Name: from atomos to the modern atom
Uploaded: 2023-06-23T15:38:43.000Z
Duration: 1 min 17 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Space Systems

3.3.9-12.C

Atomic Structure

Каждый элемент состоит из мельчайших частиц, называемых атомами. Эти частицы придают каждому элементу различные физические и химические свойства, такие как температура кипения, температура плавления и плотность.
Все атомы элемента имеют идентичные свойства, но отличаются от других элементов.
Такие различия обусловлены субатомными частицами — протонами, нейтронами и электронами.
И протоны, и нейтроны вносят свой вклад в атомную массу, по одной единице атомной массы каждый, в то время как электроны имеют почти ничтожную массу.
Протоны и нейтроны сгруппированы в центральном ядре. Количество протонов, равное атомному номеру, определяет конкретный элемент.
Протоны заряжены положительно, а нейтроны не заряжены, поэтому ядро имеет суммарный положительный заряд.
Облако отрицательно заряженных электронов притягивается к ядру. Это облако в основном пустое и составляет большую часть объема атома.
Нейтральный атом содержит равное количество протонов и электронов, что нивелирует положительные и отрицательные заряды и приводит к отсутствию суммарного заряда.

Строение атома

Греческий философ Демокрит выдвинул гипотезу, что все на Земле состоит из крошечных частиц, называемых "атомос", что в переводе с греческого означает "неделимый", отсюда и происходит современный термин "атом". В 19 веке Джон Дальтон сформулировал основные положения атомной теории, актуальные и по сей день. Он предложил пять постулатов для объяснения того, как атомы составляют мир вокруг нас. (1) Вся материя состоит из бесконечно маленьких частиц или атомов. (2) Все атомы данного элемента идентичны друг другу и (3) отличаются от атомов других элементов. (4) Два или более элемента могут сочетаться в фиксированном соотношении, образуя соединение. (5) Атомы не могут быть созданы или уничтожены в химической реакции, но могут перестраиваться, образуя новые вещества.

Далтон был лишь частично прав о частицах, составляющих вещество. В то время как атомы не могут быть разложены дальше обычных химических или физических процессов, они состоят из трёх меньших субатомных частиц. Первый намёк о субатомной структуре появился, когда Джей Джей Томсон открыл электрон. Учёные знали, что общий заряд атома нейтрален, но "пудинговая модель" атома Томсона предоставила новую информацию о существовании отрицательно заряженной частицы, предполагая, что электроны расположены повсюду в положительно заряженной области. Позже Эрнест Резерфорд провёл эксперимент, показывающий, что большая часть массы атома сосредоточена в ядре, где протоны обеспечивают положительный заряд атома, и крошечные отрицательно заряженные электроны занимают большую часть пространства вне ядра. Это опровергло пудинговую модель Томсона. В 1932 году Джеймс Чэдвик открыл, что нейтрон отвечает за массу, присутствующую в атоме.

Согласно принятой на сегодняшний день теории, протоны находятся в ядре атома, имеют положительный заряд и имеют массу одной атомной единицы массы. Количество протонов соответствует атомному номеру в периодической таблице и определяет идентичность элемента. Нейтроны также находятся в ядре. Они не имеют заряда, но имеют такую же массу, как у протонов, что влияет на атомную массу. Электроны вращаются вокруг ядра в облаках. У них отрицательный заряд и незначительная масса, поэтому они влияют на общий заряд атома, но не на его массу.

Греческий философ Демокрит предположил, что все на Земле состоит из мельчайших частиц, называемых атомосами, что в переводе с греческого означает «неделимые», из которых...

Education

JoVE Core

Anatomy and Physiology

Анатомия и физиология

Unit 1

Раздел 1

Fundamentals of Chemistry

Основы химии

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

from atomos to the modern atom

Atoms are the tiny building blocks of matter, and ideas about them go back to the Greek philosopher Democritus. He suggested that everything on Earth is made of atomos, a Greek word meaning &quot;indivisible.&quot; That idea later led to the modern word atom.

In the 19th century, John Dalton developed an atomic theory that is still largely correct today. He proposed five key ideas. All matter is made of tiny particles called atoms. Atoms of the same element are alike, and atoms of different elements are not. He also said that elements combine in fixed ratios to form compounds, and that atoms are not created or destroyed in a chemical reaction. Instead, they rearrange to make new substances.

