Name: chemical bonding and bond properties
Uploaded: 2020-09-03T13:38:28.000Z
Duration: 2 min 37 s
Channel: JoVE

K12 Standards

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

NC K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.3.1

Types of Chemical Bonds

As ligações químicas são essenciais para os átomos poderem formar uma variedade de compostos, tais como sal, água ou misturas. Compreender a formação das ligações químicas, ou mais especificamente a atração entre os átomos, ajudará a compreender e a prever o comportamento molecular. O núcleo de um átomo é constituído por nêutrons e protões com carga positiva, que estão rodeados por elétrons com carga negativa.Quando dois átomos se aproximam um do outro, os elétrons de um átomo são atraídos para o núcleo do outro átomo e vice-versa. Simultaneamente, os núcleos de ambos os átomos repelem-se mutuamente, tal como os elétrons de cada átomo. Quando estas interações levam a uma redução líquida da energia potencial, forma-se uma ligação química.Existem três tipos de ligações químicas. Um metal e um não-metal, como o sódio e o cloro, formam uma ligação iónica. Os metais têm baixas energias de ionização permitindo uma remoção mais fácil de elétrons do átomo.Estes elétrons são prontamente aceites por não metais, dadas as suas altas afinidades com os elétrons e a ânsia de conseguir uma camada de valência completa. Portanto, o metal transfere elétrons para o não-metal formando um cátion e um ânion. Estas partículas carregadas atraem-se umas às outras para criar uma ligação iónica.O segundo tipo é o das ligações covalentes formadas entre dois não metálicos, como um átomo de carbono e dois átomos de oxigénio que formam dióxido de carbono. Os não-metálicos têm elevadas energias de ionização tornando difícil a remoção e a transferência de elétrons de valência de um átomo para outro, daí que os elétrons sejam partilhados entre os átomos. Estes elétrons partilhados interagem com ambos os núcleos dos átomos de ligação e baixam a energia potencial.O último tipo é a ligação metálica formada entre dois átomos de metal. Os átomos metálicos perdem facilmente os elétrons de valência, formando um polo de elétrons de acordo com o modelo mais simples do mar de elétrons. Os elétrons de valência são deslocalizados sobre todo o metal e os átomos de metal com carga positiva são atraídos por este pólo de elétrons que mantém os átomos juntos.

tipos de ligações químicas

As teorias de ligações químicas foram pioneiras pelo químico Americano Gilbert N. Lewis. Ele desenvolveu um modelo chamado o modelo Lewis para explicar o tipo e formação de diferentes ligações. As ligações químicas são centrais para a química; explicam como os átomos ou iões se unem para formar moléculas. Explicam porque algumas ligações são fortes e outras são fracas, ou porque um carbono se liga a dois oxigénios e não três; porque a água é H2O e não H4O. 

<h4>Ligações Iónicas</h4>

Iões são átomos ou moléculas que contêm uma carga eléctrica. Um catião (um ião positivo) forma-se quando um átomo neutro perde um ou mais eletrões da sua camada de valência e um anião (um ião negativo) forma-se quando um átomo neutro ganha um ou mais eletrões na sua camada de valência. Os compostos constituídos por iões são chamados compostos iónicos (ou sais), e os iões que os constituem são mantidos em conjunto por ligações iónicas: forças eletrostáticas de atração entre catiões e aniões opostamente carregados.

As propriedades dos compostos iónicos forneceram alguma luz relativamente à natureza das ligações iónicas. Os sólidos iónicos apresentam uma estrutura cristalina e tendem a ser rígidos e quebradiços; eles também tendem a ter pontos de fusão e ebulição altos, o que sugere que as ligações iónicas são muito fortes. Os sólidos iónicos são também condutores pobres de electricidade pela mesma razão—a força das ligações iónicas impede que iões se movam livremente no estado sólido. No entanto, a maioria dos sólidos iónicos dissolve-se rapidamente em água. Uma vez dissolvidos ou derretidos, os compostos iónicos são excelentes condutores de eletricidade e calor, pois os iões podem mover-se livremente.

