Variation of physics Properties throughout a Period

The physical properties of elements vary across a period, mostly as a role of bonding.

You are watching: As you move left to right in a period the reactivity of a metal


Learning Objectives

Describe the general variations in physical properties across a row of the periodic table.


Key Takeaways

Key PointsAs you relocate from left to right across a period, the physical properties the the aspects change.One loosened trend is the tendency for elemental says to go from heavy to fluid to gas throughout a period. In the excessive cases, groups 1 and also 18, we watch that Group-1 facets are all solids and Group-18 aspects are every gases.Many the the alters in physics properties together you cross a period are due to the nature that the bonding interactions the the aspects undergo. The elements on the left next of a period tend to kind more ionic bonds, when those top top the ideal side type more covalent bonds.Key Termsboiling point: The temperature in ~ which a liquid boils, with the vapor push equal to the given exterior pressure.melting point: The temperature at which the solid and liquid phases the a substance room in equilibrium; the is fairly insensitive to changes in pressure.

The routine table of aspects has a complete of 118 entries. Elements are arranged in a collection of rows (periods) in bespeak of atomic number so the those with comparable properties show up in upright columns. Aspects in the same duration have the same number of electron shells; moving across a duration (so advancing from group to group), facets gain electrons and also protons and also become less metallic. This plan reflects the periodic recurrence of similar properties as the atom number increases. Because that example, the alkali steels lie in one team (Group 1) and also share similar properties, such together high reactivity and also the propensity to shed one electron to come at a noble-gas electron configuration.

Modern quantum mechanics describes these routine trends in properties in terms of electron shells. The filling of every shell corresponds to a row in the table.

In the s-block and p-block the the routine table, facets within the same period generally do not exhibit trends and also similarities in properties (vertical fads down teams are more significant). However, in the d-block, trends across periods become significant, and also the f-block aspects show a high degree of similarity across periods (particularly the lanthanides).

If we research the physics state of each element, we notice that top top the left next of the table, facets such as lithium and also beryllium room metallic solids, conversely, on the right, nitrogen, oxygen, fluorine, and neon space all gases. This is because lithium and also beryllium kind metallic solids, vice versa, the facets to the right form covalent compounds with small intermolecular pressure holding them together. Because of this we deserve to say that, in general, elements tend to walk from solids come liquids to gases as we move throughout a provided period. However, this is not a strictly trend.

Bonding

As friend move across a period in the periodic table, the varieties of typically encountered bonding interaction change. Because that example, at the start of duration 2, aspects such as lithium and also beryllium kind only ionic bonds, in general. Moving across the period, aspects such as boron, carbon, nitrogen and also oxygen tend to type covalent bonds. Fluorine can kind ionic bonds with some elements, such together carbon and also boron, and neon go not have tendency to type any bonds at all.

Melting points of the Halides

Another physical building that varies throughout a period is the melting allude of the corresponding halide. A halide is a binary compound, of which one component is a halogen atom and the other part is an aspect or radical that is much less electronegative (or an ext electropositive) than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Plenty of salts space halides; the hal- rate in halide and halite shows this correlation. All team 1 metals form halides that room white solids in ~ room temperature.

The melting point is associated to the stamin of intermolecular bonds in ~ the element. First, we have to analyze compounds formed from aspects from groups 1 and also 2 (e.g., sodium and magnesium). To construct an knowledge of bonding in this compounds, we emphasis on the halides of these elements. The physical properties the the chlorides of facets in groups 1 and also 2 are an extremely different compared to the chlorides the the elements in teams 4, 5, and 6.

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

Melting and boiling point out of assorted halidesHalideMelting suggest (ºC)Boiling point (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 also do not conduct electric current. In contrast, as soon as an alkali halide or alkaline planet halide melts, the resulting liquid is wonderful electrical conductor. This tells united state that this molten compounds covers ions, whereas the non-metal halides perform not. This again displayed the type of bonding the these compound exhibit: the left-most elements form more ionic bonds, and also the further-right aspects tend to type more covalent bonds.


Variation of physical Properties within a Group

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


Learning Objectives

Describe the general trends of physical properties within a team on the periodic table.


