Name: atomic elements, molecules, and bonds
Uploaded: 2020-09-03T13:38:25.000Z
Duration: 2 min 38 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.3.3

Molecules and Compounds

Na natureza, toda a matéria é composta por unidades químicas básicas denominadas de elementos e que têm propriedades físicas e químicas específicas. A tabela periódica enumera um total de 118 elementos identificados até à data. A unidade constituinte de cada elemento é o átomo.Alguns elementos como o hélio, o néon, a prata ou a platina existem como unidades de átomos individuais independentes. Outros elementos como o hidrogênio, o oxigênio ou o enxofre existem como unidades de dois ou mais átomos idênticos. Estes átomos múltiplos são mantidos juntos por fortes forças eletrostáticas identificadas como ligações químicas, que formam unidades estáveis denominadas de moléculas.Para além disso, dois ou mais elementos diferentes também podem combinar-se para formarem moléculas como a água ou a frutose. Tais moléculas que são formadas pela combinação de átomos de dois ou mais elementos, unidos quimicamente numa proporção fixa, são também denominados de compostos. Assim, as moléculas da água e da frutose também são compostas.A água é a molécula formada por dois átomos de hidrogênio e um átomo de oxigênio. Em contrapartida, a frutose é uma molécula que contém seis átomos de carbono, doze átomos de hidrogênio e seis átomos de oxigénio. Os átomos individuais num composto são mantidos juntos através de ligações químicas, ditando o tipo de composto formado tal como um composto molecular iônico.Compostos moleculares covalentes, como a água, formam-se quando os átomos não metálicos se juntam e partilham os seus elétrons de valência através de uma ligação covalente. Os elétrons partilhados entre dois átomos diminuem a energia potencial e criam mais moléculas estáveis em comparação com os átomos individuais. Os compostos iônicos, como o cloreto de sódio, formam-se quando os átomos metálicos e não metálicos se juntam.Os metais perdem facilmente os elétrons, tornando-se cátions, enquanto que os não metais ganham rapidamente elétrons, tornando-se aníons. Assim, os átomos metálicos transferem elétrons para os átomos não metálicos e as interações eletrostáticas entre os íons carregados de forma oposta formam ligações iónicas. A capacidade dos elementos para formarem compostos contribui para a grande diversidade da matéria que existe na natureza.

moléculas e compostos

<h4>Átomos e Moléculas </h4>

Tudo no universo é composto por matéria, e a matéria é composta por uma combinação de elementos. Um átomo é a menor unidade de um elemento que retém todas as propriedades do elemento. Por exemplo, uma moeda de prata é composta por átomos de prata, e cada átomo de prata mantém as propriedades únicas do elemento — prata. 

Os elementos são substâncias puras constituídas por átomos idênticos que não podem ser divididas em substâncias mais simples por alterações químicas. Elementos atómicos contêm átomos únicos como a sua unidade básica. O carbono é composto por átomos de carbono, e o sódio é composto por átomos de sódio. A maioria dos elementos são elementos atómicos. Há, no entanto, alguns elementos que existem como uma combinação de átomos, e nunca são encontrados na natureza como átomos únicos. Estes são chamados elementos moleculares. Os elementos moleculares existem como moléculas com dois ou mais átomos unidos. Podem ser diatómicos, como hidrogénio (H2), oxigénio (O2), ou cloro (Cl2), ou poliatómicos, como enxofre (S8) e fósforo (P4). 

Uma molécula consiste em dois ou mais átomos unidos por forças fortes chamadas ligações químicas. Uma molécula pode consistir em dois ou mais átomos idênticos , ou pode consistir em dois ou mais átomos diferentes.  Quando a molécula consiste em átomos de dois ou mais elementos diferentes que são combinados em proporções fixas de número inteiro, a molécula também é um composto. Por exemplo, a água é um composto, e cada molécula de água (H2O) é uma unidade que contém dois átomos de hidrogénio e um átomo de oxigénio. A glicose molecular (C6H12O6) é também um composto que contém seis átomos de carbono, doze átomos de hidrogénio, e seis átomos de oxigénio. 

Compostos são  substâncias puras compostas por dois ou mais elementos em proporções fixas e definidas. Os compostos são classificados como moleculares ou iónicos com base nas ligações presentes. 

<h4>Compostos</h4>

A natureza das forças atrativas que mantêm átomos juntos dentro de um composto decide o tipo de ligação química formada. A transferência completa de eletrões entre um átomo de metal e um átomo não metálico resulta na formação de iões de carga oposta. A atração eletrostática entre os iões é chamada de ligação iónica, e os compostos formados por ligações iónicas são compostos iónicos. Por exemplo, o cloreto de sódio NaCl é um composto iónico.

A partilha de eletrões entre dois ou mais átomos não metálicos resulta em ligações covalentes e os compostos formados através de ligações covalentes são denominados compostos covalentes ou moleculares. As ligações covalentes são as forças atrativas entre os núcleos positivamente carregados dos átomos ligados e os eletrões negativamente carregados, partilhados entre os átomos.

Este texto é adaptado de <a href="https://openstax.org/books/chemistry-2e/pages/2-6-molecular-and-ionic-compounds">OpenStax Chemistry 2e, Section 2.6: Molecular and Ionic Compounds.</a>

Moléculas e Compostos

Átomos e Moléculas

Tudo no universo é feito de matéria, e a matéria é composta de uma combinação de elementos. Um átomo é a menor unidade de ...

Education

JoVE Core

Química

Molecules, Compounds, and Chemical Equations

Moléculas, Compostos e Equações Químicas

molecules-compounds-and-chemical-equations

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

atomic elements, molecules, and bonds

Matter is made of elements, and elements are built from atoms. An atom is the smallest unit of an element that still keeps that element’s properties. A silver coin, for example, is made of silver atoms. Each atom keeps the unique properties of silver.