Dalton’s model was only partly complete. Atoms cannot be broken down by ordinary chemical or physical processes, but they do contain smaller subatomic particles. The first major clue came from J. J. Thomson, who discovered the electron. At the time, scientists knew atoms were neutral overall, so Thomson’s plum pudding model suggested that negative electrons were spread through a positively charged material.

Later, Ernest Rutherford carried out an experiment that changed the atomic model. His results showed that most of an atom’s mass is packed into a central nucleus. In this model, protons provide the atom’s positive charge, and the tiny negative electrons take up most of the space outside the nucleus. This finding disproved Thomson’s plum pudding model.

In 1932, James Chadwick discovered the neutron, which explained the mass still present in the atom. In the accepted model today, protons and neutrons are in the nucleus. Protons have a positive charge and a mass of one atomic mass unit, or AMU, each. The number of protons equals the atomic number on the periodic table and defines the element. Neutrons have no charge, but they have about the same mass as protons, so they add to atomic mass. Electrons move in clouds around the nucleus. They have a negative charge and very little mass, so they affect the atom’s overall charge more than its mass.

From Atomos to the Modern Atom

what is matter?

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the periodic table and organismal elements

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atomic structure

Atoms are the tiny building blocks of matter, and ideas about them go back to the Greek philosopher Democritus. He suggested that everything on Earth is made of atomos, a Greek word meaning "indivisible." That idea later led to the modern word atom. In the 19th century, John Dalton developed an atomic theory that is still largely correct today. He proposed five key ideas. All matter is made of tiny particles called atoms. Atoms of the same element are alike, and atoms of different elements are...

chemical symbols

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atomic weight

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electron behavior

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hydrogen bonds

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Atomic Charges, Bonds, and Compounds

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factors influencing the rate of chemical reactions

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Chemical Reaction Rates and Catalysts

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acids, bases and neutralization reactions

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key terms and concepts

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From Atomos to the Modern Atom | JoVE K12

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Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-1

Next Generation Science Standards

Earth’s Place in the Universe

HS-ESS1-3

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

South Carolina College and Career Ready Science Standards

Matter and Its Interactions

C-PS1-1

C-PS1-2

C-PS1-3.

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

C-PS2-6.

Georgia Standards of Excellence

Physical Science

SPS1.

Atomic Structure of atoms

the-principle-of-superposition-and-the-gravitational-field

The Principle of Superposition and the Gravitational Field

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Circular Orbits and Critical Velocity for Satellites

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Kepler's Second Law of Planetary Motion

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Kepler's Third Law of Planetary Motion

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Nuclear Fission

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Radioactivity and Nuclear Equations

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Nuclear Stability

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Students who demonstrate understanding can develop a model based on evidence to illustrate the life span of the sun and the role of nuclear fusion in the sun's core to release energy in the form of radiation.  Clarification Statement: Emphasis is on the energy transfer mechanisms that allow energy from nuclear fusion in the sun's core to reach Earth.  Examples of evidence for the model include observations of the masses and lifetimes of other stars, as well as the ways that the sun's radiation varies due to sudden solar flares ("space weather"), the 11-year sunspot cycle, and non-cyclic variations over centuries.  Assessment Boundary: Assessment does not include details of the atomic and sub-atomic processes involved with the sun's nuclear fusion.

3.3.9-12.A

Emission Spectra

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Detection of Black Holes

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Metal Flame Emission

Metal Flame Emission
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Molecular Spectroscopy: Absorption and Emission

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Atomic Absorption Spectroscopy: Radiation and Light Sources

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Students who demonstrate understanding can construct an explanation of the Big Bang theory based on astronomical evidence of light spectra, motion of distant galaxies, and composition of matter in the universe.  Clarification Statement: Emphasis is on the astronomical evidence of the red shift of light from galaxies as an indication that the universe is currently expanding, the cosmic microwave background as the remnant radiation from the Big Bang, and the observed composition of ordinary matter of the universe, primarily found in stars and interstellar gases (from the spectra of electromagnetic radiation from stars), which matches that predicted by the Big Bang theory (3/4 hydrogen and 1/4 helium).  Assessment Boundary:

3.3.9-12.B

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The Greek philosopher Democritus proposed that everything on Earth is made up of tiny particles called atomos, Greek for &#34;indivisible,&#34; from which ...

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3.3.9-12.D

From Atomos to the Modern Atom

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