Key Takeaways

Key PointsThe physics properties of elements depend in component on your valence electron configurations. Together this configuration remains the same within a group, physics properties tend to continue to be somewhat consistent.The most notable within-group transforms in physical properties occur in teams 13, 14, and also 15, whereby the facets at the top are non-metallic, when the aspects at the bottom are metals.The fads in boiling and melting points differ from group to group, based upon the form of non-bonding interaction holding the atom together.Key Termsphysical property: any type of property that is measurable whose value describes a physics system’s state.malleable: able to be hammered into thin sheets; capable of being prolonged or shaped by beating v a hammer or by the pressure of rollers.ductile: capable of gift pulled or stretched right into thin cable by mechanical pressure without breaking.

In chemistry, a group is a vertical column in the periodic table the the chemistry elements. There space 18 teams in the standard regular table, consisting of the d-block elements but not included the f-block elements. Each aspect within a group has similar physical or chemical properties because of that atom’s outermost electron shell (most chemical properties are dominated by the orbital place of the outermost electron).

Common physics Properties

A physical residential or commercial property of a pure substance can be identified as anything that have the right to be observed there is no the identity of the problem changing. The monitorings usually consists some form of numerical measurement, although sometimes there is a much more qualitative (non-numerical) description of the property. Physics properties encompass such things as:

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

These are just a few of the measurable physics properties.

Within a group of the periodic table, each facet has the very same valence electron configuration. For example, lithium, sodium, potassium, rubidium, cesium, and francium all have a solitary electron in one s orbital, conversely, every element in the team including fluorine has the valence electron construction ns2np5, whereby n is the period. This way the aspects of a group regularly exhibit comparable chemical reactivity, and there might be similarity in physics properties together well.

Boiling and also Melting Points

Before a conversation of the melting points of various elements, it must be listed that some facets exist in various forms. For example, pure carbon can exist together diamond, which has a really high melt point, or together graphite, who melting suggest is tho high but much reduced than the of diamond.

Different teams exhibit different trends in boiling and melting points. For groups 1 and also 2, the boiling and melting point out decrease as you move down the group. Because that the change metals, boiling and melting clues mostly increase as you move down the group, however they decrease for the zinc family. In the main team elements, the boron and also carbon households (Groups 13 and 14) to decrease in your boiling and also melting points as you relocate down the group, whereas the nitrogen, oxygen, and fluorine family members (Groups 15, 16, and 17) often tend to increase in both. The noble gases (Group 18) diminish in your boiling and melting points down the group.

These phenomena can be understood in relationship to the varieties of forces holding the elements together. For metallic species, the metallic bonding communication (electron-sharing) i do not care more an overwhelming as the facets get larger (toward the bottom of the table), bring about the forces holding them together to end up being weaker. As you move right along the table, however, polarizability and van der Waals interactions predominate, and also as larger atoms are more polarizable, they have tendency to exhibit more powerful intermolecular forces and therefore higher melting and boiling points.

Metallic Character

Metallic elements are shiny, generally gray or silver in color, and conductive the heat and electricity. They are malleable (can it is in hammered right into thin sheets) and ductile (can it is in stretched right into wires). Part metals, such together sodium, room soft and also can be cut with a knife. Others, such as iron, are very hard. Non-metallic atoms space dull and are bad conductors. They space brittle when solid, and many room gases in ~ STP (standard temperature and pressure). Metals give away their valence electrons once bonding, vice versa, non-metals have tendency to take electrons.


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


Metallic character boosts from ideal to left and also from optimal to bottom ~ above the table. Non-metallic character complies with the the contrary pattern. This is because of the various other trends: ionization energy, electron affinity, and also electronegativity. Friend will notice a jagged line running through the routine table starting between boron and aluminum – this is the separation in between metallic and also non-metallic elements, through some facets close come the line exhibiting features of each. The steels are toward the left and also center that the routine table, in the s, d, and also f blocks. Poor metals and also metalloids (somewhat metal, rather non-metal) room in the lower left that the ns block. Non-metals room on the right of the table.


Electron Configurations and Magnetic properties of Ions

The electron construction of a given element can be predicted based upon its location in the routine table.


