Name: electron orbitals and spin
Uploaded: 2020-09-03T13:38:27.000Z
Duration: 2 min 43 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Physical Science

Study Of Matter

Atoms

Quantum Numbers

Chaque électron est décrit par quatre nombres quantiques, dont trois ont des valeurs interdépendantes. Ces trois nombres quantiques définissent où l'électron est le plus susceptible d'être situé dans l'espace. Le nombre quantique principal, n, indique le niveau d'énergie auquel appartient un électron.n peut prendre les valeurs entières de un, deux, trois, et ainsi de suite. Plus la valeur de n est grande, plus l'électron est éloigné du noyau. Le moment angulaire, ou azimutal, nombre quantique, l, décrit la forme de l'orbitale que l'électron occupe, qui est liée au moment angulaire de l'électron.l peut avoir des valeurs entières de 0 à n-1 pour chaque valeur de n. Quand n est un, l est zéro. Lorsque n est deux, l a deux valeurs possibles zéro et un.Lorsque n est trois, l peut être zéro, un ou deux. Le nombre de valeurs l possibles indique le nombre de groupes d'orbitales de forme différente, ou de sous-couches, au nième niveau d'énergie. Les sous-coquilles sont désignées par des lettres associées aux valeurs de l.Zéro, un, deux et trois correspondent respectivement aux orbitales s, p, d et f. Ceux-ci seront discutés dans la prochaine leçon. Le nombre quantique magnétique, m_l, décrit l'orientation dans l'espace de l'orbitale de l'électron occupe, qui est également lié à l'électron du moment angulaire.m_l peut avoir n'importe quelle valeur entière entre-l et l, y compris zéro. Le nombre d'orientations pour un sous-shell donné est égal à 2l 1. Lorsque n est deux, il y a deux sous-shells, car l peut être zéro ou un.Ce sont les sous-shells 2s et 2p, respectivement. Le sous-shell 2p a trois orbitales 2p, car il y a trois valeurs pour ml:1, 0 et 1. Le quatrième nombre quantique, m_s, est le nombre quantique de spin.Les électrons tournent des charges et se comportent comme de minuscules aimants à barres. Les deux mouvements de rotation possibles pour l'électron sont dans le sens horaire, indiqué par un m_sof 1/2, et dans le sens antihoraire, indiqué par un m_s de 1/2.

nombres quantiques

On dit que l'énergie d'un électron dans un atome est quantifiée, c'est-à-dire qu'elle ne peut être égale qu'à certaines valeurs déterminées et peut sauter d'un niveau d'énergie à un autre, mais ne peut pas faire des transitions de façon régulière ou rester entre ces niveaux. 
 
 Les niveaux d'énergie ont une valeur n qui leur correspond, où n = 1, 2, 3, etc. En général, l'énergie d'un électron dans un atome est plus grande pour les valeurs plus élevées de n. Ce nombre, n, est appelé le nombre quantique principal. Le nombre quantique principal définit la position du niveau d'énergie. C'est essentiellement la même idée que pour le n dans la description de l'atome de Bohr. Un autre nom pour le nombre quantique principal est le numéro de la couche. 
 
 Le modèle mécanique quantique précise la probabilité de trouver un électron dans l'espace tridimensionnel autour du noyau et il est basé sur les solutions de l'équation de Schrödinger. 
 
 Un autre nombre quantique est l, le nombre quantique secondaire (du moment angulaire). Il s'agit d'un nombre entier qui peut prendre les valeurs, l = 0, 1, 2, …, n – 1. Cela signifie qu'une orbitale dont n = 1 ne peut avoir qu'une seule valeur de l, l = 0, alors que n = 2 permet l = 0 et l = 1, et ainsi de suite. Alors que le nombre quantique principal, n, définit la taille et l'énergie générales de l'orbitale, le nombre quantique secondaire l spécifie la forme de l'orbitale. Les orbitales ayant la même valeur de l définissent une sous-couche. 
 
 Les orbitales dont em>l = 0 sont appelées les orbitales s, et elles constituent les sous-couches s. La valeur l = 1 correspond aux orbitales p. Pour un n donné, les orbitales p constituent une sous-couche p (par exemple, 3p si n = 3). Les orbitales dont l = 2 sont appelées les orbitales d, suivies des orbitales f, g, et h pour l = 3, 4 et 5. 
 
