Name: hydrogen emission lines
Uploaded: 2020-03-26T07:22:25.000Z
Duration: 3 min 53 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry and Physics

IPC.7

IPC.7.E

Balmer Series

원자와 분자는 에너지를 흡수하고 방출할 때 매우 흥미로운 행동을 보입니다. 원자의 전자는 전통적으로 바닥 상태라고 하는 가장 낮은 에너지 상태로 존재하며 n이 1과 동일한 것으로 표시됩니다. 그러나 원자가 에너지를 흡수하면 전자가 여기되어 더 높은 에너지 수준으로 이동합니다. 전자가 더 낮은 에너지 상태 또는 바닥 상태로 이완될 때 초과 에너지는 방출된 빛으로 방출됩니다.
이러한 에너지 상태에 대해 잘 알고 있을 것인데, 보어 모델(Bohr Model)은 원자를 껍질 또는 궤도에 궤도를 도는 전자가 있는 핵으로 설명합니다. 이러한 껍질은 에너지 준위와 동일하며 n으로 표시됩니다. 방출되는 빛의 파장은 높은 에너지 수준과 낮은 에너지 수준의 차이에 따라 달라집니다. 높은 에너지 방출 빛은 높은 에너지 준위에서 이완된 전자로 인해 발생하고, 낮은 에너지 방출 광은 낮은 에너지 수준에서 이완된 전자로 인해 발생합니다.
방출 스펙트럼은 다양한 파장에 걸쳐 방출되는 방사선을 측정한 것입니다. 순수한 원소 종의 경우, 방출 거동은 넓은 스펙트럼이 아닌 특정 파장의 선으로 나타납니다. 다른 원자는 다른 에너지 준위를 갖기 때문에 이러한 스펙트럼 선은 원소마다 다르며 여기될 때 이러한 전자가 에너지 상태 사이에서 만드는 전이에 따라 달라집니다. 예를 들어, 수소에 대한 6개의 명명된 스펙트럼 라인 시리즈가 있으며 그 중 하나가 Balmer 시리즈입니다.
스펙트럼 라인의 Balmer 시리즈는 전자가 n = 3보다 높은 에너지 준위에서 n = 2로 다시 전이할 때 발생합니다. Balmer 시리즈의 가시광선 스펙트럼은 410, 434, 486 및 656nm에서 스펙트럼 라인으로 나타납니다. h 알파 라인은 656nm에서 빨간색 선이며 n = 3에서 n = 2로의 전이로 인해 발생합니다. 청록색, 파란색 및 보라색 선은 각각 n = 4, 5 및 6에서 n = 2로 다시 내려가는 에너지 수준 전환에 해당합니다. 가시 범위 밖에서 추가 스펙트럼 라인을 측정할 수 있습니다.
Johann Balmer는 Balmer 공식을 사용하여 보이는 선을 정량화했습니다. 여기서 lambda는 관찰된 파장, c는 상수, n은 2의 낮은 에너지 준위, m은 더 높은 에너지 준위입니다. Balmer 방정식과 Bohr 모델의 조합은 다양한 원소의 스펙트럼 선을 설명하는 Rydberg 방정식을 제공합니다. 이 방정식에서 lambda는 기록된 파장이고 RH는 Rydberg 상수입니다. n-initial로 표시된 초기 수준은 전자가 여기하는 더 높은 에너지 수준을 나타내고 n final은 전자가 다시 이완되는 더 낮은 에너지 수준을 나타냅니다. Balmer 시리즈의 경우 nfinal = 2입니다.
이 실습에서는 수소, 헬륨 및 네온의 방출 스펙트럼을 측정 및 관찰하고 리드버그 방정식을 사용하여 스펙트럼 라인의 위치를 결정합니다.

