Jadon LeePeriod 6Due January 22/ 2018Periodic Table and Elements ReportHistory: The forming of the periodic table started from a Russian chemist named Dmitri Mendeleev in 1869. He put all the elements he knew and organized the chemical elements by atomic mass. Since his periodic table elements had disparate atomic masses, he predicted that there would be other elements found. Due to his prediction, he left spaces open in his periodic table for the elements were probably going to be found in the future. Radium and polonium were found by two French physicists, Marie and Pierre Curie, when they were working on the radiation of uranium and thorium. The noble gases were discovered by two British physicists, Sir William Ramsay and Lord Rayleigh, in 1894. J.J. Thomson, an English physicist, discovered negatively charged particles in an atom, called electrons, in a cathode ray experiment he conducted in 1897. However, the electron’s exact mass and charge were determined by John Townsend and Robert Millikan. In 1911, Hans Geiger and Rutherford found out that electrons orbit around the nucleus of an atom. Two years later, Bohr discovered that electrons move around a nucleus in orbitals. The first person to recognize protons in the atomic nucleus was Rutherford in 1914. Neutrons and isotopes were distinguished by James Chadwick in 1932. This was how the periodic came to find 118 elements from the first periodic table which identified 60 elements.Organization of the Periodic Table: Each element in the periodic table has its own box. In the box, there are letters and two numbers that identify the element. The number above the letters is the atomic number which represents the number of protons that element has. For the element iodine (shown above), the atomic number is 53. The letters in the box represent its atomic symbol. These two letters are abbreviations for the element’s name. The atomic symbol for helium (shown above) is I. Finally, the number in the bottom of the box is an element’s atomic mass number. This number is the weight of a single atom of the elements including its protons and neutrons. In the case of Iodine, its atomic mass number 126.9.In the periodic table, each vertical column is marked by a set of identifiers (3A, 4A, 1A, 2B). These columns are known as groups. The elements arranged in the columns are aligned that specific way because they share similar properties with each other. There are 18 groups in the periodic table. The specific grouping in the periodic table is alkali metals (group 1), alkaline earth metals (group 2), transition metals (groups 3-12), halogens (group 17)  and noble gases (group 18). In the bottom of the periodic table, there are elements that are separated from the actual, whole periodic table. The two types of elements that are unconnected to the table are called lanthanides and actinides. Elements 57 through 71 are called lanthanides. Lanthanides are called “f-elements” because they have valence electrons in their f shell. Actinides consists of elements 89 through 103. Similar to the lanthanides, they are also called the “f-elements” since they have valence electrons in the f shell. All actinides are radioactive. Alkaline earth metals have oxides that have basic alkaline solutions and high melting points. Transition metals are the elements that have their d subshell partly filled. Halogens are very chemically reactive. Noble gases are stable chemically and show similar properties of being colorless and odorless. Post-transition metals, metalloids, and nonmetals are groups, but they are not groups in columns. Post-transition metals are elements like aluminum and bismuth. The post-transition metals elements have similar characteristics of the transition metals, but the elements tend to be softer and conduct more inadequately than transition metals. Metalloids are elements like boron and antimony. The elements like boron, silicon, and geranium behave as semiconductors. Metalloids are also called “semi-metals.” Nonmetals are elements like hydrogen and selenium. In addition to the columns, the rows in the periodic table have a special meaning as well. Each row is called a period. All of the elements in the same period have the same number of atomic orbitals. Every element in the top row has one orbital for its electrons. The elements in the second row have two orbitals for their electrons. As the rows go down, every row adds an orbital to the one above it. There is a maximum of seven electron orbitals.In the periodic table, there are periodic trends Periodic trends are the patterns in the periodic table that show the different trend of a certain element (size and electronic properties). These trends include: electronegativity trends, ionization energy trends, electron affinity trends, and metallic character trends. Periodic trends are based on the arrangement of the periodic table which helps people predict an element’s properties. There are these kinds of trends because the elements’ similar atomic structure and their nature. Electronegativity is the atom’s ability to attract and attach with electrons. There is no systematized method to calculating electronegativity, but there is a common scale for measuring electronegativity through the Pauling scale. This is a trend on the periodic table, but it is only found on certain periodic tables (like the one shown below) *How the electronegativity table worksAnother type of trend is an ionization energy trend. Ionization energy is the energy that is needed to remove an electron from a neutral atom atom in its gaseous phase. Simply put, ionization energy is the opposite of electronegativity. On the periodic table, ionization energy increases from left to right. On the left side, there are elements that have low ionization energy. While on the right side, they have a higher ionization energy. *How the ionization trend worksThere is also an electron affinity trend in the periodic table. Electron affinity is the ability an atom has to accept an electron.  