Name: electron regions in atomic orbitals
Uploaded: 2020-09-03T13:38:27.000Z
Duration: 2 min 44 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry and Physics

IPC.7

IPC.7.E

Atomic Orbitals

電子雲の中で 最も密度の高い領域 つまり電子が最も多く 存在する領域は 原子軌道で表されます 原子軌道の形は 角運動量量子数l によって決まります lの値は主量子数nに 基づいていることを 覚えておいてください nが1より大きい場合 複数の副量子数が存在します lの各値はs p d f軌道 のいずれかに対応します 最も低いエネルギーの軌道は 1-s軌道です これは球対称軌道です 1-s軌道の確率密度から 電子は原子核に存在する可能性が 高いことがわかります しかし 陽子と電子の間の 静電力を考えると これは可能性が低くなります 確率密度を半径rの 薄い球状の殻の 体積にかけると より精密なものになります 薄い球状の殻の中で 原子核からrの距離にある 電子が見つかる確率の合計が 放射状分布関数となります 水素の場合 原子核から 52.9ピコメートルの距離だけ 離れたところで 電子が見つかる確率が 最も高くなります したがって 水素の 1s原子軌道の形状は 半径52.9ピコメートルの 球形となります 2sと3sの原子軌道も 球形です これらの軌道はより大きく ノードを持っています ノードでは 電子が見つかる確率はゼロです nが2以上に等しい 主水準はまた3つの p軌道を含んでいます これらは 核にノードを持つ ローブ状のものです その配向は m-lの値で表されます 3つのp軌道は 互いに直交しています nが3以上の主準位には5つの d軌道があります クローバーリーフ形状の d軌道は 4つの電子密度の高い ローブと2つの垂直な結節面を 持っています d軌道のうちの1つは わずかに異なっています f軌道はより多くのローブと ノードを持っています これらの軌道は 4以上の 主レベルのnに対して 存在しています これらの軌道を重ね合わせると だいたい球状の 形が浮かび上がってきます これが 原子が一般的に 球体として表現される理由です

原子軌道

原子軌道とは、原子の中で電子が最も高い確率で存在する3次元領域のことです。動径分布関数は、原子核からrの距離にある薄い殻の中に電子が存在する確率の総和を示します。原子の軌道は、角運動量の量子数であるlで決まる明確な形をしています。軌道はしばしば境界面で描かれ、雲の最も密度の高い領域を囲んでいます。
 
 角運動量量子数は、値 l=0 、 1 、 2 、…n-1を取ることができる整数です。主量子数が 1 （ n=1）の軌道は l （ l=0 ）の値を 1 つだけ持つことができ、主量子数が 2 （ n = 2 ）の軌道は l = 0と l = 1 を許容します。 lと同じ値を持つ軌道は小軌道を定義します。 
 
 l=0 の軌道は s 軌道と呼ばれ、 s 小軌道を構成します。 l=1 は、 p 軌道に対応します。 特定の n に対して、 p 軌道は p 小軌道を構成します（つまり、 n= 3 の場合は 3 p ）。 l = 2 の軌道は d 軌道と呼ばれます。 l = 3 、 4 、および 5 の軌道はf、g、 hです。  
 
 最もエネルギーの低い軌道は、1s軌道です。これは球対称の軌道です。1s軌道の確率密度（ψ2）は、電子が原子核に存在する可能性が最も高いことを意味しています。しかし、陽子と電子の間の静電力を考慮すると、これは電子がどこに存在するかを正確に表すものではありません。動径分布関数は、確率密度に半径rの薄い球殻の体積を乗じて求められます。水素の1s軌道の動径分布関数は、原子核で0になり、52.9ピコメートルで最大になり、その後rが大きくなるにつれて小さくなります。
 