발머 시리즈

보어 모델
닐스 보어(Niels Bohr)는 1913년에 수소 원자에 대한 모델을 제안했는데, 이 모델은 이산 에너지 상태가 핵 주위의 고정된 전자 궤도와 관련이 있다고 설명했습니다. 중요한 것은 원자는 전자가 정지 상태에 있는 동안 에너지를 방전할 수 없다는 것입니다. 전자는 에너지 상태를 변화시킴으로써만 에너지를 방출할 수 있습니다. 에너지 상태를 변경하려면 전자가 에너지를 흡수하거나 방출하여 한 궤도에서 다른 궤도로 이동해야 합니다. 이 변화는 흡수 또는 방출된 에너지가 두 상태 간의 차이와 같은 경우에만 발생할 수 있습니다. 궤도 사이에는 전자가 존재할 수 없습니다.
양자 번호 n은 서로 다른 에너지 상태를 표시하는 데 사용됩니다. 가장 낮은 에너지 상태는 n이 1과 같은 바닥 상태입니다. 여기 상태는 n이 2, 3, 4 등으로 레이블이 지정됩니다. 기저 상태의 전자가 에너지가 기저 상태와 두 번째 상태의 차이와 같은 광자를 흡수하면 전자는 여기가 되고 기저 상태에서 n= 2 여기 상태로 전환됩니다. 광자의 에너지가 바닥 상태와 세 번째 상태의 차이와 같으면 전자는 n=3 상태로 이동합니다.
Bohr의 모델에 따르면 n번째 수준에서 전자의 위치 에너지는 다음 방정식을 사용하여 계산할 수 있습니다.
<img src="/CDNSource/lm/labs/54/54_Concepts_1.jpg" alt="보어 모델 에너지 준위 공식, En=-Rhc/n², 전자 전이, 방정식과 관련." data-altupdatedat="1754907201000">
여기서 En은 위치 에너지, R은 리드베르크 상수(1.0974 ×10 7m-1), h는 플랑크 상수(6.62607004 × 10-34m 2·kg/s), c는 빛의 속도(~ 3 × 108m/s)입니다. 전자는 또한 자발적으로 바닥 상태 또는 다른 낮은 여기 상태로 돌아갈 수 있습니다. 이런 일이 발생하면 초과 에너지가 방출된 광자의 형태로 방출됩니다. 광자의 에너지는 높은 에너지 상태와 낮은 에너지 상태 사이의 에너지 차이와 같습니다. 그 에너지는 빛의 파장에 해당합니다. 각 유형의 원자는 서로 다른 에너지 준위를 갖기 때문에 각 전이에서 방출되는 빛은 각 원자마다 다릅니다. 혼합 분자 샘플의 경우, 방출된 빛은 연속 스펙트럼이라고 하는 다양한 파장을 포함합니다. 단일 원소의 원자를 포함하는 샘플의 경우, 방출된 빛은 특정 파장만 포함하며, 이는 프리즘에 의해 분리되면 별개의 선으로 볼 수 있습니다.
<h4>수소 원자</h4>
수소 원자를 구체적으로 살펴보면 전자의 여기는 이원자 분자 H2 의 결합을 분리하기에 충분한 에너지의 흡수를 필요로합니다. 분자를 분리하는 데 필요한 것보다 더 많은 에너지가 사용되기 때문에 수소 원자의 전자는 초과 에너지를 흡수하고 더 높은 에너지 수준으로 여기됩니다. 전자가 자발적으로 더 낮은 에너지 수준으로 돌아갈 때 빛이 방출되는데, 이는 여기 수준과 더 낮은 수준 사이의 에너지 차이에 해당합니다.
에너지 방출에 대해 논의할 때 높은 에너지 수준은 초기 수준 또는 ni로 간주되고 낮은 수준은 최종 수준 또는 nf로 간주됩니다. 방출되는 빛의 파장은 궁극적으로 두 수준 간의 에너지 차이에 따라 달라집니다.
순수한 수소 가스 샘플에서 방출 스펙트럼은 수소 원소에 특정한 개별 파장의 뚜렷한 선으로 나타납니다. 이러한 라인 중 일부는 전자기 스펙트럼의 가시 범위에 있고 일부는 자외선 또는 적외선 범위에 있습니다.
<h4>Balmer 시리즈</h4>
수소 원자 스펙트럼에서 보이는 일련의 선은 Balmer 계열이라고 명명됩니다. 이 일련의 스펙트럼 방출 라인은 전자가 높은 에너지 수준에서 n = 2의 낮은 에너지 수준으로 전환 할 때 발생합니다. 요한 발머(Johann Balmer)는 410.2 nm, 434.1 nm, 486.1 nm 및 656.3 nm에서 이러한 스펙트럼 선을 관찰했으며, 이는 각각 n=6, n=5, n=4 및 n=3 에너지 준위에서 n=2 준위로의 전이에 해당합니다.
Balmer는 Balmer 공식을 사용하여 방출된 빛의 이러한 파장을 연관시킬 수 있었습니다.
<img src="/CDNSource/lm/labs/54/54_Concepts_2.jpg" alt="파장 계산식 λ=C(m²/(m²-n²)), 분광학 분석을 위한 방정식." data-altupdatedat="1754907201000">
여기서, λ는 관측된 파장, C는 상수(364.50682 nm), n은 값이 2인 낮은 에너지 준위, m은 3보다 큰 값을 갖는 높은 에너지 준위입니다. 이 관찰은 Johannes Rydberg에 의해 개선되었으며, 여기서 R은 Rydberg 상수입니다.
<img src="/CDNSource/lm/labs/54/54_Concepts_3.jpg" alt="Rydberg 공식 방정식; 원자 분광법에서 스펙트럼선을 계산합니다." data-altupdatedat="1754907201000">
이 방정식은 방출된 빛을 설명하므로 높은 에너지 수준은 초기 수준 또는 ni로 간주되고 낮은 수준은 최종 수준 또는 nf로 간주됩니다. Balmer 급수의 경우nf는 2와 같습니다. 이 방정식은 Bohr 모델과 결합되어 전자를 초기 에너지 수준과 최종 에너지 수준인 ΔE 사이에서 이동시키는 데 필요한 에너지를 계산했습니다.
<img src="/CDNSource/lm/labs/54/54_Concepts_4.jpg" alt="에너지 준위 전이 방정식 \(\Delta E = Rhc(\frac{1}{n_f^2} - \frac{1}{n_i^2})\); 물리학 공식." data-altupdatedat="1754907201000">
나중에, 수소 원자에 대한 다른 스펙트럼 계열이 발견되었습니다. 예를 들어, Lyman 계열에는 자외선 영역의 에너지를 가진 방출선이 포함되어 있습니다.
<h4>참조</h4>
<ol>
	<li style="font-size:17px">Kotz, J.C., Treichel Jr, P.M., Townsend, J.R. (2012). 화학 및 화학 반응성. 캘리포니아 벨몬트 : Brooks / Cole, Cengage Learning.</li>
	<li style="font-size:17px">Silderberg, M.S. (2009). 화학: 물질과 변화의 분자적 성질. 매사추세츠주 보스턴: 맥그로 힐.</li>
</ol>

