Understanding Atoms and Development of Atoms – Basically, every material that exists in this world must have the smallest part, then if that small part is split again, then there will be even smaller parts. Well, that small part of the smallest part is called an atom.
The atom itself can be said to be the smallest constituent of all existing matter. In simple terms, atoms can be interpreted like that. In addition, in the world of science, atoms have their development. Every development in the atom is the result of an evaluation of the previous atomic theory.
Want to know a more complete explanation about the meaning of atoms and want to know the development of atoms? What are you waiting for, read this article right away, then you will know the meaning and development of the atom.
An understanding must begin with the word. As with atoms, the word atom itself comes from the Greek, atomos . Atomos means indivisible. Meanwhile, the meaning of atoms according to experts also varies. The following is the meaning of the atom according to experts.
1. Leucippus and Democritus
Atom is the smallest part of a material that can not be divided into certain parts. Atoms are the building blocks of all matter in this world.
Atoms are the smallest particles of a substance that cannot be broken down into smaller particles by ordinary chemical reactions.
3.Joseph John Thompson
The atom is a ball that is positively charged and surrounded by electrons like a raisin.
4. Ernest Rutherford
Atoms are particles consisting of protons and neutrons surrounded by electrons.
Meanwhile, in the Big Indonesian Dictionary (KBBI) atom means the smallest chemical element (after nuclear) that can stand alone and can be combined with others. Not only that, from the four definitions of atom that have been disclosed, the atom can be interpreted as the smallest particle and cannot be divided.
“The smallest and indivisible particle”, this thought comes from Democritus. He was the first scientist to reveal it. This thought or opinion about the atom is not a scientific research, but only Democritus’s thoughts.
From the thoughts of Democritus, many scientists are challenged to research research on atoms. In fact, until now, atomic research is still ongoing.
In general, atoms are shaped like a circle with a diameter of 6-30 mm. The electromagnetic force that exists in atoms can bind particles, such as protons, neutrons, and electrons.
The binding of atoms with protons, neutrons and electrons makes these atoms and particles form a molecule. Until now, atoms cannot be seen by various kinds of technological tools.
The atomic nucleus is commonly called the nucleus. Atoms have a nucleus surrounded by electrons, protons and neutrons. Electrons have a negative charge. While the proton has a positive. After there is a positive and negative charge, then the neutron can be said to have a charge that does not side with anyone, simply, the neutron is neutral.
Along with the development of science, especially in physics, there are already many scientists who research and analyze atomic theory. These scientists were John Dalton, JJ Thompson, Ernest Rutherford, and the last scientist to research the atom was Niels Bohr.
1. Dalton’s Atomic Theory
John Dalton was the first scientist to develop atomic theory in 1803. The theory developed was the result of John Dalton’s experiments in developing Democritus’ atomic thinking. John Dalton also thought that the atom was shaped like a billiard ball.
John Dalton thought that the atom is the smallest particle that can not be divided again. In other words, elements combined with atoms have a fixed composition.
Broadly speaking, John Dalton’s atomic theory, as follows:
a) Atom is the smallest part of a material that can not be divided.
b) The particles that make up the atom have the same substance.
c) Atoms of certain elements cannot change into atoms of other elements.
d) Two or more atoms can combine or react to form a molecule.
e) In a chemical reaction, the ratio between the constituent atoms has a certain and simple ratio.
Although John Dalton can be said to be the first scientist to develop the atomic theory, this theory still has some drawbacks, including:
a) Along with the development of atomic theory, it turns out that atoms can be converted into atoms of other elements by nuclear reactions. In this case, proving that John Dalton’s assumption that atoms cannot be created or destroyed is wrong.
b) With the existence of isotopes, John Dalton’s assumption that the atoms of an element are similar in many ways is incorrect. Isotopes prove that the same atom will have the same atomic number, but different mass numbers.
c) Along with the development of atomic theory, many compounds with non-integer and non-simple ratios have been found. With this, it can be said that John Dalton’s theory which revealed that the ratio of elements in a compound has a unanimous ratio can be broken.
In 1886, a positively charged electric particle, known as the proton, was discovered. The inventor of this electric particle is a scientist named Eugene Goldstein.