<h4>Ligações Covalentes</h4>

Átomos não metálicos formam frequentemente ligações covalentes com outros átomos não metálicos. As ligações covalentes formam-se quando os eletrões são partilhados entre átomos e são atraídos pelos núcleos de ambos os átomos. Se os átomos que formam uma ligação covalente forem idênticos, como em H2, Cl2, e outras moléculas diatómicas, então os eletrões na ligação devem ser partilhados igualmente. Isto é referido como uma ligação covalente pura. Quando os átomos ligados por uma ligação covalente são diferentes, os eletrões de ligação são partilhados, mas já não são iguais. Em vez disso, os eletrões de ligação são mais atraídos por um átomo do que pelo outro, dando origem a uma mudança da densidade de eletrões em direção a esse átomo. Esta distribuição desigual de eletrões é conhecida como uma ligação covalente polar.

Os compostos que contêm ligações covalentes apresentam propriedades físicas diferentes das dos compostos iónicos. Como a atração entre moléculas, que são eletricamente neutras, é mais fraca do que entre iões eletricamente carregados, os compostos covalentes geralmente têm pontos de fusão e ebulição muito mais baixos do que os compostos iónicos. Além disso, embora os compostos iónicos sejam bons condutores de eletricidade quando dissolvidos em água, a maioria dos compostos covalentes é insolúvel em água; uma vez que são neutros em termos elétricos, são pobres condutores de eletricidade em qualquer estado.

<h4>Ligações Metálicas</h4>

As ligações metálicas são formadas entre dois átomos de metal. Um modelo simplificado para descrever a ligação metálica foi desenvolvido por Paul Drüde, denominado 'Modelo de Mar de Eletrões'. Com base nas baixas energias de ionização dos metais, o modelo afirma que os átomos de metal perdem os seus eletrões de valência facilmente e tornam-se catiões. Estes eletrões de valência criam um conjunto de eletrões desocalizados em torno dos catiões sobre todo o metal. 

Sólidos metálicos, como cristais de cobre, alumínio, e ferro, são formados por átomos de metal, e todos apresentam alta condutividade térmica e elétrica, lustre metálico, e maleabilidade. Muitos são muito duros e bastante fortes. Devido à sua maleabilidade (capacidade de deformação sob pressão ou marteladas), não se estilhaçam e, portanto, constituem materiais de construção úteis. Os pontos de fusão dos metais variam muito. O mercúrio é um líquido à temperatura ambiente, e os metais alcalinos derretem abaixo de 200 °C. Vários metais de pós-transição também têm pontos de fusão baixos, enquanto que os metais de transição derretem a temperaturas acima de 1000 °C. Essas diferenças refletem diferenças na resistência das ligações metálicas entre os metais. 

Este texto é adaptado de <a href="https://openstax.org/books/chemistry-2e/pages/7-1-ionic-bonding">Openstax, Chemistry 2e, Section 7.1: Ionic Bonding</a>, <a href="https://openstax.org/books/chemistry-2e/pages/7-2-covalent-bonding">Openstax, Chemistry 2e, Section 7.2: Covalent Bonding</a>, e <big><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>.</big>

Tipos de Ligações Químicas

As teorias de ligações químicas foram iniciadas pelo químico americano Gilbert N. Lewis. Ele desenvolveu um modelo chamado modelo de Lewis para explicar o tipo e ...

Education

JoVE Core

Química

Chemical Bonding: Basic Concepts

Ligações Químicas: Conceitos Básicos

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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 shell. An anion is a negative ion formed when a neutral atom gains one or more electrons in its valence shell. Ionic compounds, also called salts, are held together by electrostatic attraction between oppositely charged cations and anions.

The properties of ionic compounds show why ionic bonds are strong. Ionic solids usually have a crystalline structure and are rigid and brittle. They also tend to have high melting and boiling points. In the solid state, they are poor conductors of electricity because the ions cannot move freely. Many ionic solids dissolve readily in water. When they are dissolved or melted, they conduct electricity and heat well because the ions can move about freely.

Covalent bonding is common between nonmetal atoms. It forms when atoms share electrons, and the shared electrons are attracted by the nuclei of both atoms. When identical atoms bond, as in H2 and Cl2, the electrons are shared equally. This is called a pure covalent bond. When different atoms bond, the electrons are still shared, but not equally. This creates a polar covalent bond, where electron density shifts toward one atom.

Covalent compounds have different properties from ionic compounds. Because the attraction between neutral molecules is weaker than the attraction between charged ions, covalent compounds usually have much lower melting and boiling points. Most are insoluble in water. They are also poor conductors of electricity in any state because they are electrically neutral.

Metallic bonding forms between metal atoms. Paul Drude's electron sea model describes this bond by saying that metal atoms lose valence electrons easily and become cations. The valence electrons form a pool of delocalized electrons around the cations throughout the metal. Metallic solids, such as copper, aluminum, and iron, conduct heat and electricity well. They also have metallic luster and are malleable, so they can deform under pressure or hammering without shattering.

