Name: atomic orbitals and quantum numbers
Uploaded: 2023-04-30T18:28:31.000Z
Duration: 2 min 28 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-1

Electronic Structure of Atoms

Atom składa się z trzech cząstek subatomowych – elektronów, protonów i neutronów. Dodatnio naładowane protony i elektrycznie obojętne neutrony tworzą jądro atomowe, w którym znajduje się cały ładunek dodatni i większość masy atomu.
Elektrony to ujemnie naładowane, małomasywne składniki znajdujące się w pustej przestrzeni wokół jądra. Atom jest elektrycznie obojętny, gdy ma tyle samo elektronów, co protonów.
Elektrony mają dwoistą naturę – cząstkę i falę. Ich usytuowanie w przestrzeni i energia są właściwościami uzupełniającymi. Dlatego dla elektronu o dobrze zdefiniowanej energii jego położenie jest niepewne.
Model kwantowo-mechaniczny atomu przewiduje, że prawdopodobieństwo znalezienia elektronu o danej energii w trójwymiarowym obszarze przestrzeni można wyznaczyć na podstawie kwadratu funkcji falowej wyrażającej falową naturę elektronu, zwaną również gęstością prawdopodobieństwa elektronu.
Funkcja opisująca prawdopodobne położenie przestrzenne elektronu o określonej energii w atomie nazywana jest orbitalem atomowym.
Każdy orbital odpowiada unikalnej kombinacji trzech liczb kwantowych. Główna liczba kwantowa, n, grupuje orbitale w poziomy energetyczne lub powłoki.
Moment pędu lub azymutalna liczba kwantowa, l, grupuje orbitale w powłokach w podpowłoki. Każda wartość l odpowiada orbitalowi s, p, d lub f o różnym kształcie.
Niektóre kształty orbit mogą mieć wiele możliwych orientacji, z których każda jest związana z magnetyczną liczbą kwantową, ml. Liczba orientacji dla danej podpowłoki jest równa dwa-l plus jeden.
Czwarta liczba kwantowa – spinowa liczba kwantowa, m s – jest związana z elektronami zajmującymi orbital i ma tylko dwie możliwe wartości: "plus połowę" i "minus połowę". Gwarantuje to, że żadne dwa elektrony w atomie nie mają takich samych wartości dla wszystkich czterech liczb kwantowych.
Nakładanie orbitali jeden na drugi tworzy mniej więcej kulisty kształt, podobny do "chmury" elektronów otaczających jądro. Dlatego atomy są zwykle przedstawiane jako kule.

elektroniczna struktura atomów

Atom składa się z protonów i neutronów, które znajdują się w gęstym, centralnym rdzeniu zwanym jądrem, a elektrony są obecne wokół jądra. Biorąc pod uwagę dualizm falowo-cząsteczkowy elektronów i niepewność położenia wokół jądra, mechanika kwantowa dostarcza dokładniejszego modelu struktury atomu. Opisuje orbitale atomowe jako obszary wokół jądra, w których istnieją elektrony o energii dyskretnej, charakteryzujące się czterema liczbami kwantowymi: n, l, m_l i m_s.

Model mechaniki kwantowej

Atom składa się z małego, dodatnio naładowanego jądra otoczonego elektronami. Jądro zawiera protony i neutrony. Protony mają ładunek +1 i masę 1,0073 amu. Neutrony mają ładunek zerowy i masę 1,0087 amu. Elektrony mają ładunek -1 i masę 0,00055 amu. Liczba protonów w jądrze nazywana jest liczbą atomową (Z) i określa tożsamość pierwiastkową atomu. Suma liczby protonów i neutronów w jądrze nazywana jest liczbą masową i wyrażana w amu jest w przybliżeniu równa masie atomu. Atom jest obojętny, gdy zawiera równą liczbę elektronów i protonów.

Zaproponowano różne modele opisujące strukturę atomową wyjaśniające rozkład elektronów wokół jądra. Relacja de Broglie'a określiła ilościowo, że elektrony mają właściwości zarówno cząstki, jak i fali. Dalej kwantyfikując tę dualność falowo-cząsteczkową, Heisenberg podał zasadę nieoznaczoności: położenia (związanego z naturą cząstki) i prędkości lub energii (związanej z naturą falową) elektronu nie można określić jednocześnie z pełną precyzją. Model mechaniki kwantowej daje dokładniejszy obraz struktury atomu. Opisuje trójwymiarowe położenie elektronu o określonej energii, zawartego w atomie, w sposób probabilistyczny pod względem kwadratu funkcji falowej ψ^2. Funkcja falowa opisuje stan elektronu w atomie, a jej kwadrat określa rozkład prawdopodobieństwa znalezienia elektronu w danym obszarze – zwanym orbitalem atomowym

Orbital atomowy charakteryzuje się trzema liczbami kwantowymi. Główna liczba kwantowa n grupuje orbitale pod względem lokalizacji poziomu energii, czyli „powłoki”. Moment pędu lub azymutalna liczba kwantowa l grupuje orbitale na podstawie ich kształtów w „podpowłoki”. Ma wartości całkowite od 0 do n – 1 i jest reprezentowany przez litery: s (l = 0), p (l = 1), d (l = 2), f (l = 3), g (l = 4) i h (l = 5). Magnetyczna liczba kwantowa, m_l, o wartościach 2l + 1 w zakresie od –l do +l, opisuje orientację orbitalu w przestrzeni. Ponadto każdy elektron ma spinową liczbę kwantową, m_s, która może wynosić ±1/2. Żadne dwa elektrony w tym samym atomie nie mogą mieć tego samego zestawu wartości dla wszystkich czterech liczb kwantowych.

