Modelos atómicos (Dalton, Thomson, Rutherford, Bohr y Chadwick)
Summary
TLDRThis video script provides a historical overview of atomic theory, starting with Democritus' concept of indivisible 'atoms' and progressing through significant scientific discoveries. In 1808, John Dalton defined atoms as the smallest units of elements, identical in size, mass, and chemical properties. Dalton's atomic theory laid the groundwork for understanding that different elements have distinct properties due to variations in their atomic structure. The script then moves to Joseph Thomson's discovery of the electron in 1897, leading to the 'plum pudding' model of the atom, where electrons are scattered throughout a sphere of positive charge. However, Ernest Rutherford's gold foil experiment in 1909 revealed a small, positively charged nucleus with electrons orbiting around it, which led to the planetary model of the atom. Niels Bohr further refined the model in 1913 by introducing quantized energy levels for electrons, explaining atomic stability and the emission of photons when electrons transition between these levels. Bohr's work earned him the Nobel Prize in Physics in 1922 and addressed the mystery of atomic weights. The discovery of the neutron by James Chadwick in 1932 completed the picture of the atom, with the neutron being a subatomic particle with no electric charge and slightly more mass than the proton. Chadwick's discovery was honored with the Nobel Prize in Physics in 1935 and explained why helium, with two protons, weighed four times more than hydrogen with one proton. The video concludes by emphasizing how these atomic models and discoveries have contributed to our current understanding of the atom, highlighting the contributions of each scientist and the significance of their findings in shaping modern atomic theory.
Takeaways
- 🤔 Democritus, one of the first philosophers, questioned the nature of matter and proposed the concept of the atom as the smallest indivisible particle.
- 🔬 In 1808, John Dalton defined atoms more precisely as small, indivisible, and indestructible particles that form elements, with all atoms of the same element being identical in size, mass, and chemical properties.
- 🌐 Dalton's atomic theory stated that chemical compounds are formed by the union of atoms of different elements in fixed proportions, with a whole number ratio.
- 🚫 Chemical reactions only involve the separation, combination, or reordering of atoms, without creating or destroying them.
- 🔋 In 1897, J.J. Thomson discovered the electron, a negatively charged particle, leading to a new model of the atom as a sphere of positive electricity with electrons embedded within.
- ⚛️ Ernest Rutherford's gold foil experiment in 1909 revealed that atoms have a mostly empty space with a small, positively charged nucleus, where most of the atom's mass is concentrated.
- ☀️ In 1913, Niels Bohr proposed a planetary model of the atom, suggesting that electrons orbit the nucleus in specific energy levels and can only occupy certain allowed orbits.
- 🏆 Rutherford was awarded the Nobel Prize in Physics in 1908 for his research on the atomic nucleus, and Bohr in 1922 for his contribution to understanding atomic behavior and quantum mechanics.
- 🤔 The problem of atomic weight was unresolved until James Chadwick discovered the neutron in 1932, a subatomic particle with no electric charge and slightly more mass than a proton.
- 🏆 Chadwick's discovery of the neutron earned him the Nobel Prize in Physics in 1935, and it helped explain why heavier elements like helium have more mass than hydrogen, despite having a similar number of protons.
- 🧬 Collectively, these discoveries and models by Dalton, Thomson, Rutherford, Bohr, and Chadwick laid the foundation for our current understanding of the atom.
Q & A
Who is considered one of the first philosophers to question the nature of matter?
-Democritus is considered one of the first philosophers to question the nature of matter, proposing the concept of the atom as an indivisible particle.
What was John Dalton's contribution to the atomic theory?
-John Dalton defined the atom more precisely, proposing that elements are made of small, indivisible, and indestructible particles called atoms, which are identical in size, mass, and chemical properties within the same element.
What was the significance of Joseph Thomson's discovery in atomic theory?
-Joseph Thomson discovered the electron, which led to the understanding that atoms are not indivisible and are composed of smaller particles. He proposed a 'plum pudding' model where electrons are embedded within a sphere of positive charge.
What did Ernest Rutherford's gold foil experiment reveal about the atomic structure?
