...chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean-Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all. In 1858, German chemist August Kekulé observed that carbon often has four other atoms bonded to it. Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventually became known as valency; different elements bond with different numbers of atoms. In 1864, fellow German chemist Julius Lothar Meyer published a table of the 49 known elements arranged by valency. The table revealed that elements with similar properties often shared the same valency. English chemist John Newlands produced a series of papers in 1864 and 1865 noting that when the elements were listed in order of increasing atomic weight, similar physical and chemical properties recurred at intervals of eight; he likened such periodicity to the octaves of music.This Law of...
Words: 2708 - Pages: 11
...Periodic table From Wikipedia, the free encyclopedia Jump to: navigation, search This article is about the table used in chemistry. For other uses, see The Periodic Table. Standard form of the periodic table. The colors represent different categories of elements explained below. The periodic table is a tabular display of the chemical elements, organized on the basis of their atomic numbers and chemical properties. Elements are presented in increasing atomic number. The main body of the table is a 18 × 7 grid, and elements with the same number of valence electrons are kept together in groups, such as the halogens and the noble gases. Due to this, there are gaps that form four distinct rectangular areas or blocks. The f-block is not included in the main table, but rather is usually floated below, as an inline f-block would make the table impractically wide. Using periodic trends, the periodic table can help predict the properties of various elements and the relations between properties. As a result, it provides a useful framework for analyzing chemical behavior, and is widely used in chemistry and other sciences. Although precursors exist, the current table is generally credited to Dmitri Mendeleev, who developed it in 1869 to illustrate periodic trends in the properties of the then-known elements; the layout has been refined and extended as new elements have been discovered and new theoretical models developed to explain chemical behavior. Mendeleev's presentation also...
Words: 347 - Pages: 2
...The list, which included oxygen, nitrogen, phosphorus, mercury, zinc, and sulfur, was a basic outline for the modern periodic table. Russian chemist, Mendeleev, was the first scientist to construct a periodic table similar to the modern version. He organized elements according to increasing atomic mass and put columns of elements together that shared physical and chemical properties. He left blank areas for unknown elements whenever there was a large gap in atomic mass between two elements. He predicted the undiscovered elements’ properties, and when they were discovered they fit perfectly in the gaps. In 1864, Meyer published his own periodic table, unknown to Mendeleev. Meyer’s table consisted of 28 elements, classified by valence electrons. Unlike Mendeleev, Meyer did not predict new elements. English chemist, Mosley, “fixed” Mendeleev’s mistake by arranging elements by increasing atomic number instead of increasing atomic mass. He’s credited for developing the modern periodic table as well as forming periodic law, which states that when elements are arranged by increasing atomic number, there is a repeating pattern of their physical and chemical properties. According to periodic law, elements that are in the same group have the same number of valence electrons and reoccurring trends in their physical and chemical properties. The four trends caused by periodic law and valence electrons are atomic radii, ionic radii, ionization energy, and electronegativity. The first one, atomic...
Words: 1117 - Pages: 5
...English – The Periodic Table Online Summary The Periodic Table' gives an insight into the importance of chemistry in Levi's life. On a very basic level it probably saved him at Auschwitz, where his professional experience meant he was selected for work in one of the IG Farben synthetic rubber factories attatched to the concentration camp ('Cerium') - far preferable to the back-breaking physical labour he would otherwise have had to perform. Chemistry also provided Levi with a living before and after the war. But Levi looked for more than simply 'the tools to earn his living and have a secure life.' In 'Hydrogen' Levi expresses what chemistry meant to him as a school boy: 'An indefinite cloud of future potentialities'...from which 'cloud I expected my law, the principle of order in me, around me and in the world.' In 'Iron', as a chemistry degree student and with the war looming with all the terrible consequences that it would have for him, Levi explains to his friend Sandro how his view of chemistry has developed: Sandro was surprised when I tried to explain to him some of the ideas that at the time I was confusedly cultivating. That the nobility of man, acquired in a hundred centuries of trial and error, lay in making himself the conquerer of matter, and that I had enrolled in chemistry because I wanted to remain faithful to this nobility. That conquering matter is to understand it, and understanding matter is necessary to understanding the universe and ourselves: ...
Words: 786 - Pages: 4
...especially chemists know what is it periodic table. If we ask someone a question about the creator of the periodic table, he/she will answer us that this was Mendeleev, because modern periodic table has name “D. I. Mendeleev Periodic table”. But is he really was the creator of the periodic table? If no, who was? And why people modernized Mendeleev’s periodic table? All this questions are very interesting, and I will try to explain answers on them, to understand the importance of the periodic table in our time. First of all, let’s take a look on the history of the formation of periodic table. This is strange, but the one who began to place chemicals in order was not Mendeleev. It was Alexandre Béguyer de Chancourtois.It doesn’t mean that he made P.T, but he made a very significance step in the...
