Variation of physical Properties across a Period

The physics properties of aspects vary throughout a period, greatly as a function of bonding.

You are watching: Which best describes the trends in electronegativity on the periodic table?


Learning Objectives

Describe the basic variations in physics properties across a heat of the routine table.


Key Takeaways

Key PointsAs you relocate from left to right across a period, the physical properties the the aspects change.One loose trend is the tendency for elemental states to walk from solid to fluid to gas across a period. In the extreme cases, teams 1 and also 18, we view that Group-1 elements are every solids and Group-18 aspects are every gases.Many the the alters in physics properties as you cross a duration are due to the nature of the bonding interactions that the elements undergo. The facets on the left next of a period tend to type more ionic bonds, if those on the appropriate side form more covalent bonds.Key Termsboiling point: The temperature at which a fluid boils, with the vapor pressure equal come the given exterior pressure.melting point: The temperature at which the solid and also liquid phases that a substance are in equilibrium; the is relatively insensitive to changes in pressure.

The regular table of elements has a full of 118 entries. Elements are arranged in a collection of rows (periods) in stimulate of atomic number so that those with similar properties appear in vertical columns. Elements in the same duration have the same number of electron shells; moving throughout a duration (so proceeding from group to group), facets gain electrons and protons and also become less metallic. This plan reflects the routine recurrence of similar properties together the atomic number increases. Because that example, the alkali metals lie in one group (Group 1) and share similar properties, such together high reactivity and also the propensity to shed one electron to arrive at a noble-gas electron configuration.

Modern quantum mechanics explains these routine trends in nature in regards to electron shells. The filling of every shell corresponds to a heat in the table.

In the s-block and p-block the the periodic table, elements within the same period generally execute not exhibition trends and also similarities in properties (vertical patterns down teams are more significant). However, in the d-block, trends throughout periods come to be significant, and the f-block elements show a high level of similarity across periods (particularly the lanthanides).

If we research the physics state of each element, we notification that ~ above the left next of the table, elements such together lithium and beryllium space metallic solids, vice versa, on the right, nitrogen, oxygen, fluorine, and neon are all gases. This is because lithium and also beryllium type metallic solids, whereas the facets to the right type covalent compound with small intermolecular pressure holding castle together. Thus we deserve to say that, in general, elements tend to go from solids to liquids to gases as we move throughout a provided period. However, this is not a strict trend.

Bonding

As girlfriend move across a period in the periodic table, the varieties of commonly encountered bonding interaction change. Because that example, at the beginning of period 2, facets such together lithium and also beryllium type only ionic bonds, in general. Moving across the period, elements such as boron, carbon, nitrogen and also oxygen tend to form covalent bonds. Fluorine can form ionic bonds through some elements, such as carbon and boron, and neon go not have tendency to form any bonds in ~ all.

Melting clues of the Halides

Another physical building that varies throughout a period is the melting allude of the matching halide. A halide is a binary compound, of i beg your pardon one component is a halogen atom and also the other component is an element or radical the is less electronegative (or an ext electropositive) 보다 the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts room halides; the hal- syllable in halide and also halite shows this correlation. All team 1 metals kind halides that room white solids at room temperature.

The melting allude is associated to the strength of intermolecular bonds within the element. First, we should analyze compounds developed from elements from groups 1 and also 2 (e.g., sodium and also magnesium). To build an knowledge of bonding in these compounds, we emphasis on the halides of these elements. The physical properties the the chlorides of aspects in groups 1 and also 2 are an extremely different contrasted to the chlorides of the elements in groups 4, 5, and 6.

All of the alkali halides and alkaline planet halides are solids at room temperature and have melt points in the hundreds of levels centigrade. Because that example, the melting point of salt chloride (NaCl) is 808 °C. In contrast, the melting points the the non-metal halides from periods 2 and also 3, such as CCl4, PCl3, and also SCl2, are below 0 °C, so these materials are liquids in ~ room temperature. Furthermore, all of these compounds have actually low cook points, commonly in the range of 50 °C to 80 °C.