Learning Objectives

Predict the type of ions an aspect will form based ~ above its position in the routine table


Key Takeaways

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

Blocks that the routine Table

The routine table does more than simply list the elements. Words “periodic” way that within each row, or period, the elements show a sample of characteristics. This is since the aspects are detailed in component by your electron configuration.


Blocking in the periodic table: The periodic table deserve to be broken into blocks, matching to the highest energy electrons.


The alkali metals and also alkaline planet metals have one and two valence electron (electrons in the external shell), respectively; because of this, they shed electrons to type bonds easily and also so are an extremely reactive. These aspects comprise the s block that the routine table. The p block, ~ above the right, contains typical non-metals, such as chlorine and helium. The noble gases, in the column on the right, almost never react, due to the fact that they have actually eight valence electrons creating a stable external shell. The halogens, directly to the left the the noble gases, readily obtain electrons and react through metals. The s and p blocks make up the main- group elements, likewise known as representative elements. The d block, which is the largest, is composed of change metals, such together copper, iron, and also gold. The f block, top top the bottom, includes rarer metals, including uranium. Elements in the same group or family members have the very same configuration of valence electrons, for this reason they act in chemically similar ways.


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


Electron Configuration

In atomic physics and quantum chemistry, the electron construction is the distribution of electron of one atom or molecule in atomic or molecule orbitals. For example, the electron configuration of the neon atom (Ne) is 1s2 2s2 2p6. According to the legislations of quantum mechanics, a specific energy is linked with each electron configuration. Under particular conditions, electrons can move indigenous one orbit to an additional by emission or absorption of a quantum that energy, in the form of a photon.

Knowledge that the electron configurations of different atoms is beneficial in knowledge the framework of the routine table. The ide is additionally useful for describing the chemistry bonds that host atoms together. In bulk materials, this very same idea helps define the strange properties of lasers and also semiconductors.

The idea of one electron configuration was an initial conceptualized under the Bohr design of the atom, and also it is still common to speak of “shells” and “subshells” in spite of the breakthroughs in understanding of the quantum-mechanical nature the electrons.

Aufbau Principle

The Aufbau rule (from the German Aufbau, meaning “building up, construction;” likewise called the Aufbau ascendancy or building-up principle) is supplied to identify the electron construction of an atom, molecule, or ion. The principle postulates a hypothetical process in i beg your pardon an atom is “built up” through the progressive enhancement of electrons. As electrons room added, they i think their many stable location (electron orbitals) through respect come the nucleus and the electrons the are currently there.

According to the principle, electrons to fill orbitals beginning at the lowest easily accessible energy state before filling greater states (e.g., 1s before 2s). The number of electrons that deserve to occupy every orbital is minimal by the Pauli exemption principle. If multiple orbitals that the same power are available, Hund’s preeminence states that unoccupied orbitals will certainly be filled before occupied orbitals space reused (by electrons having different spins).


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Atomic orbitals ordered by increasing energy: bespeak in i m sorry orbitals room arranged by increasing energy according come the Madelung rule. Each diagonal red arrowhead corresponds come a various value the n + l.


Magnetism

Magnetism is a building of products that respond to an applied magnetic field. Permanent magnets have persistent magnetic fields caused by ferromagnetism, the strongest and most familiar kind of magnetism. However, all products are influenced in different ways by the presence of a magnetic field. Some room attracted to a magnetic ar (paramagnetism); others are repulsed by that (diamagnetism); still others have actually a lot more facility relationship with an used magnetic field (e.g., spin-glass behavior and also antiferromagnetism). Building material that room negligibly affected by magnetic fields are thought about non-magnetic, this are: copper, aluminum, gases, and plastic. Pure oxygen exhibits magnetic properties as soon as cooled come a fluid state.

The magnetic properties of a given aspect depend on the electron construction of that element, i m sorry will readjust when the facet loses or profit an electron to type an ion. If the ionization that an facet yields an ion through unpaired electrons, these electrons might align the authorize of their spins in the existence of a magnetic field, making the product paramagnetic. If the spins have tendency to align spontaneously in the absence of a magnetic field, the resulting varieties is termed ferromagnetic.


