化学元素周期表图规律特点,用英文叙述
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发布时间：2022-04-26 16:04
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时间：2023-10-07 22:01
The groups or vertical columns of the periodic table have traditionally been labeled from left to right using Roman numerals followed by the symbol a or b, the b referring to groups of transition elements. Another labeling scheme, which has been adopted by the International Union of Pure and Applied Chemistry (IUPAC), is gaining in popularity. This new system simply numbers the groups sequentially from 1 to 18 across the periodic table.
All the elements within a single group bear a considerable familial resemblance to one another and, in general, differ markedly from elements in other groups. For example, the elements of group 1 (or Ia), with the exception of hydrogen, are metals with chemical valence of +1; while those of group 17 (or VIIa), with the exception of astatine, are nonmetals, commonly forming compounds in which they have valences of -1.
In the periodic classification, noble gases, which in most cases are unreactive (valence = 0), are interposed between highly reactive metals that form compounds in which their valence is +1 on one side and highly reactive nonmetals forming compounds in which their valence is -1 on the other side. This phenomenon led to the theory that the periodicity of properties results from the arrangement of electrons in shells about the atomic nucleus. According to the same theory, the noble gases are normally inert because their electron shells are completely filled; other elements, therefore, may have some shells that are only partly filled, and their chemical reactivities involve the electrons in these incomplete shells. Thus, all the elements that occupy a position in the table preceding that of an inert gas have one electron less than the number necessary for completed shells and show a valence of -1, corresponding to the gain of one electron in reactions. Elements in the group following the inert gases in the table have one electron in excess of the completed shell structure and in reactions can lose that electron, thereby showing a valence of + 1.
An analysis of the periodic table, based on this theory, indicates that the first electron shell may contain a maximum of 2 electrons, the second builds up to a maximum of 8, the third to 18, and so on. The total number of elements in any one period corresponds to the number of electrons required to achieve a stable configuration. The distinction between the a and b subgroups of a given group also may be explained on the basis of the electron shell theory. Both subgroups have the same degree of incompleteness in the outermost shell but differ from each other with respect to the structures of the underlying shells. This model of the atom still provides a good explanation of chemical bonding.
There are 18 vertical columns, or groups, in the standard periodic table. At present, there are three versions of the periodic table, each with its own unique column headings, in wide use. The three formats are the old International Union of Pure and Applied Chemistry (IUPAC) table, the Chemical Abstract Service (CAS) table, and the new IUPAC table. The old IUPAC system labeled columns with Roman numerals followed by either the letter A or B. Columns 1 through 7 were numbered IA through VIIA, columns 8 through 10 were labeled VIIIA, columns 11 through 17 were numbered IB through VIIB and column 18 was numbered VIII. The CAS system also used Roman numerals followed by an A or B. This method, however, labeled columns 1 and 2 as IA and IIA, columns 3 through 7 as IIIB through VIB, column 8 through 10 as VIII, columns 11 and 12 as IB and IIB and columns 13 through 18 as IIIA through VIIIA. However, in the old IUPAC system the letters A and B were designated to the left and right part of the table, while in the CAS system the letters A and B were designated to the main group elements and transition elements respectively. (The preparer of the table arbitrarily could use either an upper-or lower-case letter A or B, adding to the confusion.) Further, the old IUPAC system was more frequently used in Europe while the CAS system was most common in America. In the new IUPAC system, columns are numbered with Arabic numerals from 1 to 18. These group numbers correspond to the number of s, p, and d orbital electrons added since the last noble gas element (in column 18). This is in keeping with current interpretations of the periodic law which holds that the elements in a group have similar configurations of the outermost electron shells of their atoms. Since most chemical properties result from outer electron interactions, this tends to explain why elements in the same group exhibit similar physical and chemical properties. Unfortunately, the system fails for the elements in the first 3 periods (or rows; see below). For example, aluminum, in the column numbered 13, has only 3 s, p, and d orbital electrons. Nevertheless, the American Chemical Society has adopted the new IUPAC system.