Melting and boiling points of miscellaneous halidesHalideMelting allude (ºC)Boiling suggest (ºC)
LiCl610º1382º
BeCl2405º488º
CCl4-23º77º
NCl3−40º71º
OCl2−20º
FCl−154º−101º
NaCl808º1465º
MgCl2714º1418º
SiCl4-68º57º
PCl3−91º74º
SCl2−122º59º
Cl2−102º−35º
KCl772º1407º
CaCl772º> 1600º

The non-metal halide liquids are also electrical insulators and do no conduct electrical current. In contrast, once an alkali halide or alkaline earth halide melts, the resulting liquid is great electrical conductor. This tells united state that this molten compounds consists ions, conversely, the non-metal halides carry out not. This again displayed the kind of bonding that these link exhibit: the left-most elements type more ionic bonds, and also the further-right facets tend to kind more covalent bonds.


Variation of physics Properties within a Group

The physical properties (notably, melting and boiling points) the the elements in a offered group differ as you move down the table.


Learning Objectives

Describe the basic trends of physical properties in ~ a group on the periodic table.


Key Takeaways

Key PointsThe physics properties of elements depend in part on your valence electron configurations. As this configuration continues to be the exact same within a group, physics properties tend to stay somewhat consistent.The most notable within-group changes in physics properties take place in teams 13, 14, and also 15, whereby the aspects at the height are non-metallic, while the aspects at the bottom room metals.The patterns in boiling and melting points vary from group to group, based upon the kind of non-bonding interaction holding the atom together.Key Termsphysical property: any kind of property the is measurable who value explains a physics system’s state.malleable: maybe to be hammered right into thin sheets; qualified of being prolonged or shaped by beating with a hammer or by the press of rollers.ductile: capable of being pulled or stretched into thin cable by mechanical force without breaking.

In chemistry, a group is a vertical pillar in the periodic table the the chemistry elements. There room 18 teams in the standard regular table, including the d-block elements but excluding the f-block elements. Each element within a group has similar physical or chemical properties because of its atom’s outermost electron covering (most chemical properties are conquered by the orbital place of the outermost electron).

Common physics Properties

A physical property of a pure substance can be defined as anything that can be observed without the identification of the substance changing. The monitorings usually consists some form of numerical measurement, although periodically there is a an ext qualitative (non-numerical) summary of the property. Physics properties incorporate such points as:

ColorBrittlenessMalleabilityDuctilityElectrical conductivityDensityMagnetismHardnessAtomic numberSpecific heatHeat the vaporizationHeat that fusionCrystalline configurationMelting temperatureBoiling temperatureHeat conductivityVapor pressureTendency to dissolve in assorted liquids

These are just a couple of of the measurable physical properties.

Within a group of the regular table, each element has the exact same valence electron configuration. Because that example, lithium, sodium, potassium, rubidium, cesium, and francium all have a single electron in an s orbital, vice versa, every aspect in the group including fluorine has the valence electron construction ns2np5, whereby n is the period. This means the aspects of a group often exhibit comparable chemical reactivity, and also there might be similarity in physical properties together well.

Boiling and Melting Points

Before a conversation of the melt points of various elements, it must be listed that some facets exist in various forms. Because that example, pure carbon have the right to exist as diamond, which has actually a very high melt point, or together graphite, whose melting allude is quiet high however much reduced than that of diamond.

Different groups exhibit various trends in boiling and melting points. For groups 1 and 2, the boiling and also melting point out decrease together you move down the group. Because that the transition metals, boiling and also melting point out mostly boost as you relocate down the group, however they decrease because that the zinc family. In the main group elements, the boron and carbon households (Groups 13 and 14) to decrease in their boiling and also melting points as you relocate down the group, conversely, the nitrogen, oxygen, and fluorine families (Groups 15, 16, and also 17) have tendency to rise in both. The noble gases (Group 18) to decrease in your boiling and also melting points under the group.

