Name: electron spin and orbital pairing
Uploaded: 2020-09-03T13:38:27.000Z
Duration: 3 min 6 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry and Physics

IPC.7

IPC.7.E

The Pauli Exclusion Principle

المدارات الذرية هي المناطق حيث إلكترونات الذرة أكثر احتمالاًللتواجد. لكن كم عدد الإلكترونات التي يمكن لكل مدار أن يحملها؟يجيب مبدأ باولي الاستبعادي على هذا السؤال،لأنه يعني انه لا يوجد إلكترونين في الذرة يمكن أن يكون لهما نفس المجموعة المكونة من أربعة أرقام كميه. كل مدار يتوافق مع أصل ثابت الزخم الزاوي،أو السمتي وقيم الرقم الكم المغناطيسي.على سبيل المثال،إلكترون في المدار 1s دائما لديه رقم كمي رئيسي،هو واحد وأعداد الكم السمتي والمغناطيسية،هو صفر. وفقًا لذلك،يجب أن يكون للإلكترونات عدد كمي مغزلي مختلف القيم،أو يدور،للاقامة في نفس المدار الذري. لنتذكر أن أعدد كم الدوران لها قيمتان محتملتان فقط:1/2 و 1/2.لذلك،يمكن لإلكترونين فقط شغل نفس المدار. ومن ثم،كل قشرة s فرعية لها مدار واحد،يمكن أن تستوعب إلكترونين فقط،وكل قشرة p فرعية لها ثلاثة مدارات،يمكنه حمل ستة إلكترونات. كل من القشور الفرعية d و f لها سعة قصوى تبلغ عشرة وأربعة عشر إلكترونًا على التوالي.توزيع الإلكترونات بين المدارات الذرية للذرة يتم تمثيله من خلال تكوينه الإلكتروني في شكل نص أو رسم تخطيطي. لننظر في حالة ذرة الهيدروجين على الأرض،حيث يشغل إلكترون واحد المدار الأقل طاقة:1s. تكوين الإلكترون المكتوب يشير إلى كل طبقة فرعية مشغولة رقم الغلاف المقابل،والحرف الممثل للطبقة الفرعية،ورقم علوي يحدد رقم الإلكترونات في الغلاف الفرعي.نمط الرسم البياني المداري لتكوين الإلكترون يشير إلى كل مدار داخل قشرة فرعية مشغولة كمربع أو خط،وكل إلكترون كسهم. يشير السهم المتجه لأعلى إلى دوران 1/2 أو دوران لاعلي،والسهم المتجه لأسفل يشير إلى 1/2 دوران أو دوران لأسفل. وبالتالي،فإن المخطط المداري للهيدروجين سهم واحد متجه لأعلى.التكوين الإلكتروني للهيليوم هو 1s 2. للإلكترونين ثلاثة أرقام كمية متطابقة،لأنهم ينتمون إلى نفس الغلاف والقشرة الفرعية. بينما أعدادهم الكمية المغزلية مختلفة،وفقًا لمبدأ استبعاد باولي.تسمى الإلكترونات ذات الدورانات المعاكسة المتزاوج"إذا كانت تشغل نفس المدار. بالنسبة لليثيوم،الذي يحتوي على العدد الذري ثلاثة،يكون الإلكترونين في المدار 1s متزاوج بينما الإلكترون الموجود في مدار 2s غير متزاوج. تقليديا،الإلكترونات غير المتزاوجة يتم تمثيلها على أنها دورانية.