Then in 1897, Thomson discovered a particle that has a negative charge which is currently called the electron. Then in 1932, the discovery of particles with a neutral charge was James Chadwick who discovered these particles.
Particles of protons, electrons and neutrons that have been found can break John Dalton’s atomic theory which states that atoms can no longer be divided. This can be said to be one of the shortcomings of John Dalton’s atomic theory.
As already discussed, John Dalton’s atomic theory has quite a number of flaws. Even though there were quite a number of shortcomings from his atomic theory, John Dalton is still considered the father of the originator of modern atomic theory.
2. Thomson’s Atomic Theory
In Thomson’s atomic theory, atoms are described as raisin buns. Why is the atom like raisin bread? Because Thomson assumed that atoms that have a positive charge are surrounded by negatively charged electrons.
The discovery of negatively charged subatomic particles by Thomson could break John Dalton’s atomic theory, especially about atoms that do not have subatoms. In other words, Thomson’s atomic theory proved that atoms still have sub-particles or sub-atoms.
In developing his theory, Thomson stated that the atom as a whole is neutral. This is because electrons with a negative charge need other positively charged particles that function to neutralize the negative charge on the atom.
Broadly speaking, the atomic theory expressed by Joseph John Thomson can be summed up in a number of ways, namely:
a) Atoms are not the smallest part of a particle.
b) As a whole, the atom is neutral.
c) The mass of the electron is less than the mass of the atom.
d) Positively charged atoms will spread throughout the atom, then neutralized by electrons.
e) A neutrally charged atom has the same positive charge and negative charge. In other words, there is no excess positive charge or negative charge on an atom.
The unfortunate thing about Thomson’s theory is that no one has developed this theory. In fact, Thomson’s theory had a discrepancy with Ernest Rutherford’s atomic theory. Ernest Rutherford’s atomic theory proved that the positive charge in an atom is not evenly distributed.
In other words, the positive charge on the atom is only concentrated in the middle of the atom, so it is called the atomic nucleus.
One of the other weaknesses, Thomson’s atomic theory cannot explain the positive charge and negative charge on the atom. In addition, Joseph John Thomson did not know that in the atom itself there is something called the atomic nucleus.
The most valuable and very useful thing from Thomson’s atomic theory is that Thomson succeeded in proving that there are other negatively charged particles in atoms. In addition, with Thomson’s theory, we know that the atom is neutral or the number of positive charges and negative charges is balanced.
3. Rutherford’s Atomic Theory
More precisely in 1910, Rutherford and together with two of his assistants managed to find the atomic nucleus which has a smaller radius than the atom. Rutherford’s theory stems from experiments bombarding the nuclei of gold plates with alpha particles (a particle with four times the mass of a hydrogen atom and twice the positive charge.
The atomic bombardment experiment is known as the Geiger-Marsdeng. The name on the experiment can be said to be a form of appreciation from Rutherford to his two assistants. Both of them or Rutherford’s assistants have their full names, Hans Geiger and Ernest Masrreden.
At that time, Rutherford made a design or sketch with two of his assistants to bombard gold atoms with alpha particles emitted by radioactive elements. From this experiment, radioactive rays can be deflected, forwarded, and reflected. However, from the results of the experiments that have been carried out, there is a fact that there are alpha particles that are deflected at an angle between 900 and 1800.
Based on the research or experiments carried out, it can be concluded that if an alpha particle hits an atomic nucleus, then a collision can occur which will result in deflection or reflection of the alpha particle. The occurrence of this can be caused by the mass and charge of the atom concentrated in the atomic nucleus (nucleus).
With this, Rutherford assumed that the charge of the atomic nucleus is proportional to the atomic mass in amu (atomic mass unit). In addition, the results from Rutherford’s experiment also broke Thomson’s idea which stated that atoms are like raisin bread with electrons spread evenly throughout the atom.
Broadly speaking, Rutherford’s atomic theory can be divided into several points, namely:
a) Atoms are composed of an atomic nucleus (nucleus) and electrons that revolve around it.
b) The positive charge or atomic mass is concentrated in the atomic nucleus.
c) Atoms are neutral. This is because the total charge on the atomic nucleus is equal to the total charge on the electrons.
d) The scattering of alpha particles is not affected by the electron cloud.
e) Most of the volume of an atom is empty space (not solid) because the radius of the atomic nucleus is much smaller than the atomic radius.