-Ernest Rutherford's gold foil experiment revealed that atoms have a significant amount of empty space and a small, dense, positively charged nucleus, which led to the proposal of a new atomic model with electrons orbiting around the nucleus.
What was Niels Bohr's contribution to the understanding of atomic structure?
-Niels Bohr developed a planetary model of the atom, suggesting that electrons can only occupy specific energy levels and that an electron can move to a higher energy level by absorbing radiation, and emit energy as a photon when it returns to its original orbit.
Who discovered the neutron and how did this discovery impact the atomic model?
-James Chadwick discovered the neutron, a subatomic particle with no electric charge and slightly more mass than a proton. This discovery helped to explain the mass of atoms, as the neutron contributes significantly to the overall mass, which was previously unaccounted for.
How did the discovery of the electron, proton, and neutron contribute to the modern understanding of the atom?
-The discovery of the electron by Thomson, the proton by Rutherford, and the neutron by Chadwick, along with the development of various atomic models, provided a comprehensive understanding of the atom's structure, with a positively charged nucleus containing protons and neutrons, and electrons orbiting around it.
What is the significance of the atomic number in relation to energy levels?
-The atomic number signifies the number of protons in the nucleus of an atom and also determines the number of electrons in a neutral atom. It is directly related to the energy levels, as each energy level can hold a specific number of electrons, which is crucial for understanding chemical behavior.
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How did the discovery of subatomic particles lead to the development of quantum mechanics?
-The discovery of subatomic particles like electrons, protons, and neutrons, along with the understanding of their behavior in atoms, laid the groundwork for quantum mechanics. This field of physics describes the behavior of matter and energy at the atomic and subatomic level, where classical physics no longer applies.
What is the role of chemical compounds in the context of atomic theory?
-Chemical compounds are formed when two or more atoms of different elements combine in fixed proportions. The understanding of atomic theory explains how these compounds are formed through the sharing or transfer of electrons between atoms, leading to stable molecules with specific properties.
How did the atomic theory evolve from Democritus to the modern understanding of the atom?
-The atomic theory evolved from Democritus's concept of indivisible atoms to Dalton's definition of elements as made of identical atoms, through Thomson's discovery of the electron, Rutherford's discovery of the nucleus, Bohr's planetary model with quantized energy levels, and finally, Chadwick's discovery of the neutron, leading to the modern understanding of the atom as a complex system of subatomic particles.
What are the implications of atomic theory for the field of chemistry?
-Atomic theory is fundamental to chemistry as it explains the nature of elements, their reactivity, and the formation of chemical bonds. Understanding the structure and properties of atoms allows chemists to predict how different substances will interact, form compounds, and participate in chemical reactions.
Outlines
🧬 The Atomic Theory Evolution
The first paragraph introduces the concept of atoms and their historical significance. Democritus, an early philosopher, proposed that matter could be divided into indivisible particles called atoms. This idea was later refined by John Dalton in 1808, who defined atoms as the smallest units of matter that form elements. Dalton's atomic theory stated that all atoms of an element are identical in size, mass, and chemical properties. The paragraph also mentions that chemical compounds are formed by the union of atoms from different elements in fixed proportions. Dalton's theory was later challenged by discoveries that atoms have smaller particles within them. Joseph Thomson's experiments with cathode rays led to the discovery of the electron, a negatively charged particle. Thomson proposed a 'plum pudding' model of the atom, where electrons are scattered within a sphere of positive charge. Ernest Rutherford's gold foil experiment provided evidence for a small, positively charged nucleus at the center of the atom, with electrons orbiting around it. Rutherford's model suggested that nearly all the mass of an atom is concentrated in the nucleus, and he was awarded the Nobel Prize in Physics in 1908 for his work on atomic structure.