مبدأ استبعاد باولي

يُطلق على ترتيب الإلكترونات في المدارات الخاصة بالذرة اسم تكوين الإلكترونات الخاص بها. نحن نصف التكوين الإلكتروني برمز يحتوي على ثلاثة أجزاء من المعلومات: <ol><li>عدد القشرة الكمية الرئيسية،n، </li><li>الحرف الذي يعيّن نوع المداري (الهيكل السفلي،l)، و </li><li>رقم علوي يعيّن عدد الإلكترونات في ذلك الغلاف الفرعي المحدد. </li></ol>على سبيل المثال، يشير الرمز 2p4 إلى أربعة إلكترونات في p الغلاف الفرعي (l = 1) بعدد الكم الأساسي (n) من 2. يشير الرمز 3d 8 إلى ثمانية إلكترونات في d الغلاف الفرعي ( l = 2) من الغلاف الرئيسي الذي له n = 3.بينما تعمل الأعداد الكمومية الثلاثة بشكل جيد لوصف المدارات الإلكترونية، أظهرت بعض التجارب أنها غير كافية لشرح كل النتائج التي تمت ملاحظتها. وقد ثبت في العشرينات أنه عندما يتم فحص أطياف خط الهيدروجين بدقة عالية للغاية، فإن بعض الخطوط ليست في الواقع ذروات مفردة، بل هي في الواقع أزواج من الخطوط المتباعدة بشكل وثيق. وهذا ما يسمى بالبنية الدقيقة للطيف، ويعني ضمناً وجود اختلافات صغيرة إضافية في طاقات الإلكترونات حتى عندما تكون موجودة في نفس المستوى. وقد دفعت هذه الملاحظات صموئيل جودسما وجورج أوهلينبيك إلى اقتراح أن الإلكترونات لها رقم كمومي رابع. هم سمّوا هذا بالرقم الكمومي الدوراني ms.في مجال مغناطيسي مطبّق، يكون للإلكترونات اتجاهين محتملين مع طاقات مختلفة، واحد مع الدوران لأعلى، ومحاذاة مع المجال المغناطيسي، وواحد مع الدوران لأسفل، محاذياً له. العدد الكمومي الرابع، عدد الكم الدوراني (ms) يصف هاتين الحالتين المختلفتين لدوران الالكترون. يحتوي رقم الكم الدوراني على قيمتين محتملتين، −1/2 (الدوران للأعلى) و+1/2 (الدوران للأسفل). يصف دوران الإلكترون الحالة الحقيقة لـ "دوران" أو "غزل الالكترون. " كل إلكترون يعمب كمغناطيس صغير أو جسم دوّار صغير ذي قوة دفع زاوي، أو كحلقة ذات تيار كهربائي، حتى مع أنه لا يمكن ملاحظة هذا الدوران أو التيار من حيث الإحداثيات المكانية. إن حجم الدوران الإلكتروني الإجمالي يمكن أن يكون له قيمة واحدة فقط، ولا يمكن للإلكترونات أن “تغزل” إلا في واحدة من حالتين كمّيتين. ويُطلق على إحداها حالة &ألفا، حيث يكون مكون z في الدوران في الاتجاه الإيجابي للمحور z-axis. ويتوافق هذا مع رقم كمية الغزل ms = +1/2. ويطلق على الآخر اسم الحالة &بيتا، حيث يكون مكون z في الدوران في الاتجاه السلبي و ms = −1/2.أي إلكترون، بغض النظر عن المستوى الذري الذي يقع فيه، يمكن أن يكون له قيمة واحدة فقط من هاتين القيمتين لرقم الكم الدوار. تختلف طاقات الإلكترونات التي تحتوي على دمغات مختلفة إذا تم تطبيق مجال مغناطيسي خارجي. يتم وصف الإلكترون في الذرة بالكامل بأربعة أرقام كومية:n, l, ml, و ms. وتحدد الأعداد الكمومية الثلاثة الأولى المدار، وهي تعتمد على بعضها البعض، في حين أن العدد الكمومي الرابع مستقل عن الأعداد الكمومية الأخرى حيث يصف خاصية إلكترون فعلية تسمى الغزل. قام عالم الفيزياء النمساوي ولفغانغ باولي (جائزة نوبل في الفيزياء: 1945) بصياغة مبدأ عام يعطي المعلومة الأخيرة التي نحتاج إليها لفهم السلوك العام للإلكترونات في الذرات. يمكن صياغة مبدأ استبعاد باولي كما يلي: لا يمكن أن يكون لإلكترونين في نفس الذرة نفس المجموعة بالضبط من جميع الأعداد الكمومية الأربعة. ما يعنيه هذا هو أن إلكترونين يمكنهما مشاركة نفس المستوى (نفس مجموعة الأعداد الكمومية n, l, و ml) فقط إذا كانت لأعدادهم الكمومية الدوارة قيم مختلفة. بما أن عدد الدوران الكمي (ms) يمكن أن يحتوي فقط على قيمتين + 1/2 و -1/2، فلا يمكن أن يشغل أكثر من إلكترونين نفس المستوى (وإذا كان هناك إلكترونان في نفس المستوى، فيجب أن يكون لهما مغزلان متقابلان). وبالتالي، يمكن ملء أي مدار ذري بواسطة صفر أو واحد أو اثنين من الإلكترونات فقط. 
 يمثل نمط المخطط المداري لتكوين الإلكترون كل مستوى داخل هيكل فرعي مشغول في شكل مربع أو خط وكل إلكترون في شكل سهم. المخطط المداري للهيدروجين، الذي يبلغ تكوين الإلكترون 1s1, هو:<img alt="Figure1" src="https://www.jovecore.com/CDNSource/lessons/984/984Image_1.png" style="height: 40px;" />يشير سهم لأعلى إلى نصف دورة زائد أو دورة جانبية، ويشير سهم لأسفل إلى نصف دورة أو دورة دوارة. ولذلك فإن المخطط المداري للهيدروجين يحتوي على سهم واحد لأعلى. التكوين الإلكتروني للهليوم هو 1s2. يحتوي الإلكترونان على ثلاثة أعداد كمومية متطابقة، حيث أنهما ينتميان إلى نفس الحاوية الواقية والقشرة الفرعية. أرقام كمية الغزل الخاصة بهم مختلفة، وفقاً لمبدأ استبعاد باولي. تسمى الإلكترونات ذات المغازل المتعاكسة بالمتقارنة إذا كانت تشغل نفس المدار. <img alt="Figure2" src="https://www.jovecore.com/CDNSource/lessons/984/984Image_2.png" style="height: 40px;" />تم اقتباس هذا النص من <a 6-3-development-of-quantum-theory=" books=" chemistry-2e=" href=" https:=" openstax.org=" pages="">Openstax, Chemistry 2e, Section 6.3: Development of Quantum Theory. </a>

