The Atom – Introduction to fundamental concepts of Biological Science including the organization and common characteristics of living matters, cell structures and functions, food production by photosynthesis, harvesting energy, mechanism of cells reproduction, genetics, evolutions, and Human Biology. Introduction to general chemistry including basic concepts about matter, atomic structure, chemical bonds, gases, liquid, and solids, solutions, chemical reactions, acid, bases, and salt;
organic and biochemistry including hydrocarbons and their derivatives, carbohydrates, lipids, proteins, enzymes, vitamins, and minerals, nucleic acids; principles of physics and applications to nursing including gravity and mechanics, pressure, heat and electricity; nuclear chemistry and nuclear physics, effects of radiation on human beings, and protection and disposal. The aim of the course is to acquire knowledge and skills in general biological science, general chemistry and physics.
The Atom
Definition of Atom
An atom is the smallest constituent of matter that has properties of the chemical element itself. Every form of matter is it solid, liquid, or gas, contains atoms either neutral or charged.
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An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms.
Fundamental Particles
Atomic Particles of Matter
Protons and neutrons are heavier than electrons and reside in the nucleus at the center of the atom. Electrons are extremely lightweight and exist in a cloud orbiting the nucleus. The electron cloud has a radius 10,000 times greater than the nucleus, according to the Los Alamos National Laboratory.
Protons and neutrons have approximately the same mass. However, one proton is about 1,835 times more massive than an electron. Atoms always have an equal number of protons and electrons, and the number of protons and neutrons is usually the same as well. Adding a proton to an atom makes a new element, while adding a neutron makes an isotope, or heavier version, of that atom.
Nucleus
The nucleus was discovered in 1911 by Ernest Rutherford, a physicist from New Zealand. In 1920, Rutherford proposed the name proton for the positively charged particles of the atom. He also theorized that there was a neutral particle within the nucleus, which James Chadwick, a British physicist and student of Rutherford’s, was able to confirm in 1932.
Virtually all the mass of an atom resides in its nucleus, according to Chemistry LibreTexts. The protons and neutrons that make up the nucleus are approximately the same mass (the proton is slightly less) and have the same angular momentum, or spin.
The nucleus is held together by the strong force, one of the four basic forces in nature. This force between the protons and neutrons overcomes the repulsive electrical force that would otherwise push the protons apart, according to the rules of electricity. Some atomic nuclei are unstable because the binding force varies for different atoms based on the size of the nucleus. These atoms will then decay into other elements, such as carbon-14 decaying into nitrogen-14.
Here’s a simple drawing of the structure of an atom.
Protons
Protons are positively charged particles found within atomic nuclei. Rutherford discovered them in experiments with cathode-ray tubes that were conducted between 1911 and 1919. Protons are about 99.86% as massive as neutrons.
The number of protons in an atom is unique to each element. For example, carbon atoms have six protons, hydrogen atoms have one and oxygen atoms have eight. The number of protons in an atom is referred to as the atomic number of that element. The number of protons also determines the chemical behavior of the element. Elements are arranged in the Periodic Table of the Elements in order of increasing atomic number.
Three quarks make up each proton two “up” quarks (each with a two-thirds positive charge) and one “down” quark (with a one-third negative charge and they are held together by other subatomic particles called gluons, which are massless.
Electrons
Electrons are tiny compared to protons and neutrons, over 1,800 times smaller than either a proton or a neutron. Electrons are about 0.054% as massive as neutrons, according to Jefferson Lab.
Joseph John (J.J.) Thomson, a British physicist, discovered the electron in 1897, according to the Science History Institute. Originally known as “corpuscles,” electrons have a negative charge and are electrically attracted to the positively charged protons. Electrons surround the atomic nucleus in pathways called orbitals, an idea that was put forth by Erwin Schrödinger, an Austrian physicist, in the 1920s. Today, this model is known as the quantum model or the electron cloud model. The inner orbitals surrounding the atom are spherical but the outer orbitals are much more complicated.
An atom’s electron configuration refers to the locations of the electrons in a typical atom. Using the electron configuration and principles of physics, chemists can predict an atom’s properties, such as stability, boiling point and conductivity, according to the Los Alamos National Laboratory.
Neutrons
The neutron’s existence was theorized by Rutherford in 1920 and discovered by Chadwick in 1932, according to the American Physical Society. Neutrons were found during experiments when atoms were shot at a thin sheet of beryllium. Subatomic particles with no charge were released the neutron.
Neutrons are uncharged particles found within all atomic nuclei (except for hydrogen). A neutron’s mass is slightly larger than that of a proton. Like protons, neutrons are also made of quarks one “up” quark (with a positive 2/3 charge) and two “down” quarks (each with a negative one-third charge),
Timeline of Discovery of Fundamental Particles:
Scientists have long wanted to find the most basic building blocks of the universe. They asked, “what are the fundamental particles of matter that cannot be subdivided into smaller, simpler particles,” and “what holds these particles together?” The quest for fundamental particles began thousands of years ago.
Scientists thought they had finally found them when John Dalton discovered the atom in 1803 (see the timeline in Table below). The word atom means “indivisible,” and Dalton thought that the atom could not be divided into smaller, simpler particles.
Year: 1803
John Dalton discovers the atom
Year: 1897
J.J. Thomson discovers the electron, the first lepton to be discovered.
Year: 1905
Albert Einstein discovers the photon, the first boson to be discovered
Year: 1911
Ernest Rutherford discovers the proton, the first particle to be discovered in the nucleus of the atom.
Year: 1932
James Chadwick discovers the neutron, another particle in the nucleus
Year: 1964
Murray Gell-Mann proposes the existence of quarks, the fundamental particles that make up protons and neutrons.
Year: 1964-present
Through the research of many scientists, many other fundamental particles (except gravitons) are shown to exist.
For almost 100 years after Dalton discovered atoms, they were accepted as the fundamental particles of matter. But starting in the late 1890s with the discovery of electrons, particles smaller and simpler than atoms were identified. Within a few decades, protons and neutrons were also discovered. Ultimately, hundreds of subatomic particles were found.
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