These phenomena have the right to be interpreted in relationship to the types of pressures holding the facets together. For metallic species, the metallic bonding communication (electron-sharing) i do not care more difficult as the aspects get larger (toward the bottom of the table), resulting in the forces holding them with each other to come to be weaker. Together you move right follow me the table, however, polarizability and also van der Waals interaction predominate, and also as bigger atoms are much more polarizable, they often tend to exhibit more powerful intermolecular forces and therefore higher melting and boiling points.

Metallic Character

Metallic elements are shiny, normally gray or silver in color, and conductive that heat and electricity. They room malleable (can it is in hammered into thin sheets) and also ductile (can it is in stretched into wires). Some metals, such as sodium, are soft and also can be cut with a knife. Others, such as iron, are really hard. Non-metallic atoms space dull and also are poor conductors. They space brittle as soon as solid, and many are gases at STP (standard temperature and pressure). Metals provide away their valence electrons once bonding, whereas non-metals often tend to take it electrons.


A metal and also a non-Metal: on the left is sodium, a really metallic facet (ductile, malleable, conducts electricity). ~ above the ideal is sulfur, a an extremely non-metallic element.


Metallic character boosts from ideal to left and also from optimal to bottom on the table. Non-metallic character adheres to the opposite pattern. This is since of the various other trends: ionization energy, electron affinity, and electronegativity. Girlfriend will an alert a jagged line running with the periodic table starting between boron and aluminum – this is the separation between metallic and also non-metallic elements, v some facets close to the heat exhibiting features of each. The steels are toward the left and also center that the periodic table, in the s, d, and f blocks. Negative metals and metalloids (somewhat metal, somewhat non-metal) room in the lower left of the p block. Non-metals space on the ideal of the table.


Electron Configurations and Magnetic nature of Ions

The electron configuration of a given facet can it is in predicted based on its ar in the routine table.


Learning Objectives

Predict the form of ions an facet will kind based ~ above its place in the regular table


Key Takeaways

Key PointsThe electron configuration of an element dictates the element’s properties in a chemistry reaction. Electron configurations vary regularly along the periodic table.The Aufbau principle determines the electron configuration of an element. The principle claims that the lowest- power orbitals space filled first, followed successively by higher-energy orbitals.Magnetism can an outcome from unpaired electron in a given ion of an element, depending on the spin states of the electrons.Key Termselectron configuration: The arrangement of electron in one atom, molecule, or other physical structure, such as a crystal.

Blocks of the periodic Table

The routine table does much more than simply list the elements. Words “periodic” means that within each row, or period, the aspects show a sample of characteristics. This is due to the fact that the aspects are detailed in part by their electron configuration.


Blocking in the periodic table: The routine table can be damaged into blocks, corresponding to the highest energy electrons.


The alkali metals and alkaline planet metals have one and also two valence electrons (electrons in the external shell), respectively; due to the fact that of this, they shed electrons to type bonds easily and so are really reactive. These facets comprise the s block the the regular table. The ns block, on the right, contains typical non-metals, such together chlorine and also helium. The noble gases, in the shaft on the right, nearly never react, due to the fact that they have actually eight valence electrons forming a stable external shell. The halogens, directly to the left of the noble gases, readily obtain electrons and also react v metals. The s and p blocks make up the main- group elements, additionally known together representative elements. The d block, which is the largest, consists of shift metals, such as copper, iron, and also gold. The f block, ~ above the bottom, contains rarer metals, including uranium. Facets in the same group or household have the exact same configuration that valence electrons, so they law in chemically similar ways.


Periodic table of the elements: This photo is color-coded to display the s, p, d, and f block of the regular table.


Electron Configuration

In atomic physics and also quantum chemistry, the electron configuration is the distribution of electron of an atom or molecule in atom or molecule orbitals. Because that example, the electron configuration of the neon atom (Ne) is 1s2 2s2 2p6. Follow to the legislations of quantum mechanics, a details energy is linked with every electron configuration. Under specific conditions, electrons have the right to move from one orbital to an additional by emissions or absorb of a quantum of energy, in the type of a photon.

