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Grouping Elements with Similar Chemical Properties Together Essays

Grouping elements with similar chemical properties together Date: 4. 10. 2012 Objectives The objective of this experiment is to experimentally investigate which elements show similar chemical properties. Chemical principle Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a dull gray, silver solid under standard conditions. Calcium atoms have an electron configuration of (2, 8, 8, 2) and 2 outermost shell electrons. Calcium is in group 2 and period 4 of the periodic table. Calcium commonly forms the cation Ca2+ by donating 2 electrons, reaching a stable electron configuration.
Calcium is an alkaline earth metal. Magnesium is a chemical element with symbol Mg and atomic number 12. Magnesium is a shiny gray solid under standard conditions. Magnesium atoms have an electron configuration of (2, 8, 2) and 2 outermost shell electrons. Magnesium is in group 2 and period 3 of the periodic table. Magnesium commonly forms the cation Mg2+ by donating 2 electrons, reaching a stable electron configuration. Magnesium is an alkaline earth metal. Copper is a chemical element with symbol Cu and atomic number 29.
Copper is red orange metallic luster under standard conditions. Copper atoms have an electron configuration of (2, 8, 18, 1) and 1 outermost electron. Copper commonly forms the cation Cu2+ by donating 2 electrons. Copper is in group 11 and period 4 of the periodic table. Copper is a transition metal. Calcium and magnesium have the same number of outer shell electrons and similar electron configurations. They are both in group 2 and have similar chemical properties. Copper has a very different number of outer shell electrons and electron configuration from magnesium and calcium.
Copper is instead in group 11 and has very different chemical properties compared to magnesium and calcium. Hydrochloric acid is an acidic compound with the chemical formula HCl. A hydrochloric acid molecule consists of a hydrogen atom H and a chlorine atom Cl, bounded by a single covalent bond. Covalent bonds are a type of chemical bonding involving the sharing of pairs of electrons. Single covalent bonds are covalent bonds where one pair of electrons are shared, double covalent bonds are bonds where two pairs are shared, and this meaning extends to all other positive integers.
Hydrochloric acid is very soluble in water and its solution in water is pale green. When magnesium is mixed with a hydrochloric acid solution, hydrogen chloride molecules ionize into ions H+ and Cl-. Magnesium ionizes into Mg2+ ions, transferring its electrons to hydrogen atoms. The hydrogen atoms then form single covalent bonds with each other, escaping as the diatomic, meaning with two atoms, gas H2. Magnesium and chlorine form the compound MgCl2. The compound is held together by a strong electrostatic force between the ions Mg2+ and Cl-.
This type of chemical bonding involving the strong electrostatic attraction between ions is termed ionic bonding. This reaction can be summarized by the word equation: hydrochloric acid + magnesium > magnesium chloride + hydrogen Reactions like this, involving transfers of electrons or changes in oxidation states, are called redox reactions. Oxidation state refers to the hypothetical charge an atom would have if all bonds to atoms of different elements were completely ionic. Oxidation refers to an increase in oxidation state and oxidants refer to chemicals which cause other substances to become oxidized.
Similarly, reduction refers to the decrease in an oxidation state and reductants refer to chemicals which cause other substances to become reduced. In this reaction, magnesium is initially neutral and the hydrogen ions from hydrochloric acid are initially positive. Then, magnesium transfers its electrons to the hydrogen ions. Thus, in this reaction magnesium is the reductant and hydrochloric acid is the oxidant. Calcium, since it has very similar chemical properties with magnesium, reacts with hydrochloric acid solutions in a very similar fashion.
This reaction is also redox and can be summarized by the word equation: hydrochloric acid + calcium > calcium chloride + hydrogen However, copper, having very different chemical properties to calcium and magnesium, does not react with hydrochloric acid solutions at all. Chlorine is a chemical element with symbol Cl and atomic number 17. Chlorine is a pale yellow, green gas under standard conditions. Chlorine atoms have an electron configuration of (2, 8, 7) and 7 outermost shell electrons. Chlorine is in group 17 and period 3 of the periodic table. Chlorine ommonly forms the anion Cl- by receiving an electron, reaching a stable electron configuration. Chlorine is a halogen. Bromine is a chemical element with symbol Br and atomic number 35. Bromine is a red, brown liquid under standard conditions. Bromine atoms have an electron configuration of (2, 8, 18, 7) and 7 outermost shell electrons. Bromine is in group 17 and period 4 of the periodic table. Bromine commonly forms the anion Br- by receiving an electron, reaching a stable electron configuration. Bromine is a halogen. Iodine is a chemical element with symbol I and atomic number 53.
