Name: reading molecular, empirical, and structural formulas
Uploaded: 2020-09-03T13:38:26.000Z
Duration: 2 min 52 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

Chemistry

Matter and its Interactions

PS.Chm.3.3

Chemical Formulas

화합물은 둘 이상의 원소가 특정 비율로 구성된 물질입니다. 이러한 화합물을 정확하게 설명하기 위해 화학식이 생겨나게 되었습니다. 화학식은 원소와 그와 관련된 이온 또는 원자의 수에 대한 정보를 제공합니다.

원소는 화학 기호로 표시되며 이온 또는 원자의 상대적인 수는 아래 첨자의 수로 표시됩니다. 예를 들어, 설탕이나 자당류는 탄소와 수소, 그리고 산소를 포함하는 화합물이며 각각의 기호 C, H, O를 사용하여 표현됩니다. 숫자 12, 22, 11은 화합물 내에 존재하는 탄소, 수소, 산소 원자의 총 수를 나타냅니다.

일반적으로 원소는 알파벳 순서로 나열되는 것이 아니라 양전하 또는 금속 원소로 시작하여 음전하 또는 덜 금속적인 원소로 배열합니다. 수산화칼륨과 같이 말이죠. 화학식은 분자식, 실험식, 구조식으로 분류됩니다.

분자식은 각 원소와 존재하는 원자의 정확한 수를 나열하는 것으로 화합물을 나타냅니다. 포도당의 분자식은 C six H twelve O six 인데 이는 포도당이 탄소 여섯 개, 수소 열 두 개, 산소 여섯 개로 구성되어 있다는 뜻입니다. 실험식은 존재하는 원소의 원자들에 대한 가장 간단한 정수 비율을 표시합니다.

포도당에서 탄소, 수소, 산소 원자의 가장 단순한 비율은 1대 2대 1이므로 실험식은 C H two O로 됩니다. 화합물의 분자식은 실험식의 정수배수입니다. 포도당에서는 실험식에 정수 6을 곱하면 분자식이 됩니다.

이와는 대조적으로 구조식은 개별 원자들 사이의 관계를 그래픽으로 나타냅니다. 화학 기호는 원자를 나타내고 짧은 선들은 화학적 결합을 나타냅니다. 단일 라인은 단일 결합을 나타내며 이중 라인과 삼중 라인은 각각 이중 결합 및 삼중 결합을 나타냅니다.

투시도, 공-막대모형 또는 공간 충전 모형과 같은 구조식의 확장된 모형에서는 분자 모양에 대한 다양한 3차원적 표현을 제공합니다. 세 가지 화학식 중에서, 구조식이 화학 물질에 대한 가장 많은 정보를 제공하며 그 다음은 분자식입니다. 실험식이 전달하는 정보량이 제일 적습니다.

화학 공식

화학식은 주로 원소 기호와 숫자를 사용하여 특정 화합물이나 분자를 구성하는 원자의 비율에 대한 정보를 나타냅니다. 때로는 대시, 괄호, 대괄호, 쉼표, 더하기 및 빼기 기호와 같은 다른 기호도 사용됩니다. 화학식은 분자식, 실험식, 구조식의 세 가지 유형 중 하나일 수 있습니다.

분자식

분자식은 화학 기호(원자의 유형을 나타냄)와 아래 첨자 숫자(분자 내 각 유형의 원자 수를 나타냄)를 사용하여 분자 또는 화합물을 나타냅니다. 분자식은 화합물 이름의 약어로도 사용됩니다.

일부 원소는 비활성 기체인 헬륨, 네온, 아르곤과 같은 별개의 개별 원자로 구성됩니다. 이러한 원소를 단원자 기체라고 하며 각각 He, Ne 및 Ar의 분자식을 갖습니다. 동일한 원소의 두 개 이상의 화학적 결합 원자로 구성된 분자로 존재하는 원소는 거의 없습니다. 예를 들어, 수소, 산소, 질소와 같은 원소는 각각 두 개의 원자를 포함하는 이원자 분자로 존재하므로 각각 분자식 H_2, O_2, N_2를 갖습니다. 마찬가지로, 인과 황과 같은 원소는 각각 분자식 P_4와 S_8을 갖는 다원자 분자로 존재합니다.