보어 모델
닐스 보어(Niels Bohr)는 1913년에 수소 원자에 대한 모델을 제안했는데, 이 모델은 개별 에너지 상태가 고정된 전자 궤도와 관련이 있다고 설명했습니다.

Education

JoVE Lab Manual

Chemistry

hydrogen emission lines

Hydrogen emission lines show how electrons move between fixed energy levels in the Bohr model. Niels Bohr proposed this model for the hydrogen atom in 1913. In this model, an electron can only occupy certain orbits, and it cannot exist between them.

These energy states are labeled with the quantum number n. The ground state is n = 1. Higher values, such as n = 2, 3, 4, and so on, are excited states. An electron changes state only by absorbing or emitting energy equal to the difference between two levels. A photon with the right energy can move an electron from one orbit to another.

Bohr’s model also links each energy level to a specific amount of potential energy. That value can be calculated with an equation that uses the Rydberg constant, Planck’s constant, and the speed of light. When an electron returns to the ground state or another lower excited state, it releases the extra energy as a photon. The photon energy matches the gap between the two states, so it also determines the wavelength of the emitted light.

Because each atom has its own energy levels, each element gives off its own pattern of light. A mixed sample can produce a continuous spectrum with many wavelengths. A pure sample of one element produces only certain wavelengths. When that light passes through a prism, it appears as separate lines instead of one smooth band.

Hydrogen shows this pattern clearly. Exciting hydrogen atoms requires enough energy to split the H2 molecule, and the extra energy excites the hydrogen electrons to higher levels. When those electrons drop back down, they emit light at wavelengths set by the energy difference between the initial level, n i, and the final level, n f. In pure hydrogen gas, this emission spectrum contains distinct visible, ultraviolet, and infrared lines that are unique to hydrogen.

The visible lines in hydrogen are called the Balmer series. They occur when an electron falls to n = 2 from a higher level. Johann Balmer observed lines at 410.2 nm, 434.1 nm, 486.1 nm, and 656.3 nm, which match transitions from n = 6, 5, 4, and 3 to n = 2. He described these wavelengths with the Balmer formula, where λ is the observed wavelength, C is a constant of 364.50682 nm, n is the lower level, and m is the higher level.

Later, Johannes Rydberg refined this idea using the Rydberg constant. For the Balmer series, the final level n f equals 2. The same relationship, combined with the Bohr model, can be used to calculate the energy change, ΔE, for electron transitions. Other hydrogen spectral series were later identified as well, including the Lyman series, which lies in the ultraviolet region.