 Le nombre quantique magnétique, ml, précise l'orientation spatiale relative d'une orbitale particulière. En général, ml peut être égal à &ndashl, –(l – 1), …, 0, …, (l – 1), l. Le nombre total d'orbitales possibles avec la même valeur de l (c'est-à-dire dans la même sous-couche) est de 2l + 1. Ainsi, il y a une orbitale s dans une sous-couche s (l = 0), il y a trois orbitales p dans une sous-couche p (l = 1), cinq orbitales d dans une sous-couche d (l = 2), sept orbitales f dans une sous-couche f (l = 3), et ainsi de suite. Le nombre quantique principal définit la valeur générale de l'énergie électronique. Le nombre quantique du moment angulaire détermine la forme de l'orbitale. Et le nombre quantique magnétique précise l'orientation de l'orbitale dans l'espace. 
 
 Bien que les trois nombres quantiques traités dans les paragraphes précédents fonctionnent bien pour décrire les orbitales électroniques, certaines expériences ont montré qu'ils ne suffisaient pas à expliquer tous les résultats observés. Il a été démontré dans les années 1920 que lorsque les spectres de raies de l'hydrogène sont examinés à une résolution extrêmement haute, certaines raies ne sont en fait pas des pics simples mais plutôt des paires de raies très peu espacées. C'est la soi-disant structure fine du spectre, et cela implique qu'il y a de petites différences supplémentaires dans les énergies des électrons, même lorsqu'ils sont situés sur la même orbitale. Ces observations ont amené Samuel Goudsmit et George Uhlenbeck à proposer que les électrons aient un quatrième nombre quantique. Ils ont appelé cela le nombre quantique de spin ou s.
 
 Les trois autres nombres quantiques, n, l et ml sont des propriétés d'orbitales atomiques spécifiques qui définissent également dans quelle partie de l'espace un électron est le plus susceptible d'être localisé. Les orbitales sont le résultat de la résolution de l'équation de Schrödinger pour les électrons dans les atomes. 
 
 Le quatrième nombre quantique, ms, est le nombre quantique de spin. Les électrons sont des charges tournantes et ils se comportent comme de minuscules barreaux aimantés. Les deux mouvements de spin possibles de l'électron sont dans le sens d'une aiguille d'une montre et dans le sens inverse d'une aiguille d'une montre. Pour un électron dans une orbitale, ces deux possibilités sont indiquées par des nombres quantiques de spin, +1/2 pour un spin dans le sens d'une aiguille d'une montre et −1/2 pour un spin dans le sens inverse. C'est le seul nombre quantique ayant des valeurs de nombres non entiers. 
 
 Ce texte est adapté de <a href="https://openstax.org/books/chemistry-2e/pages/6-3-development-of-quantum-theory">Openstax, Chimie 2e, Section 6.3 : Développement de la théorie quantique</a>.

Nombres quantiques

On dit que l’énergie d’un électron dans un atome est quantifiée ; c’est-à-dire qu’il ne peut être égal qu’à certaines valeurs spécifiques et peut sauter d’une énergie ...

Education

Enseignement

JoVE Core

Chemistry

Chimie

Electronic Structure of Atoms

Structure électronique des atomes

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

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 you the general location of the energy level. It is the same idea as the n value in the Bohr atom model, and it is also called the shell number.

A second number, l, is the secondary or angular momentum quantum number. It can take values from 0 to n - 1. For example, when n = 1, only l = 0 is allowed. When n = 2, l can be 0 or 1. This number gives the shape of the orbital, and orbitals with the same l value make up a subshell.

The l values also match the familiar orbital names. Orbitals with l = 0 are s orbitals, and they form s subshells. The value l = 1 corresponds to p orbitals, so if n = 3, the p orbitals belong to the 3p subshell. The orbitals with l = 2 are called d orbitals, followed by f, g, and h orbitals for l = 3, 4, and 5.

The magnetic quantum number, m l, tells the orientation of an orbital in space. Its possible values run from -l to +l, including 0. This means the number of orbitals in a subshell is 2l + 1. So an s subshell has one orbital, a p subshell has three, a d subshell has five, and an f subshell has seven.

The first three quantum numbers describe orbitals well, but high-resolution hydrogen spectra showed more detail. In the 1920s, scientists found that some spectral lines split into pairs of close lines. This fine structure suggests small energy differences for electrons even in the same orbital. Samuel Goudsmit and George Uhlenbeck used this result to propose a fourth quantum number.

They called the fourth number the spin quantum number, m s. Electrons behave like tiny bar magnets and can spin in two ways: clockwise or counterclockwise. These two possibilities are written as +1/2 and -1/2. Unlike the other quantum numbers, the spin quantum number is not an integer.