Elements are pure substances made of identical atoms. They cannot be broken down into simpler substances by chemical changes. Most elements are atomic elements, which use single atoms as their basic unit. Carbon and sodium are examples of atomic elements.

Some elements do not occur as single atoms in nature. These are called molecular elements. They exist as molecules made of two or more bonded atoms. Some are diatomic, such as hydrogen (H2), oxygen (O2), and chlorine (Cl2). Others are polyatomic, such as sulfur (S8) and phosphorous (P4).

A molecule is a group of two or more atoms joined by strong chemical bonds. The atoms in a molecule may be the same, or they may be different. When a molecule contains atoms from two or more different elements in fixed whole number ratios, it is also a compound. Water is a compound, and each H2O molecule has two hydrogen atoms and one oxygen atom. Glucose (C6H12O6) is another compound, with six carbon atoms, twelve hydrogen atoms, and six oxygen atoms.

Compounds are pure substances made of two or more elements in fixed, definite proportions. They are classified as molecular or ionic based on the bonds they contain. The kind of attraction between atoms determines the bond type. When electrons transfer completely from a metal atom to a nonmetal atom, oppositely charged ions form. The electrostatic attraction between those ions is an ionic bond, and the result is an ionic compound such as sodium chloride (NaCl). When two or more nonmetal atoms share electrons, they form covalent bonds. Compounds formed this way are covalent, or molecular, compounds.

Atomic Elements, Molecules, and Bonds

molecules and compounds

Matter is made of elements, and elements are built from atoms. An atom is the smallest unit of an element that still keeps that element’s properties. A silver coin, for example, is made of silver atoms. Each atom keeps the unique properties of silver. Elements are pure substances made of identical atoms. They cannot be broken down into simpler substances by chemical changes. Most elements are atomic elements, which use single atoms as their basic unit. Carbon and sodium are examples of atomic...

molecular models

Molecular Model Types in Chemistry

Molecular models help chemists and students visualize the structures and shapes of atoms and molecules. They represent the molecular architecture of chemical compounds in a way that is easier to study than formulas alone. Skeletal models are simple two-dimensional drawings of compounds. They show the molecular framework, or the bonds, without drawing every atom. In this model, many carbon and hydrogen atoms are not shown directly. Their positions are implied by the ends and junctions of the...

organic compounds

Organic Molecules in Everyday Chemistry

Organic molecules are carbon-based compounds found in living things and in many everyday products. Most organic compounds have carbon as the main element, bonded to hydrogen and other carbon atoms. Some carbon-containing substances, such as carbonates, cyanides, and simple oxides like CO and CO2, are not classified as organic. Carbon can form up to four strong bonds, which helps explain why organic compounds can make chains and rings of many sizes and shapes. These molecules appear in...

formula mass and mole concepts of compounds

formula-mass-and-mole-concepts-of-compounds

Chemical Formula Mass and Percent Composition

Chemical formula mass and percent composition help describe the makeup of compounds. A chemical formula shows which atoms are present and how many of each atom appear in a substance. For covalent compounds, the formula shows the atoms in one molecule. That is why formula mass can also be called molecular mass. Chloroform, CHCl3, is one example. Its formula shows one carbon atom, one hydrogen atom, and three chlorine atoms. The molecular mass is the sum of their average atomic masses. Ionic...

experimental determination of chemical formula

experimental-determination-of-chemical-formula

Finding Empirical and Molecular Formulas

Chemical formulas show the elemental makeup of a compound. When a formula is unknown, scientists often start by measuring the masses of the elements in the sample. Those mass data are then used to find the simplest whole-number ratio of atoms, which gives the empirical formula. To get from mass to atom ratio, the masses of the elements are first converted to moles using molar masses. Chemical formulas describe numbers of atoms, not masses, so this step is necessary. In one example, 1.71 grams...

chemical equations

Reading Chemical Equations and Balancing Them

Chemical equations show the identities and relative amounts of substances in a chemical reaction. The substances that react are called reactants, and their formulas are written on the left side of the equation. The substances formed are called products, and their formulas are written on the right side. A plus sign (+) separates formulas on the same side, and an arrow (→) shows the change from reactants to products. The numbers in a chemical equation are shown with coefficients. A coefficient...

key terms and concepts

Learn how atoms form elements, molecules, and compounds, and compare ionic and covalent bonds using examples like water, glucose, and sodium chloride.

Atomic Elements, Molecules, and Bonds | 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.

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Physical Science

PS.PSc.1.1

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Ohio’s Learning Standards and Model Curriculum

Study Of Matter

Classification of matter

Virginia  Standards of Learning

HIgh School

CH.3

CH.3.a

Alabama Course of Study Science

Matter and Its Interactions

9-12.PS.3.4.c

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South Carolina College and Career Ready Science Standards

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The Scientific Method

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The Atomic Theory of Matter

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Subatomic Particles

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Elements: Chemical Symbols and Isotopes

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Radioactivity and Nuclear Equations

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Nuclear Binding Energy

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Radioactive Decay and Radiometric Dating

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Nuclear Fission

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Nuclear Power

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The Pauli Exclusion Principle

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Intermolecular vs Intramolecular Forces

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Surface Tension
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Hydrogen Bonds

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Van der Waals Interactions

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Construct an explanation to summarize the influences intermolecular forces have on the properties of chemical compounds.

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Molecular Models

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Classification of Elements and Compounds

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Ionic Compounds: Formulas and Nomenclature

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Molecular Compounds: Formulas and Nomenclature

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Use models to predict chemical names and formulas including ionic (binary & ternary), acidic, and binary covalent compounds.

Analyze the structure of atoms and isotopes.

Atomic Elements, Molecules, and Bonds

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