يسمى ترتيب الإلكترونات في مدارات الذرة بتكوين الإلكترون. نصف تكوين الإلكترون برمز ...

Education

JoVE Core

Chemistry

الكيمياء

واحد

Electronic Structure of Atoms

البنية الإلكترونية للذرات

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

electron spin and orbital pairing

Electron spin and orbital pairing explain why only two electrons can fit in one atomic orbital. Electron configuration describes how electrons are arranged in an atom’s orbitals. It is written with three parts: the principal quantum number, n, the orbital type, or subshell, and a superscript that shows how many electrons are in that subshell. For example, 2p4 means four electrons in a p subshell with n = 2, and 3d8 means eight electrons in a d subshell with n = 3.

The three quantum numbers describe orbitals well, but they do not explain every experimental result. In the 1920s, very high-resolution hydrogen spectra showed fine structure, where some lines split into two close peaks instead of one. This suggested that electrons in the same orbital can still have small energy differences. Samuel Goudsmit and George Uhlenbeck proposed a fourth quantum number to explain this behavior. They called it the spin quantum number, ms.

An electron can have two spin states in an external magnetic field. One state is spin up, which aligns with the magnetic field, and the other is spin down, which points against it. The spin quantum number has only two values, +1/2 and -1/2. These are also called the alpha and beta states. Electron spin is an intrinsic property, so each electron behaves like a tiny magnet, even though this motion cannot be observed in normal space.

A complete electron description uses four quantum numbers: n, l, ml, and ms. The first three quantum numbers define the orbital and depend on one another. The spin quantum number is independent because it describes the electron’s spin. Austrian physicist Wolfgang Pauli used this idea to state the Pauli exclusion principle. It says that no two electrons in the same atom can have the same set of all four quantum numbers.

This principle means that two electrons may share the same orbital only if their spin quantum numbers are different. Because ms has only two possible values, no more than two electrons can occupy one orbital. An atomic orbital can therefore hold zero, one, or two electrons. In orbital diagrams, each orbital is shown as a box or line and each electron as an arrow. A hydrogen atom with configuration 1s1 has one upward arrow, which means one spin-up electron.

Helium has the configuration 1s2. Its two electrons share the same shell and subshell, so they have three identical quantum numbers. They differ in spin, which follows the Pauli exclusion principle. Electrons with opposite spins in the same orbital are called paired.

Electron Spin and Orbital Pairing

the wave nature of light

Measuring Light with Wavelength and Frequency

Light can be described as an electromagnetic wave, and its behavior helps explain many patterns seen in science. For centuries, scientists have tried to understand light. Newton used lenses and prisms to show that white light is made of the colors of the rainbow mixed together. He explained light as tiny particles moving at high speed. Other scientists, including Christiaan Huygens, showed that reflection and refraction could also be explained by treating light as a wave. At the time, people...

the electromagnetic spectrum

Electromagnetic Waves: Uses Across the Spectrum

The electromagnetic spectrum includes all electromagnetic radiation arranged by frequency and wavelength. Visible light is only a small part of it, and each color of visible light has its own frequency and wavelength. Different parts of the spectrum also use different units. Radio waves are usually measured in MHz, while the visible range is often measured in nm or angstroms. The spectrum is organized from radio waves to gamma rays as frequency increases and wavelength decreases. Radio waves...