 ある軌道に位置する電子を見つける確率密度がゼロになる核からの距離があります。言い換えれば、この距離では、この軌道に対して波動関数ψの値がゼロになります。このようなrの値を動径節（節）と呼びます。1つの軌道における動径節の数はn – l – 1であり、n = 1の2s軌道では動径節は1つですが、3s軌道では動径節は2つです。
 
 n=2以上の各主準位には、3つのp軌道が存在します。3つのp軌道は、核に1つの節と2つの軌道胞を持っています。空間におけるp軌道の向きは、mlの値で表されます。3つのp軌道は相互に直交しています。高次のp軌道（3p、4p、5p、およびそれ以上）は、似たような形をしているが、サイズが大きく、半径方向に動径節が追加されています。 
 
 n=3以上の主準位には、5つのd軌道が存在します。これらの軌道のうち4つは、電子密度の高い4つの軌道胞を持つクローバーの形からなります。原子核で交差する2つの垂直な節平面があります。これらの節平面では、電子密度はゼロです。d軌道の1つはわずかに形が異なり、z軸方向に2つの軌道胞があり、xy平面上にドーナツ型の輪があります。n = 4以上の主準位には、7つのf軌道が含まれており、これらは複雑な形状をしています。これらの軌道は、d軌道よりも多くの動径節と軌道胞を持ちます。 
 
 <img alt="Figure1" src="https://www.jovecore.com/CDNSource/lessons/983/983Image 1.png" style="width: 700px;" />
 
 図 1 ：代表的な s、p、d、f軌道
 
 原子軌道の形の違いは、電子が存在する可能性のある3次元領域を表しています。すべての軌道を合わせるとほぼ球形になることから、原子は一般的に球形で表現されます。 
 
 この文章は <a href="https://openstax.org/books/chemistry-2e/pages/6-3-development-of-quantum-theory">、 Openstax, Chemistry 2e, Section 6.3: Development of Quantum Theory に基づいています。</a>

原子軌道は、電子が存在する可能性が最も高い原子内の3次元領域を表します。放射状の分布...

Education

JoVE Core

Chemistry

化学

Electronic Structure of Atoms

原子の電子構造

KEY TERMS AND CONCEPTS

主要用語と概念

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 = 0 orbitals are s orbitals, and they make up s subshells. The l = 1 orbitals are p orbitals, which form a p subshell such as 3p when n = 3. The l = 2 orbitals are d orbitals. The l = 3, 4, and 5 orbitals are called f, g, and h orbitals.

The lowest-energy orbital is the 1s orbital. It is spherically symmetric. The probability density, ψ², suggests that an electron is most likely found at the nucleus. But this does not fully match electron behavior. The radial distribution function gives the total probability of finding an electron at a distance r from the nucleus. It is found by multiplying the probability density by the volume of thin spherical shells.

For the 1s orbital of hydrogen, the radial distribution function is zero at the nucleus. It rises to a maximum at 52.9 picometers and then decreases as r increases. Some distances from the nucleus have zero probability density for a given orbital. These points are called radial nodes. The number of radial nodes is n - l - 1. A 2s orbital has one radial node, and a 3s orbital has two.

Each principal level with n = 2 or more contains three p orbitals. Each p orbital has two lobes and a node at the nucleus. Their orientation in space is described by m_l. The three p orbitals are mutually perpendicular. Higher p orbitals, such as 3p, 4p, and 5p, have the same general shape but are larger and contain additional radial nodes.

Principal levels with n = 3 or more contain five d orbitals. Four of them have a cloverleaf shape with four electron-dense lobes. They also have two perpendicular nodal planes that meet at the nucleus. The fifth d orbital has two lobes along the z-axis and a donut-shaped ring in the xy plane.

Principal levels with n = 4 and greater contain seven f orbitals. These orbitals have complex shapes with more nodes and lobes than d orbitals. Together, s, p, d, and f orbitals help explain why atoms are often drawn as spheres, even though the electron regions inside them have distinct shapes.

Electron Regions in Atomic Orbitals

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Explore electron regions in atomic orbitals, including s, p, d, and f shapes, radial nodes, and the radial distribution function for high school chemistry.

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chemistry

JoVE Core 化学は、簡潔で理解しやすいアニメーションビデオレッスンを使用して、一般的な化学の概念を生き生きとしたものにします。さらに、活動する科学者のビデオでは、現在世界中の実験室で行われている古典的そして独創的な研究・実験をお見せします。

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Electron Regions in Atomic Orbitals

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