🌟 Quantum Mechanics and Atomic Structure
The second paragraph discusses the development of quantum mechanics and its impact on the understanding of atomic structure. Niels Bohr, in 1913, developed a planetary model of the atom, proposing that electrons orbit the nucleus in specific energy levels. Electrons could only occupy these quantized orbits and could move to higher energy levels by absorbing radiation. When an electron returns to its original orbit, it emits the absorbed energy as a photon. Bohr also assigned a number to each energy level, determining the maximum number of electrons that could occupy it. His work earned him the Nobel Prize in Physics in 1922 for his contributions to understanding atomic behavior and quantum mechanics. However, these models did not fully explain the mass of atoms. James Chadwick's experiments in 1932 led to the discovery of the neutron, a subatomic particle with no electric charge and slightly more mass than a proton. Chadwick's model resolved the mystery of why helium, with two protons, weighed four times more than hydrogen with one proton. The discovery of the neutron explained the additional mass, as the neutron contributes significantly to an atom's weight. Chadwick was awarded the Nobel Prize in Physics in 1935 for discovering the neutron. Collectively, these atomic models and discoveries laid the foundation for our current understanding of the atom.
Mindmap
Keywords
💡Atom
💡Subatomic Particles
💡John Dalton
💡Electron
💡Nucleus
💡Proton
💡Neutron
💡Isotopes
💡Niels Bohr
💡Quantum Mechanics
💡Chemical Compounds
Highlights
Democritus, one of the first philosophers, proposed that matter could be divided down to an indivisible, solid, and indestructible particle called an atom.
In 1808, John Dalton defined atoms as the small, indivisible, and indestructible particles that elements are made of, with all atoms of the same element being identical in size, mass, and chemical properties.
Chemical compounds are formed by the union of two or more atoms from different elements in fixed proportions.
Chemical reactions involve only the separation, combination, or rearrangement of atoms, without creating or destroying them.
In 1890, Joseph Thomson discovered that atoms contained smaller particles when studying cathode rays and proposed the 'plum pudding' model of the atom.
Thomson named the negatively charged particles within the atom 'electrons'.
Ernest Rutherford's gold foil experiment in 1906 led to the discovery that atoms have a mostly empty space with a small, positively charged nucleus.
Rutherford proposed that almost all of an atom's mass is concentrated in the nucleus, which he named 'protons'.
Rutherford's discovery earned him the Nobel Prize in Physics in 1908 for his research on the atomic nucleus structure.
In 1913, Niels Bohr developed a planetary model of the atom with specific energy levels for electrons, which could only occupy certain orbits.
Bohr's model explained why electrons did not collide with the nucleus and was awarded the Nobel Prize in Physics in 1922 for his contributions to quantum mechanics.
James Chadwick's experiments in 1932 led to the discovery of a third type of subatomic particle, the neutron, which has no electric charge and is slightly heavier than a proton.
Chadwick's discovery of the neutron was awarded the Nobel Prize in Physics in 1935.
The discovery of the neutron solved the mystery of why helium, with two protons, weighed four times more than hydrogen with one proton.
The atomic models and discoveries laid the foundation for our current understanding of the atom, including Dalton's atomic definition, Thomson's electron discovery, Rutherford's proton discovery, Bohr's planetary model, and Chadwick's neutron discovery.
Transcripts
[Música]
te has preguntado cómo están hechos los
objetos que ves todos los días esta
pregunta se la hacían desde hace muchos
años uno de los primeros filósofos en
hacerse esa pregunta fue demócrito que
decía que al dividir la materia
llegaríamos a una última particular
sólida e indestructible a esta
particular la llamo átomo que significa
indivisible sin embargo esta definición
sólo sería una pequeña parte de los
descubrimientos que se hicieron tiempo
después
en 1808 el científico inglés john dalton
definió de una forma más precisa las
unidades indivisibles con las que está
hecha la materia
su modelo atómico definía lo siguiente
los elementos están formados por
partículas diminutas
indivisibles e indestructibles llamadas
átomos
todos los átomos del mismo elemento son
idénticos
tienen igual tamaño masa y propiedades
químicas por lo tanto los átomos de
distintos elementos presentan
propiedades diferentes
y los compuestos químicos se forman al
unirse dos o más átomos de diferentes