Knowledge that the electron configuration of different atoms is beneficial in knowledge the framework of the routine table. The principle is likewise useful because that describing the chemistry bonds that hold atoms together. In bulk materials, this same idea helps explain the peculiar properties the lasers and also semiconductors.

The idea of one electron construction was first conceptualized under the Bohr model of the atom, and it is still usual to speak that “shells” and “subshells” in spite of the breakthroughs in expertise of the quantum-mechanical nature of electrons.

Aufbau Principle

The Aufbau principle (from the German Aufbau, an interpretation “building up, construction;” additionally called the Aufbau dominion or building-up principle) is supplied to identify the electron construction of one atom, molecule, or ion. The rule postulates a hypothetical process in i beg your pardon an atom is “built up” by the progressive enhancement of electrons. Together electrons are added, they assume their most stable positions (electron orbitals) with respect come the nucleus and the electrons that are already there.

According come the principle, electrons to fill orbitals starting at the lowest accessible energy state prior to filling greater states (e.g., 1s prior to 2s). The number of electrons that have the right to occupy every orbital is limited by the Pauli exemption principle. If many orbitals the the same power are available, Hund’s ascendancy states the unoccupied orbitals will certainly be filled before occupied orbitals space reused (by electrons having various spins).


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Atomic orbitals notified by increasing energy: bespeak in which orbitals space arranged by increasing power according to the Madelung rule. Every diagonal red arrowhead corresponds to a different value of n + l.


Magnetism

Magnetism is a residential property of products that respond come an used magnetic field. Long-term magnets have persistent magnetic areas caused through ferromagnetism, the strongest and also most familiar type of magnetism. However, all materials are influenced in different way by the visibility of a magnetic field. Some are attracted to a magnetic field (paramagnetism); others space repulsed by that (diamagnetism); quiet others have actually a much more complicated relationship v an applied magnetic ar (e.g., spin-glass behavior and antiferromagnetism). Building materials that space negligibly affected by magnetic areas are considered non-magnetic, this are: copper, aluminum, gases, and also plastic. Pure oxygen exhibits magnetic properties once cooled come a fluid state.

The magnetic properties of a given aspect depend on the electron configuration of that element, i m sorry will readjust when the element loses or gains an electron to kind an ion. If the ionization the an element yields an ion through unpaired electrons, this electrons might align the sign of their spins in the presence of a magnetic field, making the material paramagnetic. If the spins often tend to align spontaneously in the absence of a magnetic field, the resulting species is termed ferromagnetic.


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Hierarchy for various varieties of magnetism: There space various types of magnetism determined to date that can be arranged in a hierarchy.


Applications that Magnetism

A lodestone, or loadstone, is a naturally magnetized piece of the mineral magnetite (Fe3O4). Old people an initial discovered the home of magnetism in lodestone. Piece of lodestone, suspended so they can turn, were the very first magnetic compasses, and also their importance to beforehand navigation is suggested by their an extremely name, i beg your pardon in middle English method “course stone” or “leading stone.” Lodestone is one of only 2 minerals that is found naturally magnetized; the other, pyrrhotite, is only weakly magnetic.


Atomic Radius

Atomic radii decrease indigenous left to right throughout a duration and increase from peak to bottom along a group.


Learning Objectives

Predict the relative atomic sizes of the aspects based top top the basic trends in atomic radii because that the periodic table.


Key Takeaways

Key PointsThe atomic radius that a chemical element is a measure up of the size of its atoms, generally the mean or common distance from the nucleus to the boundary of the neighboring cloud that electrons.Since the border is no a well-defined physics entity, there are various non-equivalent definitions of atomic radius.The regular trends that the atomic radii (and of assorted other chemical and also physical properties of the elements) can be defined by the electron covering theory of the atom.Key Termsquantum theory: A theory occurred in at an early stage 20th century, follow to i m sorry nuclear and also radiation phenomena deserve to be explained by presume that power only wake up in discrete quantities called quanta.electron shell: The cumulative states of all electrons in an atom having actually the same primary quantum number (visualized together an orbit in i m sorry the electron move).noble gas: any of the aspects of group 18 the the regular table, being monatomic and also (with very minimal exceptions) inert.