Ten tekst jest adaptacją<a href="https://openstax.org/books/chemistry-2e/pages/6-3-development-of-quantum-theory#0"> Openstax, ********* 2e, Section 6</a>.

Elektroniczna struktura atomów


Atom składa się z protonów i neutronów, które są zawarte w gęstym, centralnym jądrze zwanym jądrem, z elektronami obecnymi wokół ...

Education

JoVE Core

Organic Chemistry

Chemia organiczna

Unit 1

Jednostka 1

Covalent Bonding and Structure

Wiązania kowalencyjne i struktura

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

atomic orbitals and quantum numbers

Atomic orbitals and quantum numbers describe how electrons are arranged around the nucleus. An atom has a small, positively charged nucleus with electrons surrounding it. The nucleus contains protons and neutrons, and the quantum mechanical model gives a better picture of this structure than older models.

Protons carry a +1 charge and have a mass of 1.0073 amu. Neutrons have no charge and have a mass of 1.0087 amu. Electrons carry a −1 charge and have a mass of 0.00055 amu. The number of protons is the atomic number, Z, and it defines the element. The total number of protons and neutrons is the mass number, and it is approximately equal to the atom’s mass in amu. An atom is neutral when it has equal numbers of protons and electrons.

The quantum model grew from ideas about electron behavior. The de Broglie relation showed that electrons act like both particles and waves. Heisenberg’s uncertainty principle added that an electron’s position and its velocity or energy cannot both be known with full precision at the same time. Because of this, electron location is described in a probabilistic way using the square of the wavefunction, ψ².

Atomic wavefunctions, or atomic orbitals, show the regions where electrons are most likely to be found. Orbitals are described by four quantum numbers. The principal quantum number, n, gives the energy level or shell. The angular momentum, or azimuthal, quantum number, l, describes orbital shape and forms subshells. Its values run from 0 to n − 1, and the labels are s, p, d, f, g, and h for l = 0 through 5.

The magnetic quantum number, ml, describes how an orbital is oriented in space. It has 2l + 1 possible values, ranging from −l to +l. The spin quantum number, ms, can be +1/2 or −1/2. No two electrons in the same atom can have the same set of values for all four quantum numbers.

Atomic Orbitals and Quantum Numbers

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Carbon Compounds in Everyday Life

Organic chemistry focuses on carbon compounds called organic compounds. These compounds may come from living things or be made by chemists. Carbon is the main element in them, and it bonds with other carbon atoms as well as hydrogen, oxygen, nitrogen, and sulfur. Carbon can form up to four strong bonds. That ability lets carbon atoms build chains and rings of many sizes, shapes, and levels of complexity. Not every carbon-containing substance is classified as organic. Carbonates, cyanides, and...

electronic structure of atoms

Atomic orbitals and quantum numbers describe how electrons are arranged around the nucleus. An atom has a small, positively charged nucleus with electrons surrounding it. The nucleus contains protons and neutrons, and the quantum mechanical model gives a better picture of this structure than older models. Protons carry a +1 charge and have a mass of 1.0073 amu. Neutrons have no charge and have a mass of 1.0087 amu. Electrons carry a −1 charge and have a mass of 0.00055 amu. The number of...

electron configurations

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chemical bonds

Chemical Bonds: Types and Strength

Chemical bonds help atoms reach a full valence shell like the nearest noble gas. The main bond types are ionic, covalent, and metallic. Bond energy and bond length also help explain how strong a bond is. An ionic bond forms from electrostatic attraction between cations and anions. In many cases, one atom transfers electrons to another atom, and the ions form from that transfer. Ionic bonds have no defined direction because the attraction spreads evenly through three-dimensional space. A...

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Covalent Bond Overlap and Orbital Hybridization

Covalent bonds form when orbitals on two atoms overlap and their single electrons pair up. The bond is stronger when the overlap is greater. Maximum overlap happens when the orbitals meet along a direct line between the two nuclei. A sigma bond, or σ bond, is the kind of covalent bond found in a single bond in a Lewis structure. In a σ bond, electron density is concentrated along the internuclear axis. A pi bond, or π bond, forms when two p orbitals overlap side by side. In a π bond, the...

mo theory and covalent bonding

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intermolecular forces and physical properties

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solubility

Why Some Substances Dissolve in Water

Solution formation depends on how solutes and solvents interact. A solution is a homogeneous mixture made of a solvent, which is the larger part, and a solute, which is the smaller part. The physical state of a solution is usually the same as the solvent. Concentration is often described as dilute for a low amount of solute or concentrated for a high amount of solute. When a solute dissolves, its particles are surrounded by solvent species. This process is called solvation. If water is the...

introduction to functional groups

Functional Groups and Organic Molecules

Functional groups are groups of atoms with specific chemical properties that appear within organic molecules. They are sometimes shown as "R." These groups sit along the carbon backbone of macromolecules, which can form chains or rings of carbon atoms. Functional groups help functionalize a compound. That means they can give the molecule different physical and chemical properties. In organic chemistry, this change in group structure can strongly affect how a compound behaves. Common...

overview of advanced functional groups

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Advanced functional groups are atom clusters in organic molecules that give those molecules specific chemical properties. They are sometimes shown as "R" in formulas. By changing the atoms attached to a carbon skeleton, a functional group can make a compound behave differently in physical and chemical reactions. This topic covers several major classes of organic compounds with advanced functional groups. Aromatic hydrocarbons include benzene. Phenol is another example and is also called...

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Atomic Orbitals and Quantum Numbers | JoVE K12

organic chemistry

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Atomic Orbitals and Quantum Numbers

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