...700-word paper in which you describe the periodic nature and properties of atoms and molecules. Explain at a level of detail Dmitri Mendeleev would have understood how halogens and alkali metals are extremely reactive, whereas noble gases are not reactive. Compare properties of molecules formed from atoms in similar families; for example, H2S versus H2O. Explain what is meant by the electronic structure of atoms. How does knowing the electronic structure of atoms aid chemists in predicting chemical reactions? Periodic Table is designed to help us understand how elements are going to react to each other and also gives us the breakdown of how many atoms are in each element. This chart also helps us to identify metals, liquids, and gases. This chart shows us the atomic mass and structure of each element. Knowing this information allows us to determine which elements can bond and interact with each other. Alkali metals and halogens can form ionic bonds easily which involves the transfer of an electron from an atom of metal forming a positively charged species, to an atom of non-metal forming a negatively charged species. These two species interact electrostatically and form one of the two extreme forms of bonding; covalent bonding is the other extreme form (Kostiner & Jespersen, 2003). Electronic structure is another piece of important information that you will find on the Periodical Table, this is the atomic number and it will tell you how many atoms make up the element. Alkali...
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...Lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths. Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together in a triad as soft. German 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 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...
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...Chemical periodicity Lorem V. Mendoza ------------------------------------------------- .ABSTRACT ------------------------------------------------- When elements are arranged in the order of increasing atomic number, their physical and chemical properties recur periodically. This periodicity stems from the valence electronic configurations of the elements. This arrangement of the elements on the order of increasing atomic number with the elements having similar properties placed in vertical columns is known as the periodic table. INTRODUCTION This Experiment is all about for determining the given compound. In this Experiment we try to observe the physical state, color, appearance and the reaction of a compound on a litmus paper. MATERIALS AND METHODS In this experiment, we use Test tubes to observe the difference between the elements. 10 ml graduated cylinder to measure the water. Spatula, we used this to put the elements on the test tubes. We used Litmus Paper to determine maybe acid or base the elements. On this Activity, We try to identify the Physical state, Color, and Appearance of different elements. Li2 CO3 K2CO3 CaCO3 Na2CO3 MGCO3 BaCO3 On the first Procedure, We put a small amount of a elements samples Li2CO3 , K2CO3, CaCO3, Na2CO3, MGCO3 and BaCO3 in the different test tubes. We put 10ml water on the different test tubes. After adding we stir it and observe. We use a Litmus Paper to determine the elements maybe acid or base. On the Second...
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...introduction of contaminants into the natural environment that causes adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollution also has different components call Pollutants. (Wikipedia 2012) A pollutant is substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. A pollutant may cause long- or short-term damage by changing the growth rate of plant or animal species, or by interfering with human amenities, comfort, health, or property values. (Wikipedia 2012) There are also different kinds of pollutants like greenhouse gases, pesticides, endocrine disruptors, petroleum and heavy metals. Carbon dioxide and methane are two of the most important of these gases, called greenhouse gases because they trap heat in the earth's atmosphere. This is already causing severe problems around the world and the situation will only get worse. The rising temperatures will likely lead to more severe weather events, which cause shifts in natural communities, and probably lead to greater species extinction rates, among numerous other effects. Pesticides are a broad group of chemicals that enable us to live more comfortable lives by and large, but whose main purpose underlies the central problem with pesticide pollution. They are all poisons. A lot of these chemicals will wash into our rivers and streams and cause direct toxicity to fishes, and may work their way up the food...
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...Name Lab Section Date The Mole Concept and Atomic Weights Text Reference: Tro, Chemistry: Structure and Properties Section 2.8 - Atoms and the Mole: How Many Particles? Section 1.9 – Atomic Mass: The Average of an Element’s Atoms The purpose of this activity is to better understand the concepts of relative atomic mass, counting by weighing and the mole. Per cent composition and average atomic mass are included. Part I. Relative Atomic Masses and the Mole – Early Method When John Dalton proposed his atomic theory, he stated that the atoms of each element had a characteristic mass. He carried out experiments to determine the relative atomic mass of each element. To do this, he had to establish a standard because a single atom was too small to weigh. The standard he chose was that the mass of hydrogen would be set equal to 1.000. In a simple experiment, Dalton would measure the grams of an element such as sulfur that reacted with 1.00 gram of hydrogen. For sulfur, the reacting mass was found to be 32.0 grams, and so 32.0 was the relative mass of sulfur with respect to the standard hydrogen. (Note: The current standard for atomic mass is the most abundant isotope of carbon, C-12, with an assigned mass of exactly 12.000 amu.) The following activity will demonstrate how the relative mass method works. 1. Weigh five of the red color balls to three decimal places. Be sure to tare out the mass of the plastic cup. Record the mass in the table below. 2. Weigh five...
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...1789, Antoine Lavoisier published a list of 33 chemical elements, grouping them into gases, metals, nonmetals, and earths; Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties.Lithium, sodium, and potassium, for example, were grouped together in a triad as soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third; this became known as the Law of Triads. German 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...
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...In 1789, Antoine Lavoisier published a list of 33 chemical elements, grouping them into gases, metals,nonmetals, and earths.[42] Chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together in a triad as soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third;[43]this became known as the Law of Triads.[44] German 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.[43] 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.[45] In 1862, Alexandre-Emile Béguyer de Chancourtois, a French geologist, published an early form of periodic table, which he called the telluric helix or screw. He was the...