In chemistry, regular trends space the tendencies of details elemental characteristics to increase or decrease as one progresses follow me a row or shaft of the regular table of elements. The atomic radius is one together characteristic that trends across a period and down a group of the routine table.


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Periodic trends: A graphic showing all at once periodic patterns in the regular table.


Meaning that the atom Radius

The atomic radius of a chemical aspect is a measure up of the dimension of its atoms, generally the average or common distance from the nucleus to the border of the surrounding cloud the electrons. Since the border is not a well-defined physical entity, over there are assorted non-equivalent meanings of atomic radius.

Depending top top context, the term atomic radius may apply only to isolated atoms, or additionally to atoms in condensed matter, covalently bound in molecules, or in ionized and also excited states. The value of an atomic radius might be derived through experimental measurements or computed through theoretical models. Under part definitions, the worth of a radius might depend top top the atom’s state and context. Because that our purposes, we are generally looking at atom in their elemental state.


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Sizes the atoms and their ions in picometers (pm): Red numbers space ionic radii that cations, black color numbers are for neutral species, and blue numbers room for anions.


Atomic radii vary in a predictable and also explicable manner across the routine table. Radii typically decrease from left to ideal along each period (row) of the table, from the alkali steels to the noble gases; radii boost down each group (column). The radius rises sharply in between the noble gas at the finish of each duration and the alkali metal at the beginning of the next period. These patterns of the atomic radii (and of various other chemical and also physical properties of the elements) have the right to be explained by the electron shell theory of the atom. Radii measurements listed important proof for the breakthrough and check of quantum theory.

Explanation that the general Trends

The means atomic radius different with enhancing atomic number can be explained by the arrangement of electrons in shells of addressed capacity. Shells closer come the nucleus—those through a smaller sized radius—are generally filled first, since the negatively charged electrons are attracted by the positive charged proton in the nucleus. As the atom number increases along a heat of the regular table, added electrons are added to the same, outermost shell. The radius the this shell slowly contracts together the attraction in between the extr electrons and the cell nucleus increases. In a noble gas, the outermost shell is fully filled. Therefore, the added electron of following alkali metal (one row under on the routine table) will go into a brand-new outer shell, audit for the sudden boost in the atomic radius.


Atomic number to radius graph: A chart reflecting the atomic radius loved one to the atomic variety of the elements.


The increasing nuclear charge is partly counterbalanced through the increasing number of electrons, a phenomenon that is well-known as shielding; this explains why the size of atom usually increases down every column. Underlying causes of the regular trends in atom radius additionally have an affect on various other chemical and also physical properties of the elements.


Ionic Radius

Similarly fee ions often tend to diminish in size across a duration (row) and also increase in dimension down a group (column).


Key Takeaways

Key PointsThe ionic radius is the distance between the nucleus and the electron in the outermost covering of one ion.When one atom loser an electron to form a cation, the lost electron no longer contributes to shielding the various other electrons from the charge of the nucleus; consequently, the other electrons are much more strongly attracted to the nucleus, and the radius the the atom gets smaller.When an electron is included to one atom, developing an anion, the included electron repels various other electrons, resulting in boost in the size of the atom.The trend observed in dimension of ionic radii is as result of shielding that the outermost electrons by the inner-shell electrons so that the outer shell electrons execute not “feel” the whole positive charge of the nucleus.Key Termscation: A positively fee ion, together opposed to an anion.ion: an atom or team of atom bearing an electrical charge, such as the sodium and also chlorine atoms in a salt solution.anion: A negatively charged ion, together opposed come a cation.