Hydrogen Emission Lines

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galvanic cells

Battery Power from Redox Reactions

Electrochemistry studies how chemical change and electrical energy are linked. In this branch of chemistry, electrons move from one species to another. That movement can either produce current or be driven by an applied current. The main reaction in electrochemistry is the oxidation-reduction, or redox, reaction. A redox reaction has two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. These changes also shift the oxidation state of each substance. The...

electrolytic cells

Electroplating with Electrolytic Cells

Electrochemistry links electrical energy with chemical change, and electrolytic cells show how electricity can drive a nonspontaneous reaction. In these reactions, electrons move from one species to another. The key chemistry is a redox reaction, or oxidation-reduction reaction, which happens in two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. The substance that loses electrons is the reducing agent, and the substance that gains electrons is the...

proper lab notebook keeping

Recording a Reproducible Lab Experiment

Accurate lab notebook records are essential in science and organic chemistry labs. Without clear notes, descriptions, quantities, and observations, an experiment cannot be repeated or checked. Good record keeping supports reproducibility, which means other people can follow the same work and get similar results. A laboratory notebook is useful in school labs, research settings, and industry. It can also become a legal record when an idea, process, substance, or technique is patented and...

basic organic chemistry techniques

Organic Lab Glassware and Safe Handling

Organic chemistry labs use specific glassware, careful weighing steps, and controlled heating to keep reactions safe and accurate. Beakers and Erlenmeyer flasks are often used for mixing or holding solvents, but they are not meant for measuring volume unless only an approximate amount is needed. Volumetric glassware is used when a precise volume matters. This group includes graduated cylinders, volumetric pipettes, and volumetric flasks. A graduated cylinder is commonly used in the organic lab...

melting points

How Impurities Change Melting Points

Melting point helps identify an organic compound by showing the temperature where a solid turns into a liquid at 1 atmosphere of pressure. It is a physical property, like solubility, density, color, and electronegativity. Because the exact start of melting is hard to measure, the result is reported as a range. The lower end is when the first drops of liquid appear. The upper end is when the last solid has melted. Scientists compare this range with literature values to help identify a compound. <br...

boiling points

Boiling Point and Vapor Pressure

Boiling point and vapor pressure are key physical properties of a liquid. For a pure compound, the boiling point can help identify the substance. In experiments, the boiling point is usually recorded as a range because exact values are hard to measure and may differ by a few degrees from the literature value. Vapor pressure explains why a liquid boils. In a sealed container, some molecules at the liquid surface gain enough energy to escape into the gas phase. At the same time, some gas...

recrystallization

Purifying Crystals by Solubility

Purifying crystals by solubility is a key organic chemistry technique. Recrystallization uses differences in solubility to separate a desired solid product from starting materials, solvent, and impurities. It is one of the three standard purification methods, along with distillation and extraction. Solubility is the maximum amount of a substance that can dissolve in a fixed volume of solvent at a given temperature. Different solutes dissolve in different solvents, and their behavior can vary...

extraction

Separating Mixtures with Solvent Extraction

Solvent extraction is a common way to separate and isolate a target compound in organic chemistry. In this process, a solute moves from one phase to another so it can be separated from unreacted starting materials or impurities. Extraction is also useful when a product is dissolved in a reaction solvent that is hard to remove by evaporation, such as a solvent with a high boiling point. There are three main types of extraction. In solid-liquid extraction, the solute moves from a solid phase...

simple distillation

Separating Liquids by Boiling Point

Separating liquids by boiling point is the goal of distillation. A miscible mixture contains liquids that mix evenly, and it can be heated so that the more volatile liquid evaporates first. Volatility is a liquid’s tendency to vaporize, and boiling begins when bubbles form in the liquid phase. In a closed container, liquid and vapor can reach equilibrium, which means the rate of vaporization equals the rate of condensation. The pressure from the vapor above the liquid is called vapor pressure.

steam distillation

Steam Distillation and Low-Boiling Separation

Steam distillation is a separation method for temperature-sensitive organic compounds. It works best when the organic compound is immiscible in water, meaning the two liquids do not mix. The method helps remove the organic molecule from a non-volatile contaminant without using the higher temperatures needed for many other separations. In steam distillation, the immiscible mixture is heated until both water and the volatile organic compound distill together. The vapor rises to a condenser,...

thin-layer chromatography

TLC Separation by Polarity

Thin-layer chromatography (TLC) separates compounds in a mixture by polarity. It uses the same basic parts as other chromatography methods: a stationary phase, a mobile phase, and the solute. In TLC, the stationary phase is a thin coating on a plate instead of material packed into a column. The stationary phase in most TLC systems is polar silica gel, a form of silicon dioxide. Its surface has OH groups that can form hydrogen bonds. The sample is first spotted on a pencil start line with a...