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Hierarchy because that various types of magnetism: There space various species of magnetism determined to day that can be arranged in a hierarchy.


Applications the Magnetism

A lodestone, or loadstone, is a normally magnetized piece of the mineral magnetite (Fe3O4). Old people first discovered the building of magnetism in lodestone. Piece of lodestone, suspended for this reason they could turn, to be the first magnetic compasses, and their prominence to at an early stage navigation is suggested by their an extremely name, i beg your pardon in middle English method “course stone” or “leading stone.” Lodestone is among only 2 minerals the is discovered naturally magnetized; the other, pyrrhotite, is only weakly magnetic.


Atomic Radius

Atomic radii decrease from left to right across a duration and boost from peak to bottom follow me a group.


Learning Objectives

Predict the loved one atomic size of the aspects based on the general trends in atomic radii for the regular table.


Key Takeaways

Key PointsThe atomic radius the a chemical facet is a measure of the size of that atoms, generally the typical or typical distance from the nucleus to the border of the surrounding cloud the electrons.Since the border is no a well-defined physics entity, there are various non-equivalent meanings of atomic radius.The periodic trends of the atomic radii (and of miscellaneous other chemical and physical nature of the elements) can be described by the electron shell theory of the atom.Key Termsquantum theory: A theory arisen in at an early stage 20th century, according to which nuclear and radiation phenomena can be defined by presume that power only occurs in discrete amounts called quanta.electron shell: The cumulative states of all electrons in one atom having actually the same principal quantum number (visualized together an orbit in i beg your pardon the electrons move).noble gas: any of the aspects of team 18 of the regular table, being monatomic and also (with very limited exceptions) inert.

In chemistry, routine trends are the tendencies of specific elemental qualities to increase or decrease as one progresses follow me a row or tower of the regular table that elements. The atom radius is one such characteristic that trends across a duration and down a group of the regular table.


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Periodic trends: A graphic showing as whole periodic trends in the regular table.


Meaning the the atomic Radius

The atomic radius the a chemical aspect is a measure of the size of the atoms, typically the average or common distance native the nucleus come the boundary of the neighboring cloud of electrons. Due to the fact that the boundary is not a well-defined physical entity, there are miscellaneous non-equivalent meanings of atomic radius.

Depending on context, the term atomic radius may apply only come isolated atoms, or also to atom in condensed matter, covalently bound in molecules, or in ionized and excited states. The value of an atomic radius may be derived through experimental measurements or computed through theoretical models. Under part definitions, the value of a radius may depend ~ above the atom’s state and context. For our purposes, us are normally looking at atom in your elemental state.


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


Atomic radii differ in a predictable and explicable manner throughout the routine table. Radii typically decrease indigenous left to right along each period (row) of the table, indigenous the alkali steels to the noble gases; radii boost down each group (column). The radius boosts sharply in between the noble gas at the finish of each period and the alkali metal at the beginning of the following period. These patterns of the atomic radii (and of various other chemical and physical properties of the elements) can be defined by the electron shell theory of the atom. Radii measurements noted important proof for the advancement and confirmation of quantum theory.

Explanation that the basic Trends

The way atomic radius varies with increasing atomic number have the right to be described by the arrangement of electrons in shells of fixed capacity. Shells closer to the nucleus—those v a smaller radius—are normally filled first, due to the fact that the negatively charged electrons are attracted through the positively charged proton in the nucleus. As the atomic number boosts along a heat of the regular table, extr electrons are included to the same, outermost shell. The radius that this shell slowly contracts as the attraction in between the additional electrons and the nucleus increases. In a noble gas, the outermost covering is totally filled. Therefore, the additional electron of following alkali metal (one row down on the periodic table) will go into a brand-new outer shell, audit for the sudden boost in the atom radius.


Atomic number come radius graph: A chart showing the atom radius family member to the atomic number of the elements.


The boosting nuclear fee is partly counterbalanced by the increasing variety of electrons, a phenomenon that is well-known as shielding; this explains why the dimension of atom usually increases down each column. Underlying causes of the periodic trends in atomic radius also have an affect on various other chemical and also physical properties of the elements.