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...year 1800 Dalton presented a paper which was on the constitution of mixed gasses. This would lead him to develop his gas law and also affect others, such as Charles and Gay-Lussac. This research would also lead him to research atomic weights, which lead to his contribution in 1805. Dalton theorized that elements are made of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass and other properties. Atoms cannot be subdivided, created, or destroyed. Atoms of different elements combine in simple whole-number ratios to form chemical compounds. In chemical reactions, atoms are...
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...how Mendeleev arranged the elements, known at that time, in a periodic table by using properties of these elements and their compounds and used his table to predict the existence and properties of some elements not then discovered ● Classify elements as metals or non-metals according to their position in the periodic table ● Describe the structure of an atom as a nucleus containing protons and neutrons, surrounded by electrons in shells (energy levels) ● Demonstrate an understanding that the nucleus of an atom is very small compared to the overall size of the atom ● Describe atoms of a given element as having the same number of protons in the nucleus and that this number is unique to that element ● Recall the relative charge and relative mass of a proton, a neutron and an electron ● Demonstrate an understanding that atoms contain equal numbers of protons and electrons ● Explain the meaning of the terms, atomic number, mass number and relative atomic mass ● Describe the arrangement of elements in the periodic ● Demonstrate an understanding that the existence of isotopes results in some relative atomic masses not being whole numbers ● Calculate the relative atomic mass of an element from therelative masses and abundances of its isotopes ● Draw the electronic configurations of the first 20 elements in the periodic table as diagrams and in the form 2.8.1 ● Describe the connection between the number of outer electrons and the position of an element in the periodic table ...
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...Physical properties of Elements & chemical properties of Elements Purpose- The purpose of this lab is to look closely at properties that differentiate metals from nonmetals, and then to see how the reactivity of metals differ within a group and within a period Procedure- (Part 1). First you must put on googles because we are working with chemicals that could damage your eye sight if got in eye. Then you obtain a spot plate and obtain 1 sample of each element and be sure not to use your fingers while doing this. Next you get a conductivity tester, then observe elements and record color, whether the element is malleable or brittle, and if it conducts electricity. After that you identify if the sample is a metal, nonmetal, or metalloid. Lastly you clean up your area and return the nonmetals and the conductivity tester. (Part 2). The first step is you must have googles on. You then return all the nonmetals, and get one more sample of each metal, but do NOT use your fingers. Then record your observations about each metal in data table 2. After that clean out your spot plate then place spot place over a blank piece of paper, next locate three wells that are not adjacent to each other and label them as magnesium, aluminum, and calcium. Your next step is to add 10 drops of distilled water to the three well and then add 1 drop of litmus to each well too then record the color of the liquids in the data table. Also add 1 piece of the appropriate metal to the wells and record...
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...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...
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...Silicon Silicon is an element in the periodic table. Silicon is a metalloid, which means it has both properties of a metal and non-metal, so it is a member of Group 14(IVA)/the carbon family. Its atomic number is 14, its atomic mass is 28.0855 and its density is 2.65g/cm3. Silicon is a solid at room temperature with a boiling point of 3265⁰ C and a melting point of 1414⁰ C. Silicon exists in two allotropic forms, which means it has two forms that have different physical and chemical properties. The amorphous form is a brown powder and the crystalline form has a metallic luster and a grayish colour. Silicon is very hard, very brittle and is a semiconductor, meaning it is able to allow an electrical current pass through it better than a non-conductor, like glass or rubber, but not as good as a conductor, like copper or aluminum. Silicon always occurs as a compound, so it is always combined with other elements. Silicon dioxide is the most abundant compound in the earth’s crust, most commonly taking the form of sand. This compound is used in the manufacture of glass and bricks, paper and rubber, as a food additive, as an insulating material, in cosmetics, and many more! The compound of silicon with other elements like boron, gallium or arsenic is used in the making of electronic devices such as transistors, rectifiers, microchips, etc. Silicon carbide is one of the hardest substances known which can be used as an abrasive or as a refractory material. Silicones, which include silicon...
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...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 Gmelin, Ernst Lenssen, Max von Pettenkofer, and J.P. Cooke) found that these types of chemical relationships extended beyond the triad. During this time fluorine was added to the halogen...
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...1. How many elements are essential? a. Approximately 20-25% of the 92 natural elements are considered essential, this is about 17-25 elements. 2. Which elements make up 96% of matter on earth? a. The four elements that make up 96% of all matter are the elements oxygen (O), hydrogen (H), nitrogen (N), and carbon (C). 3. What subatomic particles are found in the atomic nucleus? What are their charges? a. There are three subatomic particles found in an atom’s nucleus and they are electrons, protons, and neutrons. Both electrons and protons are electrically charged, electrons are negatively charged and protons are positively charged. The neutron has no electrical charge at all, lending to its name. 4. Explain matter’s state of potential energy....
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...Chlorine What is Chlorine? Chlorine is a Chemical element with the atomic number of 17 and symbol Cl. The Chemical formula for Chlorine is Cl2. The element can be found in a liquid, gas, or solid state. When the element is in gas form, it has a strong odor and can be toxic/poisonous. When Chlorine is in a liquid or solid form, it’s used for bleaching, disinfecting and oxidizing agent. Who discovered it and when was it discovered? The element was first discovered when Carl Wilhelm Scheele (a Swedish Chemist) combined MnO2 (Pyrolusite) and HCl (hydrochloric acid) in 1774. Gas was produced in this reaction. Scheele assumed that the gas contained oxygen. In 1810, Chemists believed that the gas might be a pure element. This was confirmed by Sir Humphry Davy. How is Chlorine formed and how do we get it? Chlorine is not...
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