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Summary of Biology Chapter
Chemistry is largely defined as a subject that deals with matter in terms of their composition, and the manner in which these different forms of matter interrelate amongst each other. Note that every material and immaterial object that has mass as well as occupies space is termed as matter. Scholars have discovered that matter comprises of various combined elements that serve as the building blocks for larger particles known as atoms. Elements, being the basic unit of matter, subsist in a fundamental and pure structure and thereby the inability of one to modify them into smaller particles. Examples of elements include gold, iron, hydrogen, aluminum, and oxygen, amongst others. A comprehensive list of all present elements is presented in a tabular grid referred to as the periodic table that comprises of 118 elements, set in an orderly way.
Elements are considered the central units from which all forms of matter present in the earth are created. Both helium and hydrogen are very significant in the formation of matter, as they constitute the highest proportion of all present natural elements within the earth’s surface whereas oxygen accords preeminence on earth’s crust. Therefore, it is good to note that the earth and all creatures are as a product of the combination of such elements. The blending of elements in matter formation is known as a reaction; this is achieved through atomic combinations of the various elements involved. An atom comprises of a focal point that constitutes the innermost part, known as the nucleus. Further, the nucleus comprises of protons, neutrons and electrons.
Protons are positively charged, neutrons are negatively charged whereas the neutrons possess no charge. The number of protons is always equal to that of the neutrons, therefore both particles are jointly attached to each other within the nucleus. The electrons on the other hand, are situated outside the nucleus in compartments known as shells. Hydrogen is the simplest atom, comprising of a single proton within its nucleus. When the number of protons is equal to that of electrons, the charges neutralize each other and the atom is considered a neutral atom. The periodic table begins with the smallest atom in terms of the atomic number and moves gradually to those elements with a high atomic number. The first element is placed on the left hand side of the table and subsequent elements follow on the right hand side.
The horizontal grids created by the arrangement are termed periods whereas the perpendicular grids are termed groups. The atomic names are not given in full within the periodic table; only one or two letter characters with the mass number placed as a superscript are given. For instance, hydrogen is named simply as H since its mass number is 0. Another important measure is the atomic number which reflects the amount of protons present in an atom. Unlike protons that tend to be fixed, neutrons tend to fluctuate for some elements that are known as isotopes. The variant neutrons lead to varying mass numbers for a given element and therefore necessitate the inclusion of all mass and atomic numbers present for identification purposes.
Due to the varying nature of isotopes, some are considered unstable due to their behavior, noted in the emission of charges until a stable state is acquired. These types of isotopes are referred to radioisotopes and are extremely helpful to the medical field in terms of research. To review atomic combinations, we will use water, which is written as H2O. The formula simply indicates that two atoms of hydrogen combine with a single atom of oxygen for the creation of a water molecule that resembles a testicle in terms of structure. The chemical link in the process is attributed to hydrogen ions written as H and hydroxyl ions written as OH. H2O is therefore a denotation of the water molecule, with a weight of 18 grams or 1 mole. To understand this chemical combination, remember that both protons and electrons are charged particles. With the nucleus being positively charged, it draws the electrons towards itself.
Because electrons are housed in shells, it is important to note that upon the filling of a given shell, another is added for housing of the other electrons. Shells are therefore energy levels due to the electron charges, and those in close proximity to the nucleus are less charged. An atom is considered as stable once its outermost energy level (shell) is completely occupied by electrons. When atoms have an unfilled outer shell, it combines with other atoms to obtain the required number of electrons, which constitutes the chemical bond. Three chemical bonds are used by atoms in a bid to acquire stability. The initial one is known as the covalent bond and is a type of shared bond between two or more atoms. The ionic bond is the second type of atomic link, created through the combination of ions bearing different charges. Last is the hydrogen bond that occurs when differently charged areas of the polar molecule combine.
All forms of life are sustained by the water molecule, which aids in the adjustment of body heat. This is achieved through a chemical process that begins with the exposure of water to air, leading to the dissociation of hydrogen bonds within the water molecule, allowing the uncombined water to turn into vapor. The dissociation is activated by energy acquired from the body and conveyed through the blood stream. As the blood comes into contact with the skin, sweat is generated and as some of it is lost in terms of vapor, a cooling effect is created. Acids are good sources of hydrogen ions whereas bases tend to acquire such ions into their structures. The number and strength of hydrogen ions in a given solution are determined by the pH scale. Blood has a pH of 7.4 and all fluids present within the body are stabilized by the use of buffers. In fact, the higher the concentration of buffers within a given solution the more stable it becomes in terms of pH.
Energy within the body is synthesized through the chemical separation of fats/lipids. Lipids are actually insoluble components in water and therefore cannot combine as reflected by other atoms. The most energetic form of lipids is known as triglyceride. Other than energy creation, lipids are also a significant constituent of body cells, for instance, phospholipids constitute a major part of the cell membrane. Another important constituent of body cells is the genetic matter that is stored within the DNA. The DNA’s primary function within the body in terms of cell processes is the management and direction of every activity conducted within the cell. Once the directions are released by the DNA, the execution process is instituted and monitored by the RNA. Although within a normal body the DNA plays the primary role whereas the RNA serves the secondary role, in a number of viruses, the RNA is preeminent thereby serving both roles. This occurs in cases where the RNA constitutes the genetic matter.
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