In chemistry, routine trends room the tendencies of certain elemental features to rise or decrease along a duration (row) or team (column) that the periodic table of elements. Ionic radius (rion) is the radius of an ion, nevertheless of even if it is it is an anion or a cation. Although no atoms no one ions have sharp boundaries, the is advantageous to act them together if lock are tough spheres with radii. In this way, the sum of ionic radii that a cation and an anion can give us the distance between the ions in a decision lattice. Ionic radii are frequently given in units of either picometers (pm) or Angstroms (Å), through 1 Å = 100 pm. Common values selection from 30 pm (0.3 Å) to over 200 afternoon (2 Å).

Trends in Ionic Radii

Ions might be bigger or smaller than the neutral atom, depending upon the ion’s charge. When an atom loses an electron to form a cation, the lost electron no much longer contributes come shielding the various other electrons native the fee of the nucleus; consequently, the other electrons are much more strongly attractive to the nucleus, and the radius of the atom it s okay smaller. Similarly, when an electron is included to an atom, creating an anion, the added electron repels other electrons, resulting in rise in the dimension of the atom.

The ionic radius is not a fixed residential property of a offered ion; rather, that varies through coordination number, turn state, and other parameters. Because that our purposes, we room considering the ions to be as close to your ground state as possible. Nevertheless, ionic radius values space sufficiently transferable to permit periodic trends to it is in recognized.


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Sizes the atoms and their ions: loved one sizes of atoms and also ions. The neutral atoms room colored gray, cations red, and anions blue.


As through other species of atomic radii, ionic radii rise upon to decrease a group and decrease going across a period. Note that this only applies if the facets are the same kind of ion, one of two people cations or anions. Because that example, if neutral lithium is bigger than neutral fluorine, the lithium cation is lot smaller 보다 the fluorine anion, due to the lithium cation having actually a various highest energy shell.


Ionization Energy

The ionization power tends to rise as one moves from left come right across a given period or increase a group in the routine table.


Key Takeaways

Key PointsThe ionization power is the energy required to eliminate an electron from its orbital roughly an atom come a suggest where it is no longer connected with that atom.The ionization energy of an element increases together one moves throughout a duration in the routine table due to the fact that the electrons are hosted tighter through the higher effective nuclear charge.The ionization energy of the facets increases together one move up a offered group due to the fact that the electrons are hosted in lower-energy orbitals, closer come the nucleus and also therefore are an ext tightly bound (harder come remove).Key Termsionization energy: The energy needed to eliminate an electron from an atom or molecule come infinity.

Periodic fads in the Ionization Energy

The ionization energy of a chemical species (i.e., one atom or molecule ) is the energy required to remove electrons native gaseous atom or ions. This residential property is additionally referred to as the ionization potentia and also is measure up in volts. In chemistry, it regularly refers to one mole the a problem (molar ionization energy or enthalpy) and also is report in kJ/mol. In atomic physics, the ionization energy is commonly measured in the unit electron volt (eV). Large atoms or molecules have low ionization energy, while small molecules tend to have higher ionization energies.

The ionization energy is various for electron of various atomic or molecular orbitals. An ext generally, the nth ionization energy is the power required to piece off the nth electron after the first n-1 electrons have actually been removed. The is considered a measure of the tendency of one atom or ion come surrender an electron or the stamin of the electron binding. The higher the ionization energy, the more difficult it is to eliminate an electron. The ionization energy may be an indicator of the reactivity of an element. Aspects with a low ionization energy tend to it is in reducing agents and type cations, i m sorry in turn incorporate with anions to kind salts.


Ionization energy: This graph reflects the first ionization power of the aspects in electron volts.


Moving left to right within a period or upward within a group, the first ionization power generally increases. Together the atomic radius decreases, it i do not care harder to eliminate an electron the is closer to a much more positively charged nucleus. Conversely, as one progresses under a team on the periodic table, the ionization power will most likely decrease because the valence electrons space farther away from the nucleus and also experience better shielding. They suffer a weaker attraction to the optimistic charge the the nucleus. Ionization power increases indigenous left to best in a duration and reduce from peak to bottom in a group.

