Name: electron sea model in metals
Uploaded: 2020-09-03T13:38:28.000Z
Duration: 2 min 32 s
Channel: JoVE

K12 Standards

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

North Carolina K-12 Science Standard Course of Study

9-12

Physical Science

Matter and its Interactions

PS.PSc.2.1

Bonding in Metals

Un legame metallico è un legame fra due atomi di metallo. Rispetto ai non metalli, i metalli hanno basse energie di ionizzazione, consentendo loro di perdere facilmente gli elettroni di valenza. Questo conferisce al legame metallico proprietà distinte in contrasto con i legami ionici e covalenti.

I legami metallici e la maggior parte delle loro proprietà possono essere spiegati utilizzando il semplice modello del mare di elettroni. Considerate il metallo potassio. Grazie alla bassa energia di ionizzazione, ogni atomo di potassio può facilmente perdere il suo elettrone di valenza per diventare un catione.

Questi cationi di potassio sono tenuti insieme strettamente grazie alla loro attrazione per il mare di elettroni, caricati negativamente. Gli elettroni non sono limitati a un singolo ione ma sono distribuiti uniformemente e relativamente liberi di muoversi all'interno del metallo. Il modello del mare di elettroni tiene conto di diverse importanti caratteristiche dei metalli.

Per esempio, quando una differenza di tensione viene applicata a un filo metallico, come un filo di rame, gli elettroni caricati negativamente si muovono liberamente verso l'estremità positiva del filo, generando una corrente elettrica. Questo è il motivo per cui la maggior parte dei metalli sono eccellenti conduttori di elettricità. Al contrario, i composti ionici non sono conduttori di elettricità nella loro forma solida, ma possono condurre elettricità quando disciolti in acqua.

Questo perché, in un legame ionico cristallino, gli elettroni vengono trasferiti dal metallo al non metallo, ma rimangono localizzati in uno ione. Tuttavia, una volta disciolti in acqua, i cationi e gli anioni si dissociano e possono muoversi se sottoposti a una differenza di potenziale, creando una corrente elettrica. I metalli sono anche ottimi conduttori termici.

Secondo il modello del mare degli elettroni, quando il calore viene applicato a un'estremità del metallo, gli elettroni si muovono liberamente e disperdono rapidamente il calore attraverso il metallo. I metalli possono essere facilmente spianati in fogli grazie alla loro malleabilità o in fili grazie alla proprietà di duttilità. Poiché non ci sono legami localizzati nei metalli, gli atomi di metallo possono scorrere l'uno sull'altro consentendo una facile deformità.

Gli elettroni quindi fluiscono nella nuova forma per accogliere la deformità.

legame nei metalli

I legami metallici si formano tra due atomi di metallo. Un modello semplificato per descrivere il legame metallico stato sviluppato da Paul Drde chiamato “modello del mare di elettroni?.

Modello del mare di elettroni

La maggior parte degli atomi metallici non possiede abbastanza elettroni di valenza per formare un legame ionico o covalente. Tuttavia, gli elettroni di valenza negli atomi metallici sono trattenuti in modo debole a causa della loro bassa elettronegativit o attrazione con il nucleo. L'energia di ionizzazione degli atomi metallici (energia richiesta per rimuovere un elettrone dall'atomo) bassa, facilitando la facile rimozione degli elettroni di valenza dall'atomo genitore. L'atomo forma uno ione metallico caricato positivamente, mentre gli elettroni esterni liberi esistono come nuvole di elettroni delocalizzati caricati negativamente. Questi elettroni possono essere condivisi da pi cationi metallici vicini attraverso una forte forza attrattiva tra queste specie caricate negativamente e positivamente. Una tale forza attrattiva tra gli elettroni caricati negativamente e i cationi metallici chiamata legami metallici, che tengono insieme gli atomi. Questo modello del mare di elettroni spiega la maggior parte delle propriet fisiche dei metalli come conduttanza al calore e all’elettricit, punti di fusione e di ebollizione elevati, malleabilit e duttilit.