interference and diffraction

Wave Patterns from Light and Slits

Light can form wave patterns through interference and diffraction. When two electromagnetic waves meet with their peaks and troughs lined up, they combine into a larger wave. This is constructive interference, and the waves are in phase. When a peak of one wave meets a trough of the other, the waves reduce each other. This is destructive interference, and the result has a much lower amplitude. Diffraction is another wave behavior. When light passes through a slit that is about the same size as...

photoelectric effect

Why Light Ejects Electrons from Metals

Light can eject electrons from a metal surface when it has the right frequency. This process is called the photoelectric effect. Each metal has its own threshold frequency, which is the minimum light frequency needed to free electrons. Light below the threshold frequency cannot cause emission, even if it is very bright. When the light frequency is above the threshold, electrons are ejected. In that case, the number of electrons released is directly proportional to the intensity, or brightness,...

the bohr model

Bohr’s Quantized Atomic Orbits

Bohr’s quantized atomic orbits explain why hydrogen atoms can stay stable. Early in the twentieth century, Ernest Rutherford and his colleagues described atoms as tiny dense nuclei with lighter electrons moving around them. This picture was called the planetary model because it compared the atom to a miniature solar system, with electrons orbiting the nucleus like planets around the sun. The simplest atom is hydrogen. It has one proton in the nucleus and one electron moving around it. In the...

emission spectra

Line Spectra from Heated Gases

Line spectra are produced when heated gases give off light at specific wavelengths. In contrast, hot solids, liquids, or condensed gases radiate excess energy as a continuous spectrum. That spectrum contains an unbroken range of wavelengths. A gas at low partial pressure can produce a line spectrum when it is excited by an electric current or heated. Fluorescent light bulbs and neon signs work in this way. Each element has its own characteristic set of lines, and molecules can also produce...

the de broglie wavelength

Electron Waves and Standing Orbits

Electron waves and standing orbits explain how tiny particles can behave like waves. Large objects in the macroscopic world, like a billiard ball on a table, follow classical physics. A ball keeps moving in a straight line unless it hits another ball or a force such as friction acts on it. It also has a well-defined position, velocity, and momentum, where momentum is mass times velocity. Waves behave differently from macroscopic particles. When waves interact, they can form interference...

the uncertainty principle

Electron Position and Momentum Limits

Heisenberg’s uncertainty principle sets a limit on how precisely we can know an electron’s position and momentum at the same time. Momentum is the motion of a particle, and the two measurements affect each other. If the momentum is known more accurately, the position becomes less certain, and the reverse is also true. Heisenberg described this limit with an equation that uses Planck’s constant. The equation shows the smallest possible uncertainty for position and momentum together. It explains...

the quantum-mechanical model of an atom

Electron Orbitals in Quantum Mechanics

Quantum mechanics explains how electrons behave in atoms using waves and probability. Erwin Schrödinger built on de Broglie’s idea that an electron in hydrogen could act like a circular standing wave instead of moving in fixed circular paths. He then derived the Schrödinger equation, which became a major step in modern atomic theory. When Schrödinger applied his equation to hydrogen-like atoms, it matched Bohr’s energy expression and the Rydberg formula for hydrogen spectra. He described...

quantum numbers

Electron Orbitals and Spin

Electron orbitals are described by quantum numbers that show where an electron is most likely to be found around the nucleus. These numbers come from the quantum mechanical model, which is based on solutions of the Schrödinger equation. They also help explain why electron energy comes in set values instead of changing smoothly. The principal quantum number, n, labels the energy level. It can be 1, 2, 3, and so on, and higher n values usually mean higher electron energy. This number also tells...

atomic orbitals

Electron Regions in Atomic Orbitals

Electron regions in atomic orbitals show where an electron is most likely to be found in an atom. These three-dimensional regions are often drawn as boundary surfaces around the densest part of the cloud. The shape of an orbital depends on the angular momentum quantum number, l. This value can range from 0 to n - 1, where n is the principal quantum number. For n = 1, only l = 0 is allowed. For n = 2, both l = 0 and l = 1 are allowed. Orbitals with the same value of l form a subshell. The l =...