Metals can have very different melting points. Mercury is liquid at room temperature, and alkali metals melt below 200 degrees Celsius. Several post-transition metals also have low melting points. Transition metals, however, melt above 1000 degrees Celsius. These differences reflect differences in the strength of metallic bonding among metals.

Chemical Bonding and Bond Properties

types of chemical bonds

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

How Bond Energy Predicts Reaction Heat

Bond energy helps explain why molecules stay together and how much heat a reaction may release or absorb. A covalent bond is stronger when more energy is needed to separate the atoms. The energy needed to break one specific covalent bond in one mole of gaseous molecules is called bond energy, or bond dissociation energy. For a diatomic molecule, bond energy is the standard enthalpy change for an endothermic reaction that breaks that bond. The H-H bond is a common example. Its bond energy is...

bonding in metals

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...

key terms and concepts

Explore ionic, covalent, and metallic bonding, plus the properties of each. Learn how electrons, ions, and metals explain structure, conductivity, and melting points.

Chemical Bonding and Bond Properties | JoVE K12

chemistry

JoVE Core - Química dá vida a conceitos gerais de química usando vídeos de animação fáceis de entender. Além disso, nos vídeos Cientistas em ação, demonstramos experimentos de pesquisa clássicos e originais realizados atualmente por cientistas em laboratórios em todo o mundo.

Physical Science

PS.PSc.2.1

ohios-learning-standards-and-model-curriculum

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)

Tennessee Academic Standards

High School

Matter and Its Interactions

CHEM1.PS1.14

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

CHEM1.PS2.1

CHEM1.PS2.2

Virginia  Standards of Learning

HIgh School

CH.3

CH.3.d

PS.3

PS.3.c

Minnesota Academic Standards in Science

1.2.1 9C.1.2.1.2

Arizona Science Standards

HS.P1

HS.P1U1.2

HS+C.P1

HS+C.P1U1.4

Texas Essential Knowledge and Skills

CHEM.6

CHEM.6.E

Alabama Course of Study Science

9-12.C.2.2.a

9-12.C.2.2.c

Florida Department of Education

SC.912.P.8

SC.912.P.8.6

Chemistry and Physics

IPC.7

IPC.7.A

new-york-state-science-learning-standards

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

SPS2.

Chemical Bonds

SC2.

bonding-types-from-nonpolar-covalent-to-ionic

Bonding Types: From Nonpolar Covalent to Ionic

Scientific Laws and Theories

Scientific Laws

In science, a law is defined as a concise, verbal or mathematical, statement that summarizes a vast number of experimental observations. ...

The Scientific Method

Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To ...

Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

Classifying Matter by Composition

Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories &mdash; pure substances and ...

The Atomic Theory of Matter

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

Subatomic Particles

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

Elements: Chemical Symbols and Isotopes

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

Use models to explain how the scientific understanding of atomic structure has evolved.

PS.Chm.1.1

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger ...

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Use models to compare nuclear reactions including alpha decay, beta decay and gamma decay; nuclear fusion and nuclear fission.

PS.Chm.1.2

Atomic Orbitals

An atomic orbital represents the three-dimensional regions in an atom where an electron has the highest probability to reside. The radial distribution ...

The Pauli Exclusion Principle

The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that ...

The Energies of Atomic Orbitals

In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are ...

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and ...

electron-configuration-of-multielectron-atoms

Electron Configuration of Multielectron Atoms

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the ...

Use models to explain how electrons are distributed in atoms.

PS.Chm.1.3

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 ...

The Periodic Table

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

Atomic Mass

Atoms &mdash; and the protons, neutrons, and electrons that compose them &mdash; are extremely small. For example, a carbon atom weighs less than 2 ...

Molar Mass

The identity of a substance is defined not only by the types of atoms or ions it contains but by the quantity of each type of atom or ion. For example, ...

Use the Periodic Table as a model to predict the relative properties of elements based on the pattern of valence electrons in the outermost energy levels of atoms.

PS.Chm.2.1

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 ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

Construct an explanation to infer the atomic size, reactivity, electronegativity, and ionization energy of an element based on its position in the Periodic Table.

PS.Chm.2.2

Analyze the structure of atoms and isotopes.

Chemical Bonding and Bond Properties

Description

Transcript

Tags

More videos by Standards