Solidi metallici

Il modello del mare di elettroni tiene conto di diverse propriet metalliche, tra cui elevata conduttivit termica ed elettrica, lucentezza metallica, duttilit e malleabilit. Gli elettroni delocalizzati possono condurre sia l'elettricit che il calore da un'estremit all'altra del metallo con bassa resistenza. Il legame metallico non tra due atomi metallici specifici, ma tra ioni metallici e molti elettroni delocalizzati, consentendo ai metalli di deformarsi sotto pressione e calore senza frantumarsi o rompersi. Metalli diversi, come ferro, mercurio o rame, differiscono nelle loro propriet fisiche, riflettendo la differenza nella forza del legame metallico tra i metalli.

I solidi metallici come i cristalli di rame, alluminio e ferro sono formati da atomi di metallo: tutti presentano un'elevata conduttivit termica ed elettrica, lucentezza metallica e malleabilit. Molti sono molto duri e piuttosto forti. A causa della loro malleabilit (la capacit di deformarsi sotto pressione o martellamento), non si frantumano e, quindi, costituiscono utili materiali da costruzione. I punti di fusione dei metalli variano ampiamente. Il mercurio un liquido a temperatura ambiente e i metalli alcalini fondono al di sotto dei 200 °C. Anche diversi metalli post-transizione hanno punti di fusione bassi, mentre i metalli di transizione fondono a temperature superiori a 1000 °C. Queste differenze riflettono le differenze nella forza del legame metallico tra i metalli.

Questo testo adattato da <a href="https://openstax.org/books/chemistry-2e/pages/10-5-the-solid-state-of-matter">Openstax, Chemistry 2e, Section 10.5: The Solid State of Matter.</a>

Legame nei metalli

I legami metallici si formano tra due atomi di metallo. Un modello semplificato per descrivere l'incollaggio metallico è stato sviluppato da Paul Drüde chiamato ...

Education

Didattica

JoVE Core

Chemistry

Chimica

Chemical Bonding: Basic Concepts

Legami chimici: concetti fondamentali

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

electron sea model in metals

Electron sea model explains how metallic bonding holds metals together. In this model, most metal atoms do not have enough valence electrons to form ionic or covalent bonds in the usual way. Their valence electrons are held loosely because metals have low electronegativity, and their ionization energy is low, so electrons are removed easily.

When a metal atom loses these outer electrons, it becomes a positively charged metal ion. The freed electrons form a delocalized electron cloud around many neighboring metal cations. Metallic bonds are the attractive forces between the negative electrons and the positive ions. These bonds do not link just two atoms. They connect metal ions to many shared electrons throughout the solid.

This electron sea model helps explain the main properties of metallic solids. Delocalized electrons carry heat and electricity with low resistance, so metals are good conductors. Metals also have metallic luster, high melting and boiling points, ductility, and malleability. Because the bonding is spread through the structure, metals can deform under pressure or heat without shattering or breaking.

Different metals can have different physical properties because their metallic bond strength is not the same. Examples of metallic solids include copper, aluminum, and iron crystals, and all show high thermal and electrical conductivity, luster, and malleability. Many metals are very hard and strong, which makes them useful as construction materials. Their melting points also vary widely. Mercury is liquid at room temperature, alkali metals melt below 200 °C, several post-transition metals melt at low temperatures, and transition metals often melt above 1000 °C. These differences reflect changes in metallic bonding strength.

Electron Sea Model in Metals

types of chemical bonds

Chemical Bonding and Bond Properties

Chemical bonding explains how atoms and ions join to form molecules and compounds. American chemist Gilbert N. Lewis pioneered chemical bonding theory with the Lewis model. This model helps explain why bonds form, why some are stronger than others, and why compounds have fixed formulas like H2O instead of H4O. Ionic bonding involves ions, which are atoms or molecules with an electrical charge. A cation is a positive ion formed when a neutral atom loses one or more electrons from its valence...

the born-haber cycle

Predicting Ionic Stability with Lattice Energy

Lattice energy helps explain why ionic compounds are stable. It measures the strength of attraction between positive and negative ions in a crystal. In one common definition, lattice energy is the energy required to separate one mole of an ionic solid into gaseous ions, so it has a positive value. Another definition uses the opposite sign and describes the energy released when gaseous ions form a lattice. When checking data, it is important to confirm which convention is being used. In either...