Although Rutherford’s atomic theory was an improvement over Thomson’s atomic theory, Rutherford’s theory still had some deficiencies. One of the shortcomings of Thomson’s theory is in terms of electron trajectories.
With his theory, Rutherford said that the electron orbits the atomic nucleus on a trajectory that is relatively far from the nucleus. From this statement, the theory is considered contrary to Maxwell’s classical electrodynamic theory.
4. Bohr’s Atomic Theory
At that time, scientists agreed with the results of research conducted by Rutherford. What scientists agreed at that time was that an atom consists of an atomic nucleus and electrons revolving around it.
However, because the electron trajectory applied by Rutherford still had deficiencies, a Danish physicist and 1922 Nobel Prize winner in Physics named Niels Bohr improved Rutherford’s atomic theory.
He carried out a series of experiments or research just to perfect Rutherford’s atomic theory. Niels Bohr used Planck’s nuclear atomic model and quantum theory to refine Rutherford’s atomic theory. Until now this atomic theory is known as the Bohr atomic theory.
In simple terms, Niels Bohr’s model of the atom is almost similar to the rotation of the planets that orbit the solar system. Therefore, this theory is also known as “Niels Bohr’s miniature atomic model of the solar system”.
After conducting research or experiments, finally Niels Bohr found the result that electrons revolve around the atomic nucleus which consists of protons and neutrons in certain trajectories, usually called electron shells or energy levels.
After the electron moves from one shell to another, it will definitely be accompanied by the absorption of a certain amount of energy. If explained simply, there is a migration to the outer skin and a migration to the deeper skin.
Migration to the outer skin, higher energy levels accompanied by energy absorption. Meanwhile, the movement to the skin is deeper, the energy level is lower accompanied by the release of energy.
If taken broadly, Niels Bohr’s atomic theory contains several important points, including:
a) There is a stationary path that has a certain energy. Stationary trajectories are certain trajectories without releasing energy that is rotated by atomic nuclei.
b) No energy in the form of radiation is emitted or absorbed when the electrons are in a stationary trajectory.
c) If the electron absorbs energy from outside, the electron will rise to a higher shell, then return to its original shell by emitting radiant energy.
d) Electrons can move from one path to another. If an electron moves from a path with low energy to a path with high energy. When there is a transfer, electrons will absorb energy and if vice versa electrons will absorb energy.
e) One of the weaknesses of Niels Bohr’s theory is that it cannot explain the spectrum of an atom larger than hydrogen. Not only that, Niels Bohr’s atomic theory also cannot explain the Zeeman effect, namely the atomic spectrum which is more complicated when the atom is placed in a magnetic field.
5. Theory of Quantum Mechanics
Weaknesses in Niels Bohr’s atomic theory were finally refined by an Austrian physicist. He was the winner of the Nobel Prize in Physics in 1933 and the physicist’s name was Erwin Schrodinger.
Erwin Schrodinger made the theory of quantum mechanics or what is currently known as the “modern atomic model”. This atomic theory describes the nature of the movement and position of electrons based on the hypothesis of Broglie and Werner Heisenberg.
According to Louis de Broglie, the electron has a dual nature, that is, not only as a particle, but also as a wave. Meanwhile, Werner Heisenberg’s hypothesis is the uncertainty of the nature of electrons.
With Broglie and Heisenberg’s hypothesis, Erwin Schrodinger managed to find a wave equation for the movement of electrons in an atom. This formula can explain that the trajectory of electrons is a space, not just a line.
In summary, Erwin Schrodinger’s atomic theory or “modern atomic model” has several important points, viz
a) Atoms have a shell in which each shell and subshell.
b) The trajectory of electrons is a space not a line.
c) Waves are the movement of electrons in their trajectories.
d) The position of the electron cannot be determined with certainty.
e) The speed of the emitted wave is caused by oscillators that determine the emission of photons by the source.
f) Atoms that move as an oscillator will produce electromagnetic waves accompanied by a special wave frequency for the atom in question.