기호 뒤의 아래 첨자와 기호 앞의 숫자는 동일한 것을 나타내지 않는다는 점에 유의하는 것이 중요합니다. 예를 들어, H_2와 2H는 뚜렷이 다른 종을 나타냅니다. H_2는 분자식이다. 그것은 화학적으로 결합된 두 개의 원소 원자로 구성된 수소의 이원자 분자를 나타냅니다. 반면에 2H라는 표현은 하나의 단위로 결합되지 않은 두 개의 분리된 수소 원자를 나타냅니다. 2H_2라는 표현은 이원자 수소 두 분자를 나타냅니다.

실험식

화합물은 두 개 이상의 원소가 화학적으로 결합하여 결합을 형성할 때 형성됩니다. 예를 들어, 수소와 산소는 반응하여 물을 형성할 수 있고, 나트륨과 염소는 반응하여 염화나트륨이나 식염을 형성할 수 있습니다. 우리는 때때로 존재하는 원자의 유형과 화합물에 포함된 원자(또는 이온) 수의 가장 간단한 정수 비율을 나타내는 실험식을 사용하여 이러한 화합물의 구성을 설명합니다. 예를 들어, 이산화티타늄(흰색 페인트와 두껍고 흰색의 차단형 자외선 차단제에 안료로 사용됨)의 실험식은 TiO_2입니다. 이는 티타늄(Ti)과 산소(O) 원소가 이산화티타늄의 구성 성분임을 확인하고, 티타늄 원소 원자보다 산소 원소 원자가 두 배 더 많이 존재함을 나타냅니다.

많은 경우 물질의 분자식은 실험식과 분자 질량(분자를 구성하는 모든 원자의 원자 질량의 합)의 실험적 결정에서 파생됩니다. 예를 들어, 벤젠에는 탄소(C)와 수소(H)라는 두 가지 원소가 포함되어 있으며 벤젠의 모든 탄소 원자에는 수소 원자가 1개 있다는 것을 실험적으로 확인할 수 있습니다. 따라서 실험식은 CH입니다. 분자 질량을 실험적으로 측정한 결과 벤젠 분자에는 6개의 탄소 원자와 6개의 수소 원자가 포함되어 있으므로 벤젠의 분자식은 C_6H_6입니다.

구조식

화합물의 구조식은 분자식과 동일한 정보(분자 내 원자의 유형 및 수)를 제공하지만 원자가 분자 내에서 어떻게 연결되어 있는지도 보여줍니다. 즉, 구조식은 화합물의 분자 구조를 그래픽으로 나타냅니다. 이는 원자의 예상되는 배열과 원자가 실제 3차원 공간에서 어떻게 연결되어 있는지 보여줌으로써 분자 기하학에 대한 더 많은 정보를 제공합니다. 선은 원자 사이에 존재하는 결합을 나타내는 데 사용됩니다. 공식은 대략적인 결합각을 묘사하여 분자의 모양을 알려줄 수도 있습니다.

이 문서는 에서 발췌되었습니다  <a href="https://openstax.org/books/chemistry-2e/pages/2-4-chemical-formulas">Openstax Chemistry 2e, Section 2.4: Chemical Formulas.</a>

화학식은 특정 화합물 또는 분자를 구성하는 원자의 비율에 대한 정보를 제공하며, 주로 ...

Education

교육

Book

화학

Molecules, Compounds, and Chemical Equations

분자, 화합물 및 화학 방정식

molecules-compounds-and-chemical-equations

reading molecular, empirical, and structural formulas

Chemical formulas show the types and proportions of atoms in a compound or molecule. They use element symbols and numbers. Some formulas also use dashes, parentheses, brackets, commas, plus signs, and minus signs.

A molecular formula shows a molecule or compound with chemical symbols and subscript numbers. The symbols tell which atoms are present, and the subscripts show how many of each atom are in the molecule. Molecular formulas can also serve as short names for compounds.

Some elements exist as separate atoms. The noble gases helium, neon, and argon are monatomic gases, so their molecular formulas are He, Ne, and Ar. Other elements form molecules with two or more bonded atoms of the same element. Hydrogen, oxygen, and nitrogen are diatomic and have the formulas H2, O2, and N2. Phosphorus and sulfur are polyatomic and have the formulas P4 and S8.

It is important to tell the difference between a subscript and a number in front of a symbol. H2 means one diatomic hydrogen molecule. The expression 2H means two separate hydrogen atoms. The expression 2H2 means two hydrogen molecules.