Words: 835 - Pages: 4
...The periodic table is a table in which all of the known elements are listed. The table arranges the elements in order of increasing proton number to show the similarities of chemical elements. Therefore elements with structural similarities & atomic number are placed together. These elements can be placed into two different categories, metals & non-metals. These elements can then be sub divided into 4 groups; Alkali, non-metals, transition & inner-transitions. If read horizontally the size of the atoms increases from metals to non-metals, yet when read vertically, all of the elements in the same group have the same number of electrons, which means they all behave in the same manner. The first man to describe the periodic table was Dmitri Ivanovich Mendeleev, whom was interested in chemistry. Mendeleev was determine to prove that elements in fact followed certain patterns. Mendeleev used the properties of the 57 known elements to group them. He used the first version of the periodic table to place elements where they seemed to belong. He also left blank spaces in the appropriate squares. After the elements had been laid out he was able to, in detail, predict the chemical & physical tendencies of the elements. Hydrogen didn’t fit into his pattern so he put it in a box of it’s own. A new row was started each time an element was discovered with properties similar to those in the first row. When read top to bottom there are various similarities to be found in the table, identicalas...
Words: 454 - Pages: 2
...to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all. In 1858, German chemist August Kekulé observed that carbon often has four other atoms bonded to it. Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventually became known as valency; different elements bond with different numbers of atoms. In 1864, fellow German chemist Julius Lothar Meyer published a table with 44 elements arranged by valency. The table showed that elements with similar properties often shared the same valency. English chemist John Newlands produced a series of papers in 1864 and 1865 noting that when the elements were listed in order of increasing atomic weight, similar physical and chemical properties recurred at intervals of eight; he likened such periodicity to the octaves of music. This Law of Octaves, however, was ridiculed by Newlands' contemporaries, and the Chemical Society refused to publish his work.Newlands was nonetheless able to draft a table of the elements and used it to predict the existence of missing elements, such as germanium. The...
Words: 311 - Pages: 2
...Although Dmitri Mendeleev is often considered the "father" of the periodic table, the work of many scientists contributed to its present form. In the Beginning A necessary prerequisite to the construction of the periodic table was the discovery of the individual elements. Although elements such as gold, silver, tin, copper, lead and mercury have been known since antiquity, the first scientific discovery of an element occurred in 1649 when Hennig Brand discovered phosphorous. During the next 200 years, a vast body of knowledge concerning the properties of elements and their compounds was acquired by chemists (a 1790 article on the elements). By 1869, a total of 63 elements had been discovered. As the number of known elements grew, scientists began to recognize patterns in properties and began to develop classification schemes. Law of Triads In 1817 Johann Dobereiner noticed that the atomic weight of strontium fell midway between the weights of calcium and barium, elements possessing similar chemical properties. In 1829, after discovering the halogen triad composed of chlorine, bromine, and iodine and the alkali metal triad of lithium, sodium and potassium he proposed that nature contained triads of elements the middle element had properties that were an average of the other two members when ordered by the atomic weight (the Law of Triads). This new idea of triads became a popular area of study. Between 1829 and 1858 a number of scientists (Jean Baptiste Dumas, Leopold...
Words: 1914 - Pages: 8
...Most igneous rocks contain the third element on the periodic table, lithium. Discovered in 1817, and in multiple alloys, it is the first metal on the periodic table. It is the least reactive metal when it comes to water, but also the lightest alkali metal. When in its pure form it is soft enough even a butter knife could cut it. Lithium was first discovered in the ore petalite by the chemist Johan Arfvedson in the 1817’s. The mineral petalite has a crimson flame which led Johan to believe that this element is what gave it that color, which it does. Though Arfvedson could not isolate the lithium; it was later done by Augustus Matthiessen and Robert Bunsen. They managed to purify lithium from lithium chloride in 1855 using electricity....
Words: 329 - Pages: 2
...In this lab, we explored some of the ideas that allowed Dmitri Mendeleev to publish his periodic table in 1869 including the findings of Johnann Dobereiner, John Newland and Lothar Meyer. This lab was completed utilizing element cards that displayed the name, atomic number, atomic mass and chemical formulas of the 64 elements that were known in the nineteenth century. We began by examining Dobereiner’s Triads by arranging the triads in order of atomic mass then calculated the average of the first and third element and compared it to the middle element. In the case of chlorine (35.5amu), bromine (80amu) and iodine (127amu), the average of chlorine and iodine is 81.3amu, which is very close to the atomic mass of bromine. We discovered this is...