Ionic Radius

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


Key Takeaways

Key PointsThe ionic radius is the distance in between the nucleus and the electron in the outermost covering of one ion.When one atom loser an electron to kind a cation, the shed electron no longer contributes come shielding the various other electrons indigenous the fee of the nucleus; consequently, the various other electrons are more strongly attracted to the nucleus, and also the radius of the atom it s okay smaller.When one electron is added to an atom, creating an anion, the added electron repels other electrons, result in rise in the dimension of the atom.The tendency observed in dimension of ionic radii is due to shielding of the outermost electron by the inner-shell electron so the the external shell electrons carry out not “feel” the entire positive charge of the nucleus.Key Termscation: A positively fee ion, as opposed come an anion.ion: an atom or group of atoms bearing an electrical charge, such together the sodium and chlorine atoms in a salt solution.anion: A negatively charged ion, together opposed to a cation.

In chemistry, periodic trends are the tendencies of specific elemental qualities to increase or decrease along a period (row) or team (column) of the routine table that elements. Ionic radius (rion) is the radius of an ion, nevertheless of whether it is one anion or a cation. Although neither atoms nor ions have actually sharp boundaries, that is helpful to treat them together if lock are tough spheres through radii. In this way, the sum of ionic radii that a cation and an anion can provide us the distance between the ions in a crystal lattice. Ionic radii are commonly given in devices of either picometers (pm) or Angstroms (Å), through 1 Å = 100 pm. Typical values range from 30 afternoon (0.3 Å) to end 200 pm (2 Å).

Trends in Ionic Radii

Ions may be bigger or smaller than the neutral atom, depending upon the ion’s charge. Once an atom loses an electron to kind a cation, the lost electron no longer contributes come shielding the other electrons indigenous the charge of the nucleus; consequently, the various other electrons are more strongly attractive to the nucleus, and also the radius the the atom gets smaller. Similarly, once an electron is included to an atom, creating an anion, the included electron repels various other electrons, result in boost in the size of the atom.

The ionic radius is no a fixed building of a offered ion; rather, it varies through coordination number, rotate state, and also other parameters. Because that our purposes, we are considering the ions to be as close to their ground state together possible. Nevertheless, ionic radius values are sufficiently transferable to permit periodic fads to be recognized.


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


As through other species of atomic radii, ionic radii rise upon to decrease a group and also decrease going throughout a period. Keep in mind that this only applies if the elements are the same form of ion, one of two people cations or anions. For example, while neutral lithium is bigger than neutral fluorine, the lithium cation is lot smaller than the fluorine anion, because of the lithium cation having a different highest power shell.


Ionization Energy

The ionization power tends to increase as one moves from left to right throughout a given period or increase a group in the regular table.


Key Takeaways

Key PointsThe ionization power is the power required to eliminate an electron native its orbital approximately an atom to a suggest where that is no longer linked with the atom.The ionization energy of an element increases as one moves throughout a period in the routine table because the electrons are hosted tighter by the greater effective nuclear charge.The ionization power of the elements increases as one move up a given group since the electron are hosted in lower-energy orbitals, closer to the nucleus and therefore are more tightly tied (harder to remove).Key Termsionization energy: The power needed to eliminate an electron indigenous an atom or molecule come infinity.

Periodic fads in the Ionization Energy

The ionization energy of a chemical varieties (i.e., an atom or molecule ) is the power required to eliminate electrons indigenous gaseous atom or ions. This residential property is also referred to as the ionization potentia and is measure up in volts. In chemistry, it regularly refers come one mole of a problem (molar ionization power or enthalpy) and also is report in kJ/mol. In atomic physics, the ionization power is frequently measured in the unit electron volt (eV). Big atoms or molecules have actually low ionization energy, while little molecules tend to have greater ionization energies.

The ionization energy is various for electrons of different atomic or molecule orbitals. Much more generally, the nth ionization energy is the energy required to strip off the nth electron after the very first n-1 electrons have been removed. That is taken into consideration a measure of the tendency of one atom or ion come surrender an electron or the toughness of the electron binding. The higher the ionization energy, the more complicated it is to remove an electron. The ionization energy may be an indicator of the reactivity of one element. Aspects with a short ionization energy tend to be reducing agents and type cations, which in turn integrate with anions to kind salts.