Rationale because that the routine Trends in Ionization Energy

The ionization energy of an facet increases as one moves across a period in the regular table since the electrons are hosted tighter through the higher effective nuclear charge. This is because added electrons in the very same shell perform not substantially add to shielding each other from the nucleus, however boost in atom number corresponds to an increase in the number of protons in the nucleus.

The ionization power of the facets increases as one moves up a given group due to the fact that the electrons are held in lower-energy orbitals, closer to the nucleus and thus an ext tightly bound (harder come remove).

Based top top these two principles, the easiest element to ionize is francium and also the hardest to ionize is helium.


Key Takeaways

Key PointsThe electron affinity of one atom or molecule is the propensity for that bit to acquire an electron. This is an exothermic procedure for every non-noble gas elements.There are basic trends in electron affinity across and down the regular table the elements. Electron affinity normally increases throughout a period in the regular table and also sometimes decreases down a group.These trends are not have to universal.The chemistry rationale for alters in electron affinity across the regular table is the increased reliable nuclear charge across a period and up a group.Key Termselectron affinity: The electron affinity of an atom or molecule is characterized as the amount of power released as soon as an electron is added to a neutral atom or molecule to form a an adverse ion.electronegativity: The tendency of one atom or molecule to lure electrons come itself.

The electron affinity (Eea) the a neutral atom or molecule is defined as the lot of power released as soon as an electron is added to it to form a negative ion, together demonstrated by the following equation:

X(g) + e^- ightarrow X^-(g)

Electron affinity is measured because that atoms and molecules in the gaseous state only, since in the heavy or liquid states their energy levels would certainly be readjusted by call with various other atoms or molecules. Robert S. Mulliken supplied a list of electron affinities to construct an electronegativity scale for atom by finding the average of the electron affinity and also ionization potential. A molecule or atom that has a much more positive electron affinity value is often referred to as an electron acceptor; one through a less positive electron affinity is referred to as an electron donor. With each other they might undergo charge-transfer reactions.

To usage electron affinities properly, that is important to keep track of the sign. For any reaction that releases energy, the readjust in energy (ΔE) has actually a an adverse value, and the reaction is referred to as an exothermic process. Electron record for nearly all non-noble gas atoms entails the release of energy and also therefore is an exothermic process.


Confusion may arise in mistaking Eea for ΔE. The numbers noted in tables the Eea space all positive because they room magnitudes; the values of Eea in a table that electron six all suggest the amount of energy released when an electron is added to one element. Due to the fact that the relax of energy is constantly an exothermic event, these every correspond to an adverse values that ΔE (indicating one exothermic process).

Periodic trends in Electron Affinity

Although Eea different greatly across the periodic table, some patterns emerge. Generally, nonmetals have more positive Eea than metals. Atoms, together as group 7 elements, whose anions are more stable 보다 neutral atoms have actually a greater Eea. The electron six of the noble gases have not been conclusively measured, for this reason they may or might not have actually slightly negative values. Chlorine has the greatest Eea while mercury has the lowest.

Eea usually increases throughout a period (row) in the routine table, as result of the pour it until it is full of the valence shell of the atom. For instance, in ~ the same period, a Group-17 atom releases much more energy 보다 a Group-1 atom upon gaining an electron since the added electron create a to fill valence shell and also therefore is an ext stable.

A trend of diminish Eea down the teams in the routine table would certainly be expected, due to the fact that the extr electron is start an orbital farther away from the nucleus. Because this electron is furthermore away, it should be much less attracted come the nucleus and also release less power when added. However, this trend uses only to Group-1 atoms. Electron affinity adheres to the tendency of electronegativity: fluorine (F) has actually a higher electron affinity than oxygen (O), and so on.

The trends provided here room very similar to those in ionization energy and adjust for similar (though opposing) reasons.

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Electron affinities in the routine table: This table mirrors the electron six in kJ/mol because that the facets in the periodic table.