Name: how valence electrons shape the periodic table
Uploaded: 2020-09-03T13:38:28.000Z
Duration: 4 min
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.2.1

Periodic Classification of the Elements

佔据原子最外壳层的是价电子，而当电子 佔据内部主要能源处时，其为核心电子。电子构型为［Ne]3s1的钠原子具有 三个主要能源级别。2s22p6的内部完整主要能源级别 表示其接续着第三外层含有的剩馀一个电子，有十个核心电子。因此，钠具有一个假电子。同样地，氯有十个核心电子 和七个价电子。价电子距离原子核最远 并最松散的连结着。因此，它们是最容易失去或共享或 在化学键合中起到重要作用的。具有相同价电子数的元素 表现相似的化学性质，从现代元素周期表的排 列上可以看出。以主组元素来说，组的序号 等同于价电子数 而行列的编号等同于该元素最高主 量子的编号。组中的每个元素具有相同数量的电子 其可用于连结。向下的群组，主量子数 依序增加一，而价电子数保持不变。元素周期表的最左侧两列 构成S区块。对于这些元素，最后一个电子进入s轨道。除了氢以外的第一组元素 被称为硷金属，并且因为它们只有一个价电子，极易产生反应。第二族元素是硷土金属 在化合价壳中有两个电子。六个最右边的一列形成p区块。这些元素的价壳 完全地佔据了s轨道 而最后一个电子进入p轨道。从3A到8A，p轨道中的电子数增加一。稀有气体具有八个价电子 除了属于S区块并且只有两个 价电子的氦之外。d区块由s和p之间的十 个行列所组成。这些元素被称为过度金属。在主外壳程序中最后一个进入d 轨道的电子其行数比行号少一。第四行中，轨道行数为3，第五行中，为4，以此类推。内部过渡元素构成f区块 其最后一个电子进入f轨道。f轨道的主量子数 每行填充的行数比行号少2。第六行中，充斥4个f轨道，而第七行中五个。镧系和锕类中编排 内部过渡元素，每块中的列数 表示在每区块的子级别中 可以填充多少个电子。s区块中的两列和在p 区块中具有两个电子、六列的s轨道互相关联，其在p区块中代表三个带有六个电子的P轨道。而区块d中的十列对应于五 个各有两个电子的轨道。最后，f区块包含十四列 表示七个f轨道的最大容量。

元素的周期分类

元素周期表根据原子序数的增加排列原子，从而使具有相同化学性质的元素周期性地重复出现。当将其电子构型添加到表中时，会观察到这些元素的外壳中类似电子构型的周期性重复出现。由于价电子在原子的外壳中，因此它们在化学反应中起着最重要的作用。外部电子具有原子中电子的最高能量，比核心电子更容易丢失或共享。价电子也是元素某些物理性质的决定因素。
 
 水平行称为句点。在整个周期中，每个连续的元素在原子核中都有一个附加的质子，并且在价态壳中具有一个附加的电子。垂直列是组。任何一组（或一列）中的元素具有相同数量的价电子（图1）；碱金属的锂和钠仅具有一个价电子，碱土金属的铍和镁均具有两个价电子，卤素的氟和氯分别具有七个价电子。价电子的损失，获得或共享决定了元素的反应方式。同一族元素之间的化学性质相似，是因为它们具有相同数量的价电子。
 
 重要的是要记住，周期表是在元素的原子结构尚未得到任何了解之前就根据元素的化学行为而开发的。现在可以理解元素周期表的排列；原子中具有相同价电子数量的元素在同一组中。图1的彩色部分显示了按填充的轨道分类的三类元素。
 
 <img alt =“ Eq1” src =“ https://www.jove.com/files/core/CDNSource/lessons/1046/1046Image_1v2.png” /> 
 图1：此版本的周期表显示了每个元素的配置。请注意，在每个组中，配置通常是相似的。
 
 主要组元素有时称为代表元素。这些元素是最后添加的电子进入最外层外壳中的 s 或 p 轨道的元素，在图1中以蓝色和红色显示。该类别包括所有非金属元素，以及准金属和许多金属。主族元素的价电子是 n 能级最高的那些。例如，镓（Ga，原子序数为31）具有电子构型[Ar] 4 s 2 3 d 10 4 p 1 ，其中包含三个价电子（带下划线）。完全填充的 d 轨道算作核心电子，而不是价电子。
 
 两个最左列构成 s 块，六个最右列构成 p 块。稀有气体是 p 嵌段的一部分，除了氦气中有两个电子外，它们都具有八个价电子。这些元素高度稳定且无反应。
 
 过渡元素或过渡金属：这些是最后添加的电子进入 d 轨道的金属元素。这些元素中的价电子（在最后一种惰性气体构型后添加的价电子）包括 ns 和（ n ＆ndash; 1） d 电子。 IUPAC对过渡元素的正式定义指定了部分填充了 d 轨道的元素。因此，具有完全填充的轨道的元素（图1中的Zn，Cd，Hg以及Cu，Ag和Au）在技术上不是过渡元素。但是，该术语经常用于指代整个 d 块（图1中为黄色）。
 
 d 块由10列组成。填满每一行的 d 轨道的主要量子数等于行数减一。在第四行中，填充3 d 个轨道，在第五行中，填充4 d 个轨道，依此类推。
 
 内部过渡元素：它们在图1中以绿色显示。内部过渡元素的化合价壳由（ n ＆ndash; 2）组成。 f ，（ n ＆ndash; 1） d 和 ns 子外壳。当最后一个电子进入 f 轨道时，内部过渡元素构成 f 嵌段。填满每一行的 f 轨道的主要量子数等于行数减去2。在第六行中，填充了4 f 个轨道，在第七行中，填充了5 f 个轨道。内部有两个过渡系列：
 