Ionization energy: This graph mirrors the an initial ionization power of the elements in electron volts.


Moving left to best within a period or upward within a group, the first ionization power generally increases. As the atomic radius decreases, it i do not care harder to remove an electron the is closer to a an ext positively fee nucleus. Conversely, as one progresses down a group on the routine table, the ionization energy will likely decrease because the valence electrons are farther away from the nucleus and experience higher shielding. They experience a weaker attraction to the confident charge that the nucleus. Ionization energy increases native left to best in a duration and reduce from peak to bottom in a group.

Rationale for the regular Trends in Ionization Energy

The ionization power of an aspect increases as one moves throughout a duration in the periodic table because the electrons are organized tighter by the higher effective atom charge. This is because added electrons in the same shell do not substantially add to shielding each various other from the nucleus, however boost in atomic number coincides to rise in the variety of protons in the nucleus.

The ionization power of the facets increases together one moves up a provided group due to the fact that the electron are held in lower-energy orbitals, closer to the nucleus and also thus more tightly bound (harder come remove).

Based top top these 2 principles, the easiest aspect 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 particle to acquire an electron. This is one exothermic procedure for all non-noble gas elements.There are basic trends in electron affinity across and under the regular table the elements. Electron affinity usually increases throughout a period in the regular table and sometimes decreases down a group.These trends space not necessarily universal.The chemical rationale for alters in electron affinity across the periodic table is the increased efficient nuclear charge across a duration and up a group.Key Termselectron affinity: The electron affinity of an atom or molecule is defined as the amount of energy released as soon as an electron is added to a neutral atom or molecule to form a negative ion.electronegativity: The propensity of an atom or molecule to attract electrons come itself.

The electron affinity (Eea) the a neutral atom or molecule is characterized as the quantity of energy released as soon as an electron is included to the to type a an unfavorable ion, as demonstrated through the adhering to equation:

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

Electron affinity is measured because that atoms and molecules in the gaseous state only, because in the heavy or liquid says their power levels would certainly be changed by contact with other atoms or molecules. Robert S. Mulliken used a perform of electron six to develop an electronegativity range for atoms by finding the mean of the electron affinity and ionization potential. A molecule or atom that has actually a an ext positive electron affinity value is often dubbed an electron acceptor; one with a less positive electron affinity is called an electron donor. With each other they may undergo charge-transfer reactions.

To use electron six properly, the is essential to save track of the sign. For any reaction the releases energy, the change in power (ΔE) has actually a an adverse value, and also the reaction is dubbed an exothermic process. Electron record for nearly all non-noble gas atoms entails the relax of energy and therefore is an exothermic process.


Confusion may arise in mistaking Eea for ΔE. The numbers listed in tables the Eea room all positive because they room magnitudes; the worths of Eea in a table that electron six all show the lot of power released once an electron is added to an element. Because the release of power is constantly an exothermic event, these every correspond to an unfavorable values that ΔE (indicating an exothermic process).

Periodic fads in Electron Affinity

Although Eea varies greatly across the routine table, some fads emerge. Generally, nonmetals have an ext positive Eea 보다 metals. Atoms, such as group 7 elements, who anions are much more stable 보다 neutral atoms have actually a higher Eea. The electron affinities of the noble gases have actually not been conclusively measured, for this reason they may or might not have actually slightly negative values. Chlorine has the highest Eea while mercury has the lowest.

Eea typically increases throughout a period (row) in the routine table, due to the filling of the valence shell of the atom. For instance, in ~ the exact same period, a Group-17 atom releases much more energy than a Group-1 atom upon gaining an electron because the included electron create a to fill valence shell and therefore is more stable.

A tendency of diminish Eea down the groups in the periodic table would be expected, because the added electron is beginning an orbit farther away from the nucleus. Since this electron is aside from that away, it have to be less attracted come the nucleus and also release less energy when added. However, this trend applies only come Group-1 atoms. Electron affinity complies with the tendency of electronegativity: fluorine (F) has actually a greater electron affinity 보다 oxygen (O), and so on.

The trends detailed here space very comparable to those in ionization power and adjust for similar (though opposing) reasons.

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