Electron Orbitals and Spin

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 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

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 n, l, m l, and m s describe electron energy levels, orbital shape, orbital orientation, and electron spin in atoms.

Electron Orbitals and Spin | JoVE K12

chemistry

JoVE Core Chimie anime les concepts de chimie générale en utilisant des leçons vidéo concises et faciles à comprendre. De plus, nos vidéos de scientifiques à l'action présentent des expériences de recherche, classiques ou insolites, effectuées dans des laboratoires modernes du monde entier.

Structure And Properties Of Matter

Atomic structure

Tennessee Academic Standards

High School

Matter and Its Interactions

CHEM1.PS1.12

Virginia  Standards of Learning

HIgh School

CH.2

CH.2.e

PS.2

PS.2.a

Physics

PH.9

PH.9.b

Arizona Science Standards

HS.P1

HS.P1U1.1

Texas Essential Knowledge and Skills

CHEM.6

CHEM.6.B

Florida Department of Education

SC.912.P.10

SC.912.P.10.9

PHYS.9

PHYS.9.C

PHYS.9.D

Chemistry and Physics

IPC.7

IPC.7.E

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-7.

HS. Waves and Electromagnetic Radiation

HS-PS4-3.

Georgia Standards of Excellence

SC1.

electron-configuration-and-chemical-properties

Electron Configuration and Chemical Properties

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 ...

physical-and-chemical-properties-of-matter

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 ...

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 ...

Molecules and Compounds

Atoms and Molecules

Everything in the universe is made up of matter, and matter is composed of a combination of elements. An atom is the smallest unit of ...

Classification of Elements and Compounds

Pure substances consist of only one type of matter. A pure substance can be an element or a compound. An element consists of only one type of atom, while ...

What is Energy?

The universe is composed of matter in different forms, and all forms of matter contain energy. &#xA0;The different forms of energy on Earth originate from ...

Energy Basics

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.

Chemical changes and their accompanying ...

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, ...

surface-tension-capillary-action-and-viscosity

Surface Tension, Capillary Action, and Viscosity

Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded ...

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 ...

Vapor Pressure

When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules move randomly about, they will occasionally ...

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 ...

Heating and Cooling Curves

When a substance&#8212;isolated from its environment&#8212;is subjected to heat changes, corresponding changes in temperature and phase of the substance ...

Phase Diagrams

A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. ...

• Heterogeneous vs. homogeneous 
• Properties of matter 
• States of matter and its changes

Content elaboration: Matter was introduced in the elementary grades and the learning progression continued through middle school to include differences in the physical properties of solids, liquids and gases. Elements, compounds, mixtures, molecules, kinetic and potential energy and the particulate nature of matter were introduced. Content in Chemistry (e.g., electron configuration, molecular shapes, bond angles) will build on concepts in this course. Matter can be classified in broad categories, such as homogeneous and heterogeneous, according to its composition or by its chemical properties (e.g., reactivity, flammability, pH) and physical properties (e.g., color, solubility, odor, hardness, density, conductivity, melting point and boiling point, viscosity, malleability). Solutions are homogeneous mixtures of a solute dissolved in a solvent. The amount of a solid solute that can dissolve in a solvent generally increases as the temperature increases since the particles have more kinetic energy to overcome the attractive forces between them. Water is often used as a solvent since so many substances will dissolve in water. Aqueous solutions can be classified as acidic (below 7 on the pH scale), neutral (7 on the pH scale), or basic (above 7 on the pH scale), but the discussion of hydroxide and hydrogen ions as they relate to the pH scale is reserved for Chemistry. Physical properties can be used to separate the substances in mixtures, including solutions. Phase changes can be represented by graphing the temperature of a sample vs. the time it has been heated. Investigations include collecting data during heating, cooling and solid-liquid-gas phase changes. At times, the temperature will change steadily, indicating a change in the motion of the particles and the kinetic energy of the substance. However, during a phase change, the temperature of a substance does not change, indicating there is no change in kinetic energy. Since the substance continues to gain or lose energy during phase changes, these changes in energy are potential and indicate a change in the position of the particles. When heating a substance, a phase change will occur when the kinetic energy of the particles is great enough to overcome the attractive forces between the particles; the substance then melts or boils. [cite: 91, 92] Conversely, when cooling a substance, a phase change will occur when the kinetic energy of the particles is no longer great enough to overcome the attractive forces between the particles; the substance then condenses or freezes. [cite: 92, 93] Phase changes are examples of changes that can occur when energy is absorbed from the surroundings (endothermic) or released into the surroundings (exothermic). When thermal energy is added to a solid, liquid or gas, most substances increase in volume because the increased kinetic energy of the particles causes an increased distance between the particles. This results in a change in density of the material. Generally, solids have greater density than liquids, which have greater density than gases due to the spacing between the particles. [cite: 96, 101] The density of a substance can be calculated from the slope of a mass vs. volume graph. Differences in densities can be determined by interpreting mass vs. volume graphs of the substances. Students should be able to calculate mass, volume or density, given two of the three values.

