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The Development of the Atomic Model

 
2.2  The Development of Atomic Model
 
Subatomic Particles
  • An atom is made up of smaller subatomic particles which are proton, electron and neutron. 
  • Proton and neutrons are located at the nucleus of the atom. 
  • Electrons move around the nucleus at a high speed. 
  • The mass of the atom is concentrated at the centre of the atom. 

This image illustrates the structure of an atom. At the center, there is a nucleus containing protons and neutrons. The protons are labeled and depicted as red spheres, while the neutrons are labeled and shown as green spheres. Surrounding the nucleus is a larger blue area representing the electron cloud, with electrons labeled and illustrated as smaller red spheres orbiting the nucleus. The background appears to be a lined notebook page.
 
Comparison between the Subatomic Particles
Proton Electron Neutron
Relative Charge
+1 -1 0
Position
Nucleus Moves around the nucleus Nucleus
Relative Mass
1 \(\dfrac{1}{1840}\) 1
 
The diagram shows THE HISTORICAL DEVELOPMENT OF THE ATOMIC STRUCTURE MODEL, J.J. Thomson (1856-1940), Niels Bohr (1885-1962), John Dalton (1766-1844), Ernest Rutherford (1871-1937). James Chadwick (1891-1974) Pandai
 
Model of Atom Explaination
John Dalton
The image shows a large, bright cyan circle centered on a white background with light blue horizontal lines. There is also a thin vertical red line on the left side of the image. The lines resemble those found on a sheet of lined paper.
  • All matter is composed of extremely small particles called atoms.
  • All atoms are the same for one kind of element.
  • Atom can not be created or divided into smaller particles.
  • In a chemical reaction, atoms are separated, combined, or rearranged.
J.J Thomson
This image shows a diagram of an atom based on the ‘plum pudding’ model. It features a large blue circle labeled ‘Spherical cloud of positive charge’ with several small red circles inside it, each marked with a minus sign (-) to represent electrons. There are also plus signs (+) scattered within the blue circle to indicate the positive charge. The red circles are labeled ‘Electron.’The background appears to be lined paper..
  • An atom consists of small negatively charged particles called electrons. 
  • The atom is a positively charged spherical cloud with electrons positioned uniformly throughout the atom. 
Ernest Rutherford
This is an illustration of an atom. The nucleus, which consists of protons, is at the center and is labeled. Surrounding the nucleus are electrons, depicted as red circles with a negative sign, orbiting the nucleus. The background is lined paper.
  • Proton, which is a positively charged particle, is discovered. 
  • Proton and most of the mass of the atom is located at the nucleus, which is the centre of the atom. 
  • The atom is mostly empty space. 
Neils Bohr
This is a diagram of an atom. The nucleus, which consists of protons, is at the center and is marked with a plus sign. Electrons are shown orbiting the nucleus in various shells. The diagram labels the nucleus, electrons, and shells.
  • Electrons move around the nucleus in their fixed shells.
  • The shells formed are circles with a fixed radius from the nucleus. 
  • Electrons at each shell have their own fixed energy level. 
James Chadwick
This image illustrates an atomic structure. It shows a nucleus at the center, consisting of protons and neutrons. Surrounding the nucleus are electrons depicted in orbitals or shells. The nucleus is labeled, and the electrons and shells are also labeled for clarity.
  • Discovered the presence of the neutrons in the nucleus through an experiment where the beryllium-9 atom is bombarded with alpha particles. 
  • Proposed that half of the mass of an atom is contributed by the neutron. 
 

 

 

 

 

 

 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of pandai.

The Development of the Atomic Model

 
2.2  The Development of Atomic Model
 
Subatomic Particles
  • An atom is made up of smaller subatomic particles which are proton, electron and neutron. 
  • Proton and neutrons are located at the nucleus of the atom. 
  • Electrons move around the nucleus at a high speed. 
  • The mass of the atom is concentrated at the centre of the atom. 

This image illustrates the structure of an atom. At the center, there is a nucleus containing protons and neutrons. The protons are labeled and depicted as red spheres, while the neutrons are labeled and shown as green spheres. Surrounding the nucleus is a larger blue area representing the electron cloud, with electrons labeled and illustrated as smaller red spheres orbiting the nucleus. The background appears to be a lined notebook page.
 
Comparison between the Subatomic Particles
Proton Electron Neutron
Relative Charge
+1 -1 0
Position
Nucleus Moves around the nucleus Nucleus
Relative Mass
1 \(\dfrac{1}{1840}\) 1
 
The diagram shows THE HISTORICAL DEVELOPMENT OF THE ATOMIC STRUCTURE MODEL, J.J. Thomson (1856-1940), Niels Bohr (1885-1962), John Dalton (1766-1844), Ernest Rutherford (1871-1937). James Chadwick (1891-1974) Pandai
 
Model of Atom Explaination
John Dalton
The image shows a large, bright cyan circle centered on a white background with light blue horizontal lines. There is also a thin vertical red line on the left side of the image. The lines resemble those found on a sheet of lined paper.
  • All matter is composed of extremely small particles called atoms.
  • All atoms are the same for one kind of element.
  • Atom can not be created or divided into smaller particles.
  • In a chemical reaction, atoms are separated, combined, or rearranged.
J.J Thomson
This image shows a diagram of an atom based on the ‘plum pudding’ model. It features a large blue circle labeled ‘Spherical cloud of positive charge’ with several small red circles inside it, each marked with a minus sign (-) to represent electrons. There are also plus signs (+) scattered within the blue circle to indicate the positive charge. The red circles are labeled ‘Electron.’The background appears to be lined paper..
  • An atom consists of small negatively charged particles called electrons. 
  • The atom is a positively charged spherical cloud with electrons positioned uniformly throughout the atom. 
Ernest Rutherford
This is an illustration of an atom. The nucleus, which consists of protons, is at the center and is labeled. Surrounding the nucleus are electrons, depicted as red circles with a negative sign, orbiting the nucleus. The background is lined paper.
  • Proton, which is a positively charged particle, is discovered. 
  • Proton and most of the mass of the atom is located at the nucleus, which is the centre of the atom. 
  • The atom is mostly empty space. 
Neils Bohr
This is a diagram of an atom. The nucleus, which consists of protons, is at the center and is marked with a plus sign. Electrons are shown orbiting the nucleus in various shells. The diagram labels the nucleus, electrons, and shells.
  • Electrons move around the nucleus in their fixed shells.
  • The shells formed are circles with a fixed radius from the nucleus. 
  • Electrons at each shell have their own fixed energy level. 
James Chadwick
This image illustrates an atomic structure. It shows a nucleus at the center, consisting of protons and neutrons. Surrounding the nucleus are electrons depicted in orbitals or shells. The nucleus is labeled, and the electrons and shells are also labeled for clarity.
  • Discovered the presence of the neutrons in the nucleus through an experiment where the beryllium-9 atom is bombarded with alpha particles. 
  • Proposed that half of the mass of an atom is contributed by the neutron. 
 

 

 

 

 

 

 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of pandai.
Chapter : Matter and Atomic Structure
Topic : The Development of the Atomic Model
Form 4 Chemistry
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