Words: 381 - Pages: 2
...Diversity: Awareness and Opportunities at Appling County High Tonya D. Adams Western Governors University A. Introduction Appling County High School is a well-known high school, located in rural Southeast Georgia. The sound curriculum is challenging as well as the heart of education and requires the integration of multiple learning outcomes. The school has e enrolled students and 61 faculty members. In recent years the demographics have become more economically diverse, to which has led to an increase of challenges for the entire community as well as those in the education system. A1. Local Demographics One major demographic change we see occurring in the U.S. as well as here at ACHS is the gender of teachers is predominately female. I can recall just a handful of male teachers during my years while enrolled in the public school system. During 2011-2012, 76 percent of public school teachers were female. This makes me wonder where all the men are. I suppose as females we tend to be more of the “motherly” type and have the ability as well as necessary skills to cope with being around children at least 8 hours each day. Perhaps men can earn a larger salary by working in other fields and not having the constant reminder of being a parent while at work. In addition to having more female teachers or educators, we also have an increase in the number of students who speak another language in addition to English. The number of refugees moving into the United States is...
Words: 816 - Pages: 4
...Part I: Atomic Radius Trend Going Across the Periodic Table Part II: Atomic Radius Trend Going Down a Group Part III: Analysis and Conclusion 1. Refer to the graph that you created in Part I of this assignment. Describe the general trend or patterns that you observed in the atomic radius as you go across the periodic table. (2 points) · The general trend I observed is that as the atomic number increases, the atomic radius decreases. So, there is a decrease in atomic radius from left to right across the period. 2. In Part II of this assignment, you graphed the atomic radius of some elements from group 14 on the periodic table. What is the general trend for atomic radius going down that group? (2 points) · The general trend going down Group 14 is that as the periodic number increases, so does that atomic radius. So, there is a increase in atomic radius going down the group of elements on the periodic table. 3. What element in Period 5 of the periodic table is a member of Group 14? (1 point) · The element Tin is in Period 5 of the periodic table and is a member of Group 14. 4. The word interpolate means to use a given line graph to find unknown points between the plotted points of the graph. Use your line graph from Part II to interpolate, or estimate, atomic radius of Tin (Sn). (1 point) · The estimated atomic radius of Tin is 147. 5. Tin’s actual atomic radius is 140 pm. Use the math equation below to determine the percent error of your estimated value. (2 points)...
Words: 360 - Pages: 2
...Chapter 5: Properties of Matter Matter is anything that has a mass and takes up space. The particle theory of matter is a theory that describes the composition and behavior. Matter can be many up of many different particles or only one. A pure substance is a type of matter that consists of only one type of particle. Then there are mixtures that are made up of at least two different types of particles. There are two different types of mixtures; mechanical mixtures and solutions. A mechanical mixture is a mixture in which the substances in it are distinguishable from each other, either with the unaided eye or a microscope. A solution looks like a pure substance but it contains more than one type of particle. Alloys are when two or more metals are mixed together. A physical property is a characteristic of a substance that can be determined without changing the composition of that substance. A qualitative physical property is not measured and includes hardness, malleability and electrical conductivity. Quantitative physical properties are measured and include temperature, height and mass. A physical change is a change is which the composition of the substance remains unaltered and no new substances are produced Examples of physical change are a change of size or shape, a change of state, and dissolving. A chemical property is a property of a substance that describes its ability to undergo changes to its composition to produce one or more new substances. A chemical; change is a...
Words: 1355 - Pages: 6
...Background: The Disappearing Spoon written by Sam Kean, informs readers about the importance of the periodic table and how it is important than what people really believe. In this book he talks about how the periodic table is not a table with numbers and letters. It is full of stories and interesting facts, which makes it standout. This book is more likely written for science and chemistry student and can not leave out the outstanding teachers for example Mrs. Nix. Summary: The reason Sam Kean wrote the book the way he did was because, he is trying to tell us that the period table is not just a table. There are so many things behind the periodic table than just numbers and letter. He has a story behind almost every element on the period...
Words: 381 - Pages: 2
...Honors Chemistry Chapter 2 Success Sheet This success sheet is filled with questions and prompts that will guide you as you prepare for the Chapter 2 test. Write your answers to each question on a separate sheet of paper. Chapter 2 – Activity 1 1. What is a pure substance? 2. Explain the difference between an element and a compound. 3. How can a mixture of salt, sand, and iron filings be separated? 4. What kind of separation is needed to change a compound into its elements? 5. What do the subscripts mean in a chemical formula? Chapter 2 – Activity 2 6. Explain what happens to the energy of particles as a substance is heated form a solid to a liquid to a gas. 7. Explain what happens to the temperature of particles as a substance is heated from solid to liquid to gas. 8. What happens to the volume of a gas as it is heated? 9. Explain why dry ice sublimates at room temperature. What is the identity of the white vapor that is observed? 10. Draw a heating curve for water and label the following: solid, liquid, gas (vapor), melting, freezing, vaporization, condensation. 11. Explain sublimation and deposition. Chapter 2 – Activity 3 12. What is a solution? Name at least 3 properties of a solution. 13. What is a suspension? Name at least 3 properties of a solution. 14. What is a colloid? Name at least 3 properties of a solution. 15. How can a suspension be separated? 16. Give an example of a solution, a suspension, and a colloid...
Words: 583 - Pages: 3
