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ATOM, John Dalton's Billiard Ball Model (1803), Joseph John…
ATOM
Atomic Models
This model stated that elements consisted of tiny particles called atoms. All the atoms that make up the element have the same mass. The chemical reactions involve the rearrangement of combinations of atoms, and all atoms of different substances have different weights.
According to this model, the positive charge is spread uniformly throughout the volume of sphere called pudding, while the negatively charged particles electrons called plums are distributed as point charges in shells.
When Rutherford shot a beam of alpha particles at a sheet of gold foil, a few of the particles were deflected which he believed was caused by the tiny, dense nucleus. This proved the existence of a small massive center to atoms, which would later be known as a nucleus of an atom.
Henry Moseley experimentally demonstrated that the major properties of an element are determined by the atomic number, not by the atomic weight, and firmly established the relationship between atomic number and the charge of the atomic nucleus.
This is a planetary model in which the negatively charged electrons orbit a small, positively charged nucleus similar to the planets orbiting the sun (except that the orbits are not planar). In his model, Bohr imagined the electron to move around the nucleus following fixed paths, or orbits.
James Chadwick have discovered the Neutron in atoms which are located in the center of an atom, inside the nucleus close by the protons. These neutrons believed to have neither a positive nor a negative charge.
This model proposes that electrons are almost as much like a wave of energy as they are like particles. They're moving so fast and they don’t have exact location at any given time.
A particle of matter that uniquely defines a chemical element. It is consists of a central nucleus that is usually surrounded by one or more electrons.
Atomic Structure
Subatomic Particles
Neutron
Proton
Represented by letter P or P+ that are found in the nucleus of atoms. It is a positively charged elementary particle that is a fundamental constituent of all atomic nuclei.
Electron
It is a stable subatomic particle with a negative electrical charge. It is believed to be truly fundamental, because it cannot be split into smaller particles, and it has no detectable structure.
It is a subatomic particle with no electric charge and are used to produce new isotopes. It has a mass of 1 and a charge of 0 that is slightly greater than that of a proton.
Democritus and Leucipus
They were right to suppose that the properties of materials depend not only on the nature of the constituent atoms or molecules, but also on the relative motions of these particles.
Plato
Plato introduced the atomic theory in which ideal geometric forms serve as atoms, according to which atoms broke down mathematically into triangles, such that the form elements had the following shape: tetrahedron, octahedron, icosahedron, and cube.
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Aristotle
He believed that all matter was made up either of one of the elements of water, air, earth, and fire or combinations of these four elements, with the exception of stars and planets which were made of aether.
Boyle
Dalton
Dalton’s atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. He stated that all compounds were composed of combinations of atoms and chemical reactions resulted in the rearrangement of the reacting atoms.
Lavoisier
He found out that the total mass of the products of a chemical reaction is always the same as the total mass of the starting materials consumed in the reaction.
Boyle was a great proponent of the experimental method who discovered that the volume of a gas decreases with increasing pressure and vice versa.
Proust
He first published the Law of Definite Proportions which states that a compound is composed of exact proportions of elements by mass regardless of how the compound was created.
Hayyan
Jabir Ibn Hayyan, also known as the Father of Arabic Chemistry, made alchemy into an experimental science based on the theory of nature and the four elements –fire, water, air, and earth.
Paracelsus
Paracelsus believed that the body's organs work was to separate impure substances in the body from pure substances or as a purifier. He also believed that maintaining the "tria prima", also known as the balance of mercury, is essential for having a good health.
Cations & Ions
It is defined as an atom or molecule that has gained or lost one or more of its valence electrons, giving it a net positive or negative electrical charge.
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The electrons in the outermost shell, or energy level, of an atom. It is responsible for the chemical properties of the atom.
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Two types of Ions
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Anion
It is negatively charged with more electrons than protons, because of their opposite electric charges.
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