lewis symbols and the octet rule

Valence Electrons, Lewis Symbols, and Bonding

Chemical bonds form when atoms or ions interact in ways that lower the potential energy of a molecule. Gilbert N. Lewis created a simple model to show bond formation using valence electrons, the electrons in the outer shell. In this model, electrons are shared or transferred to help atoms reach a stable electron configuration. The Lewis model helps describe two common bond types. An ionic bond forms when electrons move from a metal to a nonmetal. A covalent bond forms when two nonmetals share...

electronegativity

Electronegativity and Polar Bonds

Electronegativity helps explain why some covalent bonds are nonpolar and others are polar covalent. It is a measure of how strongly an atom attracts shared electrons toward itself. That pull controls how electron density is distributed in a bond. Linus Pauling proposed the first electronegativity values by studying bond energies in heteronuclear molecules such as hydrogen fluoride. He expected the bond energy of HF to be about the average of the bond energies of H2 and F2, or 296 kJ/mol. The...

ionic bonding and electron transfer

Ionic Compounds and Crystal Lattices

Ionic compounds form when positive and negative ions attract each other. A cation is a positive ion, and it forms when an atom loses one or more valence electrons. An anion is a negative ion, and it forms when an atom gains one or more valence electrons. Compounds made of these ions are called ionic compounds, or salts, and the force between them is an ionic bond. The properties of ionic solids help show how strong this attraction is. They usually form rigid, brittle crystals and have high...

trends in lattice energy: ion size and charge

trends-in-lattice-energy-ion-size-and-charge

Lattice Energy Patterns in Ionic Solids

Lattice energy shows how strongly ions hold an ionic solid together. It is the energy required to separate one mole of a solid into its gaseous ions. For sodium chloride, this process requires 769 kJ per mole. The opposite convention may also be used, where lattice energy is the energy released when gaseous ions form the solid. In either case, a larger magnitude means a more stable ionic compound. For ionic crystals, lattice energy follows a pattern based on charge and ion size. The...

covalent bonding and lewis structures

Shared Electrons in Covalent Molecules

Covalent molecules form when atoms share electrons instead of transferring them. This bonding usually happens between nonmetal atoms with similar tendencies to attract electrons. Because the atoms pull on the electrons in a shared way, the bond is held together by mutual attraction. Covalent compounds often have physical properties that differ from ionic compounds. The attraction between neutral molecules is weaker than the attraction between charged ions. As a result, many covalent compounds...

bond polarity, dipole moment, and percent ionic character

bond-polarity-dipole-moment-and-percent-ionic-character

How Bond Polarity Shapes Molecular Dipoles

Bond polarity depends on electronegativity, the ability of an atom to attract shared electrons. The absolute value of the electronegativity difference, or ΔEN, gives a rough guide to bond type. When the difference is very small or zero, the bond is covalent and nonpolar. When it is larger, the bond may be polar covalent or ionic. Examples show how this works in real compounds. H–H has a ΔEN of 0, so it is nonpolar. H–Cl has a ΔEN of 0.9, so it is polar covalent. Na–Cl has a ΔEN of 2.1, so it...

lewis structures of molecular compounds and polyatomic ions

lewis-structures-of-molecular-compounds-and-polyatomic-ions

Drawing Lewis Structures with Valence Electron Counts

Drawing Lewis structures starts with counting valence electrons and building the atom arrangement step by step. Valence electrons are the outer-shell electrons that help show how atoms bond. For ions, a positive charge means one electron is removed for each plus sign, and a negative charge means one electron is added for each minus sign. The next step is to sketch the skeleton structure. The least electronegative atom usually goes in the center, while hydrogen is almost never central. Fluorine...

resonance

Resonance Forms in Lewis Structures

Resonance forms in Lewis structures help explain molecules and ions that cannot be shown correctly with just one drawing. In nitrite ion, NO2−, the Lewis structure can be drawn in two ways. The N-O and N=O bonds switch positions in the two drawings, but the atoms stay in the same arrangement. If nitrite really had one single bond and one double bond, the two bond lengths should be different. A double bond is shorter and stronger than a single bond between the same atoms. Experiments show that...