The horizontal rows of the table are called periods. The elements of a period are characterized by the fact that they have the same number of electron shells; the number of electrons in these shells, which equals the element's atomic number, increases from left to right within each period. In each period the lighter metals appear on the left, the heavier metals in the center, and the nonmetals on the right. Elements on the borderline between metals and nonmetals are called metalloids.
Group 1 (with one valence electron) and Group 2 (with two valence electrons) are called the alkali metals and the alkaline-earth metals, respectively. Two series of elements branch off from Group 3, which contains the transition elements, or transition metals; elements 57 to 71 are called the lanthanide series, or rare earths, and elements 89 to 103 are called the actinide series, or radioactive rare earths; a third set, the superactinide series (elements 122–153), is predicted to fall outside the main body of the table, but none of these has yet been synthesized or isolated. The nonmetals in Group 17 (with seven valence electrons) are called the halogens. The elements grouped in the final column (Group 18) have no valence electrons and are called the inert gases, or noble gases, because they react chemically only with extreme difficulty.
In a relatively simple type of periodic table, each position gives the name and chemical symbol for the element assigned to that position; its atomic number; its atomic weight (the weighted average of the masses of its stable isotopes, based on a scale in which carbon-12 has a mass of 12); and its electron configuration, i.e., the distribution of its electrons by shells. The only exceptions are the positions of elements 103 through 118; complete information on these elements has not been compiled. Larger and more complicated periodic tables may also include the following information for each element: atomic diameter or radius; common valence numbers or oxidation states; melting point; boiling point; density; specific heat; Young's molus; the quantum states of its valence electrons; type of crystal form; stable and radioactive isotopes; and type of magnetism exhibited by the element (paramagnetism or diamagnetism).
The layout of the periodic table demonstrates recurring ("periodic") chemical properties. Elements are listed in order of increasing atomic number (i.e., the number of protons in the atomic nucleus). Rows are arranged so that elements with similar properties fall into the same columns (groups or families). According to quantum mechanical theories of electron configuration within atoms, each row (period) in the table corresponded to the filling of a quantum shell of electrons. There are progressively longer periods further down the table, grouping the elements into s-, p-, d- and f-blocks to reflect their electron configuration.
In printed tables, each element is usually listed with its element symbol and atomic number; many versions of the table also list the element's atomic mass and other information, such as its abbreviated electron configuration, electronegativity and most common valence numbers.
As of 2006, the table contains 117 chemical elements whose discoveries have been confirmed. Ninety-four are found naturally on Earth, and the rest are synthetic elements that have been proced artificially in particle accelerators. Elements 43 (technetium), 61 (promethium) and all elements greater than 83 (bismuth), beginning with 84 (polonium) have no stable isotopes. The atomic mass of each of these element's isotope having the longest half-life is typically reported on periodic tables with parentheses.[1] Isotopes of elements 43, 61, 93 (neptunium) and 94 (plutonium), first discovered synthetically, have since been discovered in trace amounts on Earth as procts of natural radioactive decay processes.
The primary determinant of an element's chemical properties is its electron configuration, particularly the valence shell electrons. For instance, any atoms with four valence electrons occupying p orbitals will exhibit some similarity. The type of orbital in which the atom's outermost electrons reside determines the "block" to which it belongs. The number of valence shell electrons determines the family, or group, to which the element belongs.
The total number of electron shells an atom has determines the period to which it belongs. Each shell is divided into different subshells, which as atomic number increases are filled in roughly this order (the Aufbau principle):
Groups
Main article: Group (periodic table)
A group or family is a vertical column in the periodic table. Groups are considered the most important method of classifying the elements. In some groups, the elements have very similar properties and exhibit a clear trend in properties down the group. These groups tend to be given trivial (unsystematic) names, e.g., the alkali metals, alkaline earth metals, halogens, pnictogens, chalcogens, and noble gases. Some other groups in the periodic table display fewer similarities and/or vertical trends (for example Group 14), and these have no trivial names and are referred to simply by their group numbers.
Periods
Main article: Period (periodic table)
A period is a horizontal row in the periodic table. Although groups are the most common way of classifying elements, there are some regions of the periodic table where the horizontal trends and similarities in properties are more significant than vertical group trends. This can be true in the d-block (or "transition metals"), and especially for the f-block, where the lanthanoids and actinoids form two substantial horizontal series of elements.