the pauli exclusion principle

Electron spin and orbital pairing explain why only two electrons can fit in one atomic orbital. Electron configuration describes how electrons are arranged in an atom’s orbitals. It is written with three parts: the principal quantum number, n, the orbital type, or subshell, and a superscript that shows how many electrons are in that subshell. For example, 2p4 means four electrons in a p subshell with n = 2, and 3d8 means eight electrons in a d subshell with n = 3. The three quantum numbers...

the energies of atomic orbitals

Shielding and Orbital Penetration

Shielding and orbital penetration help explain why electrons in an atom have different energies. Electrons are attracted to the positive nucleus, but they also repel one another in atoms with more than one electron. The strength of these forces depends on the charge and the distance between the particles. Opposite charges attract, like charges repel, and the force gets weaker as the particles move farther apart. An electron that stays closer to the nucleus is held more tightly. That means...

the aufbau principle and hund's rule

Electron Filling Order in Atomic Orbitals

Electron filling order in atomic orbitals follows the aufbau principle and Hund's rule. To write an electron configuration, we build atoms in order of atomic number. Starting with hydrogen and moving across the periods of the periodic table, one proton is added to the nucleus and one electron is placed into the correct subshell. This process describes the ground-state electron configurations of the elements. The aufbau principle comes from the German word aufbau, which means "to build up." It...

electron configuration of multielectron atoms

electron-configuration-of-multielectron-atoms

Valence Electrons and Noble Gas Shorthand

Valence electrons and noble gas shorthand help show how electrons are arranged in multielectron atoms. Sodium, the alkali metal with atomic number 11, has one more electron than neon. That extra electron goes into the lowest-energy subshell available, the 3s orbital, so sodium has the configuration 1s2 2s2 2p6 3s1. Electrons in the outermost shell, where n is highest, are called valence electrons. Electrons in the inner shells are called core electrons. Because core electrons often match a...

key terms and concepts

Learn how electron spin, quantum numbers, and orbital pairing explain why each atomic orbital holds at most two electrons in high school chemistry.

Electron Spin and Orbital Pairing | JoVE K12

chemistry

JoVE Core Chemistry brings general chemistry concepts to life using concise and easy-to-understand animated video lessons. Plus, in the scientist-in-action videos, we demonstrate classical and original research experiments performed in today's laboratories worldwide.

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NC K-12 Science Standard Course of Study

9-12

Matter and its Interactions

PS.Chm.1.3

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Ohio’s Learning Standards and Model Curriculum

Structure And Properties Of Matter

Atomic structure

Tennessee Academic Standards

Matter and Its Interactions

CHEM1.PS1.12

Virginia  Standards of Learning

HIgh School

CH.2

CH.2.e

Physical Science

PS.2

PS.2.a

CHEM.6

CHEM.6.B

Next Generation Science Standards

HS-PS1-1

Florida Department of Education

SC.912.P.8

SC.912.P.8.5

SC.912.P.10

SC.912.P.10.9

IPC.7.D

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New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-7.

Georgia Standards of Excellence

SC1.

electron-configuration-and-chemical-properties

Electron Configuration and Chemical Properties

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 ...

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 ...

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, ...

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 ...

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 ...

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 ...

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, ...

Bonding in Metals

Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Dr&#xFC;de called the ...

Model basic atomic structure and relate an element's atomic structure to its bonding, reactivity, and placement on the Periodic Table.

IPC.7.A

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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 ...

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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 ...

Alkali Metals

Group 1 elements are soft and shiny metallic solids. They are malleable, ductile, and good conductors of heat and electricity. The melting points of the ...

Halogens

Group 17 elements, known as halogens, are nonmetals. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine a solid. ...

Noble Gases


The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name &ldquo;noble&rdquo; because they were ...

Use patterns within the Periodic Table to predict the relative physical and chemical properties of elements.

IPC.7.B

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 ...

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 ...

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 ...

Melting Points

Melting Points in Organic Chemistry
The melting point of a compound is the temperature at which the solid phase transitions into the liquid phase at a ...

Boiling Points

Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA

	Preparation of the LaboratoryExpand
	Here, we show the laboratory preparation ...

Explain how physical and chemical properties of substances are related to their usage in everyday life such as in sunscreen, cookware, industrial applications, and fuels.

IPC.7.C

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 ...

Metal Flame Emission

Metal Flame Emission
Flame testing is an analytical technique where a sample is placed in a flame, and the characteristic flame color is used to identify ...

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 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 ...

Explain how electrons can transition from a high energy level to a low energy state, emitting photons at different frequencies for different energy transitions.

Science concepts. The student knows that relationships exist between the structure and properties of matter. The student is expected to:

Electron Spin and Orbital Pairing

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