An empirical formula shows the types of atoms present and the simplest whole-number ratio of those atoms or ions in a compound. Compounds form when two or more elements chemically combine and make bonds. Water and sodium chloride are common examples of compounds. Titanium dioxide has the empirical formula TiO2, which shows titanium and oxygen and means there are twice as many oxygen atoms as titanium atoms.

In many cases, a molecular formula is found from the empirical formula and the molecular mass. Molecular mass is the sum of the atomic masses of all atoms in a molecule. Benzene is one example. Experiments show that benzene contains carbon and hydrogen in a 1:1 ratio, so its empirical formula is CH. Its molecular mass shows that one molecule contains six carbon atoms and six hydrogen atoms, so its molecular formula is C6H6.

A structural formula gives the same atom count information as a molecular formula, but it also shows how the atoms are connected. It draws the molecular structure in a way that helps show the probable arrangement of atoms in three-dimensional space. Lines represent bonds between atoms. Structural formulas may also show approximate bond angles, which gives a sense of molecular shape.

Reading Molecular, Empirical, and Structural Formulas

reading-molecular-empirical-and-structural-formulas

chemical formulas

Chemical formulas show the types and proportions of atoms in a compound or molecule. They use element symbols and numbers. Some formulas also use dashes, parentheses, brackets, commas, plus signs, and minus signs. A molecular formula shows a molecule or compound with chemical symbols and subscript numbers. The symbols tell which atoms are present, and the subscripts show how many of each atom are in the molecule. Molecular formulas can also serve as short names for compounds. Some elements...

molecules and compounds

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...

classification of elements and compounds

Atomic vs Molecular Substances and Bonding

Pure substances are made of only one kind of matter. A pure substance can be an element or a compound. An element contains only one type of atom. A compound contains two or more types of atoms joined by a chemical bond. Elements are classified as atomic or molecular based on their basic units. Compounds are classified as ionic or molecular, also called covalent, based on the bonds they contain. Molecular compounds form when two or more different nonmetal atoms share electrons. Their basic...

ionic compounds: formulas and nomenclature

ionic-compounds-formulas-and-nomenclature

Ionic Charges, Formulas, and Naming Rules

Ionic compounds form when metals transfer electrons to nonmetals and create oppositely charged ions. The electrostatic attraction between the ions, called an ionic bond, holds the compound together. Many nonmetals gain electrons by moving toward the electron count of the next noble gas. Group 17 atoms usually gain one electron and form 1− ions, while group 16 atoms usually gain two electrons and form 2− ions. Oxygen is a clear example. A neutral oxygen atom has 8 protons and 8 electrons. When...

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...

molecular compounds: formulas and nomenclature

molecular-compounds-formulas-and-nomenclature

Naming Covalent Compounds and Acids

Molecular compounds are covalent compounds made when atoms share electrons. Because there is no electron transfer, they do not contain ions. They are made of separate, neutral molecules. Since covalent compounds usually form from nonmetals, the periodic table can help students recognize many of them. In many cases, the positions of the elements can also help predict whether a compound is ionic or covalent, although there are exceptions. Molecular compounds are named differently from ionic...

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...

scientists in action

활동 중인 과학자들

key terms

주요 용어

key relationships & equations

주요 관계 및 방정식

chapter exercises

장별 연습 문제

appendices

부록

molecules, compounds, and chemical equations

Learn how molecular, empirical, and structural formulas show atom counts, ratios, and bonds. See examples like H2, TiO2, and C6H6.

Reading Molecular, Empirical, and Structural Formulas | JoVE K12

chemistry

PS.Chm.4.3

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Structure And Properties Of Matter

Representing compounds

Virginia  Standards of Learning

HIgh School

CH.3

CH.3.a

Texas Essential Knowledge and Skills

High School

CHEM.8

CHEM.8.D

Florida Department of Education

Physical Science

SC.912.P.8

SC.912.P.8.7

Georgia Standards of Excellence

SPS2.

Chemical Names and Chemical Formulas

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

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

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

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

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

Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

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

Lewis Structures of Molecular Compounds and Polyatomic Ions

To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:


	Determine the ...

Resonance

The Lewis structure of a nitrite anion (NO2&minus;) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...

Formal Charges

In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...

Exceptions to the Octet Rule

Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:


	...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Analyze and interpret data to explain the mechanisms and properties of the two main types of intramolecular (ionic and covalent) bonds.

PS.Chm.3.1

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, ...

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

PS.Chm.3.2

Analyze the structure of atoms and isotopes.

Reading Molecular, Empirical, and Structural Formulas

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