Blocks
Main article: Periodic table block
This diagram shows the periodic table blocks.Because of the importance of the outermost shell, the different regions of the periodic table are sometimes referred to as periodic table blocks, named according to the subshell in which the "last" electron resides. The s-block comprises the first two groups (alkali metals and alkaline earth metals) as well as hydrogen and helium. The p-block comprises the last six groups (groups 13 through 18) and contains, among others, all of the semimetals. The d-block comprises groups 3 through 12 and contains all of the transition metals. The f-block, usually offset below the rest of the periodic table, comprises the rare earth metals.
Other
The chemical elements are also grouped together in other ways. Some of these groupings are often illustrated on the periodic table, such as transition metals, poor metals, and metalloids. Other informal groupings exist, such as the platinum group and the noble metals.
Periodicity of chemical properties
The main value of the periodic table is the ability to predict the chemical properties of an element based on its location on the table. It should be noted that the properties vary differently when moving vertically along the columns of the table than when moving horizontally along the rows.
Periodic trends of groups
Modern quantum mechanical theories of atomic structure explain group trends by proposing that elements within the same group have the same electron configurations in their valence shell, which is the most important factor in accounting for their similar properties. Elements in the same group also show patterns in their atomic radius, ionization energy, and electronegativity. From top to bottom in a group, the atomic radii of the elements increase. Since there are more filled energy levels, valence electrons are found farther from the nucleus. From the top, each successive element has a lower ionization energy because it is easier to remove an electron since the atoms are less tightly bound. Similarly, a group will also see a top to bottom decrease in electronegativity e to an increasing distance between valence electrons and the nucleus.
Periodic trends of periods
Periodic trend for ionization energy. Each period begins at a minimum for the alkali metals, and ends at a maximum for the noble gases.Elements in the same period show trends in atomic radius, ionization energy, electron affinity, and electronegativity. Moving left to right across a period, atomic radius usually decreases. This occurs because each successive element has an added proton and electron which causes the electron to be drawn closer to the nucleus. This decrease in atomic radius also causes the ionization energy to increase when moving from left to right across a period. The more tightly bound an element is, the more energy is required to remove an electron. Similarly, electronegativity will increase in the same manner as ionization energy because of the amount of pull that is exerted on the electrons by the nucleus. Electron affinity also shows a slight trend across a period. Metals (left side of a period) generally have a lower electron affinity than nonmetals (right side of a period) with the exception of the noble gases.
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时间：2023-10-07 22:01
（1）除第1周期外，其他周期元素（惰性气体元素除外）的原子半径随原子序数的递增而减小；
（2）同一族的元素从上到下，随电子层数增多，原子半径增大。
注意：原子半径在VIB族及此后各副族元素中出现反常现象。从钛至锆，其原子半径合乎规律地增加，这主要是增加电子层数造成的。然而从锆至铪，尽管也增加了一个电子层，但半径反而减小了，这是与它们对应的前一族元素是钇至镧，原子半径也合乎规律地增加（电子层数增加）。然而从镧至铪中间却经历了镧系的十四个元素，由于电子层数没有改变，随着有效核电荷数略有增加，原子半径依次收缩，这种现象称为“镧系收缩”。镧系收缩的结果抵消了从锆至铪由于电子层数增加到来的原子半径应当增加的影响，出现了铪的原子半径反而比锆小的“反常”现象。
2 元素化合价
（1）除第1周期外，同周期从左到右，元素最高正价由碱金属+1递增到+7，非金属元素负价由碳族-4递增到-1（氟无正价，氧无+6价，除外）；
（2）同一主族的元素的最高正价、负价均相同
(3) 所有单质都显零价
3 单质的熔点
（1）同一周期元素随原子序数的递增，元素组成的金属单质的熔点递增，非金属单质的熔点递减；
（2）同一族元素从上到下，元素组成的金属单质的熔点递减，非金属单质的熔点递增
4 元素的金属性与非金属性
（1）同一周期的元素电子层数相同。因此随着核电荷数的增加，原子越容易得电子，从左到右金属性递减，非金属性递增；
（2）同一主族元素最外层电子数相同，因此随着电子层数的增加，原子越容易失电子，从上到下金属性递增，非金属性递减。
5 最高价氧化物和水化物的酸碱性
元素的金属性越强，其最高价氧化物的水化物的碱性越强；元素的非金属性越强，最高价氧化物的水化物的酸性越强。
6 非金属气态氢化物
元素非金属性越强，气态氢化物越稳定。同周期非金属元素的非金属性越强，其气态氢化物水溶液一般酸性越强；同主族非金属元素的非金属性越强，其气态氢化物水溶液的酸性越弱。
7 单质的氧化性、还原性
一般元素的金属性越强，其单质的还原性越强，其氧化物的阳离子氧化性越弱；元素的非金属性越强，其单质的氧化性越强，其简单阴离子的还原性越弱。
翻译：
1 the atom radius
Except the first one (1), other elements of periodic cycles (inert gases except elements of the atom radius of atomic number increases with the decrease,
(2) the same group elements from top to bottom, with the increasing number of layers, the atom radius increased.