formal charges

Lewis Structures with Formal Charge

Lewis structures can sometimes show more than one reasonable arrangement for a molecule or polyatomic ion. Formal charge helps chemists choose the best Lewis structure when that happens. It is a useful way to compare possible structures in chemistry. Formal charge is the hypothetical charge an atom would have if bonding electrons were shared evenly between the atoms. It can also be found by starting with the valence electrons of the neutral atom, subtracting the nonbonding electrons, and then...

exceptions to the octet rule

Octet Rule Exceptions in Lewis Structures

Some covalent molecules do not follow the octet rule in their Lewis structures. Their central atoms can fall into three groups: odd-electron molecules, electron-deficient molecules, and hypervalent molecules. These cases show why a Lewis structure may not always give every atom eight valence electrons. Odd-electron molecules have an odd number of valence electrons, so one electron remains unpaired. Molecules with an odd number of electrons are called radicals. Nitric oxide, NO, is one example,...

bond energies and bond lengths

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bonding in metals

Electron sea model explains how metallic bonding holds metals together. In this model, most metal atoms do not have enough valence electrons to form ionic or covalent bonds in the usual way. Their valence electrons are held loosely because metals have low electronegativity, and their ionization energy is low, so electrons are removed easily. When a metal atom loses these outer electrons, it becomes a positively charged metal ion. The freed electrons form a delocalized electron cloud around...

key terms and concepts

Learn how the electron sea model explains metallic bonding, conductivity, malleability, luster, and why metals like mercury, copper, and iron differ.

Electron Sea Model in Metals | JoVE K12

chemistry

JoVE Core: Chimica illustra concetti chiave di chimica attraverso video animazioni concise e di immediata comprensione. Inoltre, i video della sezione "scienziati in azione" mostrano procedure metodologiche realizzate da ricercatori provenienti dai migliori laboratori internazionali.

Pennsylvania State Academic Standards

Structure and Properties of Matter

3.2.9-12.B

3.2.9-12.N

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Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Bonding and compounds

Structure And Properties Of Matter

Chemical bonding

Physical Geology

Minerals

Chemical bonding (ionic, covalent, metallic)

Virginia  Standards of Learning

HIgh School

CH.3

CH.3.d

Physics

PH.9

PH.9.e

Arizona Science Standards

High School

HS.P1

HS.P1U1.2

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New Jersey Student Learning Standards for Science

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Motion and Stability: Forces and Interactions

HS-PS2-6

Alabama Course of Study Science

9-12.C.2.2.c

Next Generation Science Standards

Matter and Its Interactions

HS-PS1-4

Florida Department of Education

SC.912.P.8

SC.912.P.8.6

Texas Essential Knowledge and Skills

Chemistry and Physics

IPC.7

IPC.7.A

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New York State Science Learning Standards

HS. Structure and Properties of Matter

HS-PS1-3.

HS. Chemical Reactions

HS-PS1-2.

HS-PS1-4.

HS-PS1-12.

Georgia Standards of Excellence

SC2.

Molecular Structures in Material Design

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
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Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Molecules and Compounds

Atoms and Molecules

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

Solution Formation

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

Colloids

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

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

PS.PSc.1.1

Phase Transitions

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

phase-transitions-vaporization-and-condensation

Phase Transitions: Vaporization and Condensation

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

Vapor Pressure

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

Clausius-Clapeyron Equation

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

Phase Transitions: Melting and Freezing

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

phase-transitions-sublimation-and-deposition

Phase Transitions: Sublimation and Deposition

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

Heating and Cooling Curves

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

Phase Diagrams

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

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

PS.PSc.1.2

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Physical and Chemical Properties of Matter

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

Physical Properties of Matter

A physical property is ...

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

Molecular Comparison of Gases, Liquids, and Solids

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

Intermolecular vs Intramolecular Forces

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

Intermolecular Forces

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

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

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

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

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

PS.PSc.1.3

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

The Bohr Model

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

Emission Spectra

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

The de Broglie Wavelength

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

The Uncertainty Principle

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

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

PS.PSc.1.4

Ions and Ionic Charges

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

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

PS.PSc.1.5

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

atomic-radii-and-effective-nuclear-charge

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 ...

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

PS.PSc.1.6

Understand types, properties, and structure of matter.

Electron Sea Model in Metals

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