Classification of matter

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 ...

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 ...

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 ...

The Bohr Model

Following the work of Ernest Rutherford and his colleagues in the early twentieth century, the picture of atoms consisting of tiny dense nuclei surrounded ...

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 ...

The Quantum-Mechanical Model of an Atom

Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as being a circular standing wave instead of ...

It is said that the energy of an electron in an atom is quantized; that is, it can be equal only to certain specific values and can jump from one energy ...

• Models of the atom (components)
• Ions (cations and anions)
• Isotopes

Content elaboration: Content introduced in middle school, where the atom was introduced as a small, indestructible sphere, is further developed in this course. Over time, technology was introduced that allowed the atom to be studied in more detail. The atom is composed of protons, neutrons and electrons that have measurable properties, including mass and, in the case of protons and electrons, a characteristic charge. An atom is empty space with a very small positively charged nucleus. The nucleus is composed of protons and neutrons. The electrons move about in the empty space that surrounds the nucleus. Although current understanding goes beyond the Bohr Model, it can still be used to represent the atom and develop the idea of valence electrons. Experimental evidence that led to the development of historic atomic models is reserved for Chemistry. All atoms of a particular element have the same atomic number; an element may have different isotopes with different mass numbers. [cite: 112, 113] Atoms may gain or lose valence electrons to become anions or cations. Atomic number, mass number, charge and identity of the element can be determined from the numbers of protons, neutrons and electrons. Atomic mass calculations and explanations about configuration of electrons and how atomic spectra are produced are reserved for Chemistry.

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 ...

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 ...

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 ...

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 ...

• Periodic law 
• Representative groups

Content elaboration: Content from the middle school level, specifically the properties of metals, nonmetals and metalloids and their positions on the periodic table, is further expanded in this course. The periodic table was arranged so that elements with similar chemical and physical properties are in the same group or family. When elements are listed in order of increasing atomic number, the same sequence of properties appears over and over again; this is the periodic law. [cite: 120, 121] Trends in simple observable properties, like density or melting point, can be examined within families or groups on the periodic table. These trends allow scientists to make predictions about new elements. Metalloids are elements that have some properties of metals and some properties of nonmetals. Metals, nonmetals, metalloids, periods and groups or families including the alkali metals, alkaline earth metals, halogens and noble gases can be identified by their position on the periodic table. Elements in Groups 1, 2 and 17 have characteristic ionic charges that will be used in this course to predict the formulas of compounds. Other trends in the periodic table (e.g., atomic radius, electronegativity, ionization energies) are reserved for Chemistry.

Periodic trends of the elements

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 ...

• Bonding (ionic and covalent)
• Nomenclature

Content elaboration: Middle school content introduced the concept that compounds are composed of atoms of two or more different elements joined together chemically. In this course, the chemical joining of atoms is studied in more detail. Atoms may be bonded together by losing, gaining or sharing valence electrons to form molecules or three-dimensional lattices. An ionic bond involves the attraction of two oppositely charged ions, typically a metal cation and a nonmetal anion formed by transferring electrons between the atoms. An ion attracts oppositely charged ions from every direction, resulting in the formation of a three-dimensional lattice. Covalent bonds result from the sharing of electrons between two atoms, usually nonmetals. Covalent bonding can result in the formation of structures ranging from small individual molecules to three-dimensional lattices (e.g., diamond). The bonds in most compounds fall on a continuum between the two extreme models of bonding: ionic and covalent. Using the periodic table to determine ionic charge, formulas of ionic compounds containing elements from groups 1, 2, 17, hydrogen and oxygen can be predicted. Given a chemical formula, a compound can be named using conventional systems that include Greek prefixes where appropriate. Prefixes will be limited to represent values from one to 10. Given the name of an ionic or covalent substance, formulas can be written. Naming organic molecules is beyond this grade level and is reserved for an advanced chemistry course. Prediction of bond types from electronegativity values, polar covalent bonds, and writing formulas/naming compounds that contain polyatomic ions or transition metals are reserved for Chemistry.

Bonding and compounds

Electron Orbitals and Spin

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