Note: in VIB atom radius and thereafter each FuZu elements appear abnormal phenomenon. From titanium and zirconium, its atomic radius increased meets regularly, which is mainly caused by the number of layers increase. However, despite comples from zirconium and also increases the radius of a layers, but instead, this is reced with their former gens element is atom radius, yttrium lanthanide to also fulfills the regular increase (increased) number of layers. However, from among the lanthanide to positively has experienced four elements of ten mind, because no change, with the number of layers of nuclear effectively increased slightly, the number of Hollywood atom radius, this kind of phenomenon in shrinkage is called "lanthanated contraction. Lanthanated department of offset from the shrinking e to the number of layers zirconium comples atom radius should increase the arrival of the increase of comples atom radius rather than the "freak" small zirconium phenomenon.
2 element combining
(1) in the first period, with period from left to right, elements of the highest general alkali + 1 to + 7, increasing by negative nonmetal elements carbon race - 4-1 (increasing oxygen is general, without exception, 6 +),
(2) the main elements of the highest of all the same general, negative
(3) all the elemental shows zero value
3 the end point
(1) the same cycle with atomic number of elements, the elements of the increasing elemental increase the melting metal melting point, nonmetal elemental descending,
(2) with gens elements from top to bottom, elements of the metal melting point, end point of increasing elemental nonmetal
4 elements of gold and nonmetallic sex
(1) the same number of elements as the electronic cycle. So with the increasing number of nuclear jose, atom is prone to electronics, from left to right, nonmetal sexual gold attribute increases,
(2) the same number of elements as the outermost electrons, therefore, the number of layers with increase of atomic more easily lost, from top to bottom, nonmetal sexual gold attributes.
Five highest oxide and natural gas hydrates acid alkali
Elements of gold, its highest the attributes of the natural gas hydrates alkaline oxide stronger, The stronger the nonmetal elements of 5.95 oxide hydrates, the stronger the acidic.
6 nonmetal gaseous hydride
Sex is stronger, nonmetal elements is more stable. Gaseous hydride With the cycle of nonmetal elements of the non-metallic, general acidic aqueous gas hydride stronger, With the main group nonmetal elements of the non-metallic sex, the gaseous hydride acidic aqueous solution.
7 the oxidizing, recing end
General elements of gold, its elemental attributes of the oxide, recing the cationic oxidizing weaker, The stronger the nonmetallic elements, the end of the oxidation, its simple anion recible weaker.
[editor this segment of the rule that element position]
In the periodic table of elements of judgment should remember rules:
(1) the number equals nuclear elements cycle count; electronic
(2) the main elements for the outermost electrons is ordinal number.
Yin and Yang ion radius distinguish rule
Due to the outermost electrons is anion and cation got electronic is lost
Therefore, the overall (the same element),
(1) cationic radius < atom radius
(2) anion > radius atom radius
(3) anion radius > cationic radius
(4) or words with the same, for the arrangement of nuclear electronic ion, atomic number is larger, the smaller the ion radius.
(not suitable for rare gases)
