and Reactions

Description

Transcript

Tags

More videos by Standards