 <ol>
 <li>镧系元素：镧（La）到镥（Lu）</ li>
 <li>锕系元素：锕（Ac）到铹（Lr）</ li>
 </ ol>
 
 由于镧和锕与该系列的其他成员相似，因此被包括在内并用于命名该系列，即使它们是不含 f 电子的过渡金属。
 
 本文改编自<a href="https://openstax.org/books/chemistry-2e/pages/6-4-electronic-structure-of-atoms-electron-configurations"> OpenStax 化学2e，第6.4节：原子的电子结构。</a>

元素周期表按照原子序数递增的顺序排列原子，使具有相同化学性质的元素周期性地重复出现。当它们的……

Education

教育

JoVE Core

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

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 some physical properties of elements.

The horizontal rows on the periodic table are periods. Moving across a period, each next element has one more proton in the nucleus and one more electron in the valence shell. The vertical columns are groups. Elements in the same group have the same number of valence electrons, which is why they often show similar chemical behavior. For example, lithium and sodium each have one valence electron, beryllium and magnesium each have two, and fluorine and chlorine each have seven. Because elements react by losing, gaining, or sharing valence electrons, their group placement helps predict how they will behave.

It is important to remember that the periodic table was built from chemical behavior before atomic structure was understood. Today, the pattern makes sense because elements with the same number of valence electrons are placed in the same group. The colored regions of the table also show three categories based on which orbitals are being filled. Main group elements, also called representative elements, are the elements whose last added electron enters an s or p orbital in the outermost shell. This category includes all nonmetals, the metalloids, and many metals. For main group elements, the valence electrons are the electrons with the highest n level. Gallium, for example, has the electron configuration [Ar] 4s2 3d10 4p1, so it has three valence electrons. The filled d orbitals are counted as core electrons, not valence electrons.

The two far-left columns form the s-block, and the six far-right columns form the p-block. The noble gases are part of the p-block. They usually have eight valence electrons, except helium, which has two. This helps explain why noble gases are highly stable and unreactive. Transition elements, or transition metals, are metallic elements whose last added electron enters a d orbital. Their valence electrons include the ns and (n - 1)d electrons added after the last noble gas configuration. By the official IUPAC definition, transition elements have partially filled d orbitals, so Zn, Cd, Hg, and also Cu, Ag, and Au are not technically transition elements, even though the term is often used for the whole d-block.

The d-block has 10 columns. As you move across each row, the d orbitals that fill have a principal quantum number that is one less than the row number. In the fourth row, 3d orbitals fill; in the fifth row, 4d orbitals fill; and so on. Inner transition elements form the f-block, where the last electron added enters an f orbital. Their valence shells include the (n - 2)f, the (n - 1)d, and the ns subshells. The f orbitals that fill across each row have a principal quantum number that is two less than the row number. In the sixth row, 4f orbitals fill, and in the seventh row, 5f orbitals fill. The two inner transition series are the lanthanides, from lanthanum through lutetium, and the actinides, from actinium through lawrencium. Lanthanum and actinium are included in those series because they are similar to the other members, even though they are transition metals with no f electrons.

How Valence Electrons Shape the Periodic Table

how-valence-electrons-shape-the-periodic-table

periodic classification of the elements

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: 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...

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

Learn how valence electrons explain periodic table groups, blocks, and element behavior, including main group, transition, lanthanide, and actinide elements.

How Valence Electrons Shape the Periodic Table | 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.1.6

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

CH.2

CH.2.b

CH.2.c

PS.2

PS.2.b

PS.4

PS.4.a

PS.4.b

Minnesota Academic Standards in Science

3.1.1 9C.2.1.1.1

9C.3.1.1.1

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.A

Alabama Course of Study Science

9-12.C.1.1

9-12.C.1.1.e

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

Florida Department of Education

SC.912.P.8

SC.912.P.8.5

Chemistry and Physics

IPC.7

IPC.7.A

IPC.7.B

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

C-PS1-2

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Structure and Properties of Matter

HS-PS1-1.

Georgia Standards of Excellence

SPS1.

Periodic Table Trends

SC1.

periodic-table-trends-atomic-radii-ionization-and-electronegativity

Periodic Table Trends: Atomic Radii, Ionization, and Electronegativity

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

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.

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

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 ...

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

PS.Chm.3.1

Analyze the structure of atoms and isotopes.

How Valence Electrons Shape the Periodic Table

Description

Transcript

Tags

More videos by Standards