ATOMIC THEORY
Atomic Theory
Atomos
by Democritus
His model stated that matter consists of indivisible particles called atoms and that were empty space. He stated that atoms are indestructible, unchangeable and empty spaced. The atomic model was solid, and stated all atoms differ in size shape, mass position and arrangement, with a void exists between them. He called it atomos meaning indivisible.Main contribution:
His contribution wasn’t similar to the modern atomic models, but his contributions made possible for further scientist to investigate more and keep contributing to the atomic models.
Wrong: It is wrong since he stated that the atom was the smallest particle, which we now know it’s not true since, there are subatomic particles which are the electron, neutron and proton. We also know that the atom is not empty spaced, but the electrons move in waves around the nucleus.
(460-370 B.C.E.)
Atomic model
by Dalton
Dalton atomic model also known as billiard ball, is a model representing what was thought to be an atom. Dalton claimed that atoms of different elements vary in size and mass, this claim is the cardinal feature of his atomic theory, one of its main contributions was also the claim that atoms are invisible, those of a given element are identical, and compounds are combinations of different type of atoms.
(1766 - 1844 C.E.)
ATOMIC THEORY
ATOMIC THEORY
Plum Pudding model
by J.J Thomson
Thomson knew that atoms had a general neutral charge. Therefore, he reasoned that there must be a source of positive charge within the atom to counteract the negative charge of the electrons. This led Thomson to propose that atoms could be described as negative particles floating within a soup of diffuse positive charge. J.J. Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons.
(1856 – 1940 C.E.)
Gold foil model
by Rutherford
The model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun.The main problem with Rutherford’s model was that he couldn't explain why negatively charged electrons remain in orbit when they should instantly fall into the positively charged nucleus. This problem would be solved by Niels Bohr in 1913.
(1871 – 1937 C.E.)
ATOMIC THEORY
ATOMIC THEORY
PLANETARY MODEL
by Bohr
In the Bohr model of the atom, electrons travel in defined circular orbits around the nucleus. The orbits are labeled by an integer, the quantum number n. Electrons can jump from one orbit to another by emitting or absorbing energy.
Bohr’s model is significant because the laws of classical mechanics apply to the motion of the electron about the nucleus only when restricted by a quantum rule. Although Rule 3 is not completely well defined for small orbits, Bohr could determine the energy spacing between levels using Rule 3 and come to an exactly correct quantum rule.
The main problem with Bohr's model is that it works very well for atoms with only one electron, like H or He+, but not at all for multi-electron atoms. Bohr's model breaks down when applied to multi-electron atoms. It does not account for sublevels (s,p,d,f), orbitals or electron spin.
(1885 - 1962 C.E.)
Quantum Mechanics Model
by Schrödinger
Erwin Schrödinger proposed the quantum mechanical model of the atom, which treats electrons as matter waves. Electrons have an intrinsic property called spin, and an electron can have one of two possible spin values: spin-up or spin-down. Any two electrons occupying the same orbital must have opposite spins. Main contribution: Erwin Schrödinger showed that the quantization of the hydrogen atom's energy levels that appeared in Niels Bohr's atomic model could be calculated from the Schrödinger equation, which describes how the wave function of a quantum mechanical system (in this case, a hydrogen atom's electron) evolves. Wrong: To this day, this is the most accepted model, so it don’t have any particular error.
(1887 - 1961 C.E.)
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Transcript
ATOMIC THEORY
Atomic Theory
Atomos
by Democritus
His model stated that matter consists of indivisible particles called atoms and that were empty space. He stated that atoms are indestructible, unchangeable and empty spaced. The atomic model was solid, and stated all atoms differ in size shape, mass position and arrangement, with a void exists between them. He called it atomos meaning indivisible.Main contribution: His contribution wasn’t similar to the modern atomic models, but his contributions made possible for further scientist to investigate more and keep contributing to the atomic models. Wrong: It is wrong since he stated that the atom was the smallest particle, which we now know it’s not true since, there are subatomic particles which are the electron, neutron and proton. We also know that the atom is not empty spaced, but the electrons move in waves around the nucleus.
(460-370 B.C.E.)
Atomic model
by Dalton
Dalton atomic model also known as billiard ball, is a model representing what was thought to be an atom. Dalton claimed that atoms of different elements vary in size and mass, this claim is the cardinal feature of his atomic theory, one of its main contributions was also the claim that atoms are invisible, those of a given element are identical, and compounds are combinations of different type of atoms.
(1766 - 1844 C.E.)
ATOMIC THEORY
ATOMIC THEORY
Plum Pudding model
by J.J Thomson
Thomson knew that atoms had a general neutral charge. Therefore, he reasoned that there must be a source of positive charge within the atom to counteract the negative charge of the electrons. This led Thomson to propose that atoms could be described as negative particles floating within a soup of diffuse positive charge. J.J. Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons.
(1856 – 1940 C.E.)
Gold foil model
by Rutherford
The model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun.The main problem with Rutherford’s model was that he couldn't explain why negatively charged electrons remain in orbit when they should instantly fall into the positively charged nucleus. This problem would be solved by Niels Bohr in 1913.
(1871 – 1937 C.E.)
ATOMIC THEORY
ATOMIC THEORY
PLANETARY MODEL
by Bohr
In the Bohr model of the atom, electrons travel in defined circular orbits around the nucleus. The orbits are labeled by an integer, the quantum number n. Electrons can jump from one orbit to another by emitting or absorbing energy. Bohr’s model is significant because the laws of classical mechanics apply to the motion of the electron about the nucleus only when restricted by a quantum rule. Although Rule 3 is not completely well defined for small orbits, Bohr could determine the energy spacing between levels using Rule 3 and come to an exactly correct quantum rule. The main problem with Bohr's model is that it works very well for atoms with only one electron, like H or He+, but not at all for multi-electron atoms. Bohr's model breaks down when applied to multi-electron atoms. It does not account for sublevels (s,p,d,f), orbitals or electron spin.
(1885 - 1962 C.E.)
Quantum Mechanics Model
by Schrödinger
Erwin Schrödinger proposed the quantum mechanical model of the atom, which treats electrons as matter waves. Electrons have an intrinsic property called spin, and an electron can have one of two possible spin values: spin-up or spin-down. Any two electrons occupying the same orbital must have opposite spins. Main contribution: Erwin Schrödinger showed that the quantization of the hydrogen atom's energy levels that appeared in Niels Bohr's atomic model could be calculated from the Schrödinger equation, which describes how the wave function of a quantum mechanical system (in this case, a hydrogen atom's electron) evolves. Wrong: To this day, this is the most accepted model, so it don’t have any particular error.
(1887 - 1961 C.E.)