elementos en proporciones fijas
[Música]
donde la relación de átomos será un
número entero o una pasión sencilla
una reacción química implica sólo la
separación combinación o reordenamiento
de los átomos
nunca supone la creación o destrucción
de los mismos
[Música]
a pesar de las teorías de demócrito y
dalton sobre el átomo como partícula
indivisible una serie de investigaciones
demostraron que el átomo contaba con
partículas más pequeñas
en 1890 el científico joseph thompson
mientras estudiaba en la radiación a
través del magnetismo se dio cuenta que
había una repulsión de los rayos
catódicos como un imán en donde supuso
que debían de haber partículas negativas
y fluía en esa habitación
su modelo atómico proponía lo siguiente
el átomo es una esfera de electricidad
positiva en donde se encuentran los
electrones
[Música]
a las partículas eléctricamente
negativas las llamo electrones
[Música]
aún reconocía al átomo como una
partícula compacta e indivisible thomson
propuso un modelo atómico semejante a
una gelatina con pasas por lo que en
1906 cuando el premio nobel de física
por descubrir el electrónico
después del descubrimiento del electrón
el científico neozelandés ernest
rutherford se propuso a estudiar la
estructura interna del átomo schubert
fort hizo pasar partículas alfa sobre
una lámina de oro observando que algunas
partículas se desviaban con un ángulo
muy grande
descubriendo que el átomo tenía espacios
vacíos
y proponiendo que las cargas positivas
se encontraban concentradas en un
pequeño núcleo
su modelo atómico consistía en que el
átomo estaba formado de un pequeño
núcleo con carga positiva y alrededor de
él se encontraban los electrones
dispersos con diferentes trayectorias
[Música]
también proponía que casi toda la masa
se encontraba en el núcleo
a las cargas positivas las llamo
protones para este entonces
investigaciones anteriores suponían que
si los átomos eran neutros debían de
tener el mismo número de cargas
positivas que los electrones para poder
tener estabilidad
el descubrimiento de rutherford le valió
el premio nobel de física en 1908 por
sus investigaciones sobre la estructura
del núcleo atómico
sabiendo que la carga positiva se
encontraba en el núcleo y la negativa
estaba alrededor de él los científicos
no podían comprender por qué el electrón
no llegaba hasta el núcleo donde está el
protón y colisionaba con él
en 1913 el físico de al mes main sport
desarrolló un modelo atómico abordando
un modelo planetario donde el núcleo es
el sol y los electrones de los planetas
que giran alrededor
él propuso que el electrón solo puede
ocupar ciertas órbitas de energía
específicas
1 electrón puede alcanzar niveles de
energía más altos cuando ésta absorbe
radiación
este exceso de energía excita al átomo
para que pueda pasar de una órbita a
otra por el contrario cuando el electrón
regresa a su órbita original este emite
la energía absorbida en forma de fotón
también asignó un número a cada nivel de
energía el cual solo podía tener un
número determinado de electrones
[Música]
en 1922 recibió el premio nobel de
física por su aportación al
comportamiento del átomo y la mecánica
cuántica
a pesar de la aceptación de los modelos
anteriores éstos generaban un grande
problema sin resolver y este era el peso
de los átomos
[Música]
en 1932 el físico inglés james chadwick
bombardeo una lámina delgada de berilio
con partículas sal para el metal emite
una radiación muy alta similar a los
rayos gamma los siguientes experimentos
demostraron que esos rayos en realidad
eran tercer tipo de partículas
subatómicas sin carga eléctrica
por lo que en 1932 propuso su modelo
atómico el cual determinó que los
neutrones son partículas subatómicas que
no tienen carga eléctrica
y cuya masa es ligeramente mayor a la de
los protones que casi toda la masa se
concentraba en el núcleo a estas
partículas hallamos neutrones ya que son
partículas neutras
este descubrimiento le valió el premio
nobel de física en 1935 por descubrir el
neutrón
con este modelo se resolvía el misterio
del por qué el helio con dos protones
pesaba cuatro veces más que el hidrógeno
con un protón suponiendo que la masa de
los electrones es despreciable ahora se
sabía que el neutrón con masa similar le
daba ese peso extra ya que el libro que
no obtiene neutrón
[Música]
estos modelos atómicos e investigaciones
aleatorias ayudaron a un mejor
entendimiento de cómo está hecha la
materia dalton con su definición de
átomo
thompson con el descubrimiento del
electrón
rutherford con el descubrimiento del
protón
worth con su modelo planetario y niveles
energéticos
y chadwick con el descubrimiento del
neutrón
sentaron las bases de lo que conocemos
hoy como átomo
[Música]
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