column chromatography

Separating Mixtures by Polarity

Column chromatography separates compounds in an organic chemistry lab by using differences in physical properties. It is especially useful for microscale separations when less than 10 grams of material is available for analysis. The method can separate a mixture based on solubility, polarity, hydrophobicity, size, and charge. Any chromatography system has three main parts: the stationary phase, the mobile phase, and the sample mixture. In column chromatography, the stationary phase is usually...

hydrolysis of an ester

Soap Formation from Triglycerides

Triglycerides are lipids made of a glycerol backbone linked to three fatty acids. They are common in vegetable oils and animal fats. Plant lipids are the basis of vegetable oils, while animal lipids are used as lard or general sources of fats. A fatty acid has a long carbon chain, usually between 12 and 20 carbons, with a weak organic acid at one end. Some fatty acids contain double bonds. These are unsaturated fats. The double bond usually gives the chain a bent, cis shape. As a result,...

synthesis of luminol

Luminol Chemiluminescence in Forensics

Luminol chemiluminescence shows how a chemical reaction can produce light and help with blood detection. Chemical reactions may be endothermic or exothermic, depending on whether they absorb or release heat as reactants become products. The enthalpy of a reaction is the energy difference between reactants and products, or ΔH. A positive ΔH means the reaction is endothermic. A negative ΔH means it is exothermic. Many reactions do not happen in a single step. They can pass through intermediates...

esterification

Ester Formation and Everyday Fragrances

Esters are organic compounds with a carbonyl group attached to an oxygen that connects to another alkyl or aryl group. Their general formula is RCOOR'. They are often made by reacting a carboxylic acid with an alcohol in an esterification reaction. In this process, the hydroxyl group of the acid is replaced by an alkyl or aryl group. Many simple esters have familiar fruit and flower smells because their structures are small and less complex. Formic acid and methanol can combine to form methyl...

identification of unknown aldehydes and ketones

identification-of-unknown-aldehydes-and-ketones

Carbonyl Tests for Aldehydes and Ketones

Aldehydes and ketones are carbonyl compounds, which means they contain a C=O functional group. A ketone has two alkyl or aryl groups attached to the carbonyl carbon. Acetone is the simplest ketone, with two methyl groups. An aldehyde is similar, but it has at least one hydrogen attached to the carbonyl carbon. Formaldehyde is the simplest aldehyde, and acetaldehyde has one hydrogen and one methyl group. The carbonyl carbon in both aldehydes and ketones is electrophilic because the oxygen atom...

uv-vis spectroscopy of dyes

How Dyes Absorb Visible Light

Dyes absorb visible light because their molecular structure lets them interact with specific wavelengths. When light hits a substance, some light is absorbed and the rest is reflected or transmitted. The color we see depends on the wavelength that is reflected. A blue substance reflects blue light, around 430 to 480 nm, and absorbs the complementary orange region, around 590 to 630 nm. Compounds that do not absorb in the visible range appear colorless to the human eye. Light also has energy and...

identifying alcohols

Alcohol Tests for Primary, Secondary, and Tertiary

Alcohol tests can help sort alcohols by structure and reactivity. Alcohols are organic molecules with a hydroxyl group attached to an alkyl or aryl group, written as ROH. If the carbon with the hydroxyl group has one R group, the alcohol is primary. If it has two R groups, it is secondary. If it has three R groups, it is tertiary. Alcohols can also be aromatic when they contain a benzene ring. Phenol is the simplest aromatic alcohol. To identify an alcohol, chemists can use its chemical...

chemistry

Comprehensive, curriculum-focused videos for both instructors and students in introductory chemistry lab courses.

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Explore how hydrogen electrons jump between energy levels and produce discrete emission lines, including the visible Balmer series and other hydrogen spectra.

Hydrogen Emission Lines | JoVE K12

Louisiana Student Standards for Science

motion-and-stability-forces-and-interactions

Motion And Stability: Forces And Interactions

HS-PS2-6

Tennessee Academic Standards

waves-and-their-applications-in-technologies-for-information-transfer

Waves and Their Applications in Technologies for Information Transfer

CHEM1.PS4.1

Next Generation Science Standards

Earth and Space Science

Earth’s Place in the Universe

HS-ESS1-2

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

Matter and Its Interactions

C-PS1-4

Georgia Standards of Excellence

9-12

SC1.

Light Emission and Electron Movement

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Chemistry의 발머 시리즈 강사용 준비 - 220+ 조회수 | JoVE Lab Manual

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Chemistry의 발머 시리즈 학생 프로토콜 - 503+ 조회수 | JoVE Lab Manual

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

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 ...

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 ...

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

IPC.7.B

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

Hydrogen Emission Lines

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