The more negative an atom’s electron affinity is, the higher an atom’s affinity is for electrons.Finally, the metallic character of an element is how willingly an atom is to lose an electron. Metallic character increases from right two left because the valence electrons’ and the nucleus’ desirability to come together is weaker which makes it easier to lose electrons. When going down a group in the periodic table, metallic character increases because the atomic size is increasing, meaning that the outer shells are farther apart. The electrons lose their “magnetism” to the nucleus which makes it easier to lose electrons.The elements in the periodic table are arranged in the way they are for a specific reason. In the seven periods, the atomic numbers increase left to right. Elements in the same row have the same number of electron shells. Elements in the same family also are arranged for a specific reason. The elements in the same column have similar properties.Structure of the Atom: Back then, we didn’t know as much about the atom as we do today. Since the discovery of the atom, a lot of knowledge has been learned about the atom and its structure. The first model of the atom was by John Dalton. When John Dalton made his model of the atom, the atom was not a well-known concept yet. When Dalton made his model of the atom, people didn’t know about electrons and the nucleus.J.J. Thomson found out that there were electrons inside atoms. Knowing that Dalton’s model wasn’t the most accurate model of the atom anymore, J.J. Thomson made his own model. His model is called the “plum pudding model.” The pudding of the atom was a positive charge and there were electrons that were floating on the soup. Still, we did not know about the nucleus or the placement of electrons in an atom.A scientist named Rutherford carried out experiments on the atom which changed the understanding of the atom. He found out that there was a dense, positively charged core in the atom called a nucleus which was surrounded by the electrons.There have been many advancements to the structure of the atom, but it wasn’t the most accurate yet. Rutherford’s atom model couldn’t explain some concepts of the atom like how an atom emits light at certain frequencies. So, Niels Bohr fixed/added to the atom model by putting the electrons at specific orbits at different energy levels around the nucleus.The atom is made of three main subatomic particles: the proton, neutron, and electron. Protons and neutrons are the subatomic particles that make up the nucleus. Neutrons have no electrical charge and helps to hold the protons together. Protons have a positive electrical charge. Elements have different characteristics based on the number of protons and neutrons an atom has in its nucleus. The subatomic particle that is said to “orbit” the nucleus is the electron. Electrons have negative charge and are on different energy levels around the nucleus. The electrons jump between levels when they lose or gain energy.Every single element has different electron configurations. Electron configuration of an atom is the number of electrons in each sub-energy level at the atom’s ground state. There is a specific way electrons enter the sub-levels. The way electrons enter sub-level are in order of increasing energy. For an electron to start filling the next sub-level, the previous sub-level needs to be filled or half-filled. There are many kinds of sublevels: s sub-level (two electron), p sub-level (six electrons), d sub-level (10 electrons), and the f sub-level (14 electrons).Valence electrons are at the outermost energy level of an atom. Valence electrons are the electrons which are responsible for and take part in chemical changes. The valence electrons in an atom also decide whether the atom combining will form ionic or covalent bonds. The elements that have the same number of valence electrons have similar chemical properties.Names and Characteristics of Each Group: Alkali metals is group 1 of the periodic table. It has the elements from Lithium to Francium. All the alkali metals have similar behavior and characteristics. Hydrogen is also group 1, but it does not have much characteristic of a metals, so it is often classified as a nonmetal. Group 2 of the periodic table are alkaline earth metals. It has the elements from Beryllium to Radium. These elements have high melting points and oxides with basic alkaline solutions. Transition metals are groups 3-12, including the lanthanides and actinides. Lanthanides are elements 57-71. These elements have similar chemical properties. Lanthanides are called the “f-elements” since they have valence electrons in their f shell. Actinides are elements 89-103. They are also called “f-elements.” Transition metals have partly filled d subshells. Post-transition metals are the elements aluminium, gallium, indium, thallium, tin, lead, and bismuth. Post-transition metals show some of the characteristics of the transition metals. They are softer and conduct more worse than transition metals. Metalloids are boron, silicon, germanium, arsenic, antimony, tellurium, and polonium. Metalloids sometimes are semiconductors. Halogens is group 17 of the periodic table from fluorine to astatine.Halogens are chemically reactive and are present in nature as mixed compounds than the elements itself. Noble gases is group 18 of the periodic table. Noble gases are chemically stable and have similar properties of being colorless and odorless.Works Cited”Water Treatment Solutions.” Lenntech Water Treatment & Purification, www.lenntech.com/periodic/history/history-periodic-table.htm.”File:Iodine.svg.” File:Iodine.svg – Wikimedia Commons, commons.wikimedia.org/wiki/File:Iodine.svg.Staff, Live Science. “How Are Elements Grouped?” LiveScience, Purch, 5 Apr. 2013, www.livescience.com/28507-element-groups.html.www.chem4kids.com/files/elem_pertable.html. Libretexts. “Periodic Trends.” Chemistry LibreTexts, Libretexts, 19 Nov. 2017, chem.libretexts.org/Core/Inorganic_Chemistry/Descriptive_Chemistry/Periodic_Trends_of_Elemental_Properties/Periodic_Trends.”Models Of The Atom.” Models Of The Atom | The Atom | Siyavula, www.siyavula.com/read/science/grade-10/the-atom/04-the-atom-02.Libretexts. “Periodic Trends.” Chemistry LibreTexts, Libretexts, 19 Nov. 2017, chem.libretexts.org/Core/Inorganic_Chemistry/Descriptive_Chemistry/Periodic_Trends_of_Elemental_Properties/Periodic_Trends.Electrons, www.nde-ed.org/EducationResources/HighSchool/Radiography/electrons.htm.Helmenstine, Ph.D. Anne Marie. “Electron Configuration Chart for the Elements.” ThoughtCo, www.thoughtco.com/electron-configuration-chart-603975.

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