Iodine is a lustrous, metallic gray solid under standard conditions. Iodine atoms have an electron configuration of (2, 8, 18, 18, 7) and 7 outermost shell electrons. Iodine is in group 17 and period 5 of the periodic table. Iodine commonly forms the anion I- by receiving an electron, reaching a stable electron configuration. Iodine is a halogen. Sulphur is a chemical element with symbol S and atomic number 16. Sulphur is a lemon yellow solid under standard conditions. Sulphur atoms have an electron configuration of (2, 8, 6) and 6 outermost shell electrons. Sulphur is in group 16 and period 3 of the periodic table.
Sulphur is a nonmetal. Chlorine, bromine, and iodine have the same number of outer shell electrons and similar electron configurations. They are both in group 17 and have similar chemical properties. Sulphur has a very different number of outer shell electrons and electron configuration from chlorine, bromine, and iodine. Sulphur is instead in group 16 and has very different chemical properties compared to chlorine, bromine, and iodine. Sodium sulphite is a salt with the chemical formula Na2SO3. Sodium sulphite consists of two sodium ions Na+ for each sulphite ion SO32-, held together by an ionic bond.
Sodium sulphite is soluble in water and its solution in water is colorless. When chlorine solution is mixed with sodium sulphite solution, water ionizes into ions H+ and OH-. Chlorine reacts with hydrogen ions in the presence of electrons to form HCl and sulphite ions react with hydroxyl ions, forming sulphate ions SO42-, a hydrogen ion, and two electrons. Although each of these two reactions cannot be done separately since they involve an unbalances of electrons, they can be conducted together, since when done so, the electron unbalances cancel out. Thus this reaction involves the transfers of electrons so it is a redox reaction. he resulting solution will become HCl and NaSO4, both of which are colorless. This reaction can be summarized by the word equation: chlorine solution + sodium sulphite solution > hydrochloric acid solution + sodium sulphate solution Since bromine and iodine have very similar chemical properties to chlorine, they react with sodium sulphite solution in a very similar fashion. The reactions are also redox and can be respectively summarized by the word equations: bromine solution + sodium sulphite solution > hydrobromic acid solution + sodium sulphate solution and odine solution + sodium sulphite solution > hydroiodic acid solution + sodium sulphate solution Since hydrobromic acid solution and hydroiodic acid solution are both colorless, bromine, iodine, and chlorine solutions should all lose their color after reacting with sodium sulphite solution. However, sulphur, having very different chemical properties to chlorine, bromine, and iodine, does not react with sodium sulphite solutions at all. Materials and apparatus The materials and apparatus include: * Bromine water * Chlorine water * Hydrochloric acid solution * Iodine solution * Sodium sulphite solution Sulphur powder * 1 ? Forceps * 1 ? Protective gloves * 1 ? Safety spectacles * 1 ? Test tube brush * 1 ? Test tube rack * 3 ? Calcium granules * 3 ? Copper turnings * 3 ? Magnesium ribbon * 7 ? Test tubes Variables Variable Type| Variable| Method of Control| Independent| Element added| Add different elements to solutions| | Mass of element added| Weigh the element samples| Dependent| Vigor of reaction| Observe by sight| | Color of resulting substance| Observe by sight| | Sounds produced| Observe by hearing| | Temperature change of substance| Observe by tactile sense| | Odors produced| Observe by olfactory sense|
Controlled| Volume of solutions added| Measure the volume of solution| | Solutions added to test tubes| Add identical solutions to elements| | Molarity of solutions added| Add identical solutions to elements| Table 1: Variables involved in the experiment. Procedure Part B. 1. Label three test tubes in a rack ‘1’, ‘2’, and ‘3’ respectively. 2. Fill each tube with dilute hydrochloric acid to a depth of about 3 cm 3. Using a pair of forceps, add 2 or 3 calcium granules to test tube ‘1’ 4. Add a magnesium ribbon of 1 cm long to test tube ‘2’. 5. Put 2 or 3 copper turnings into test tube ‘3’.
Part C. 1. Label four test tubes ‘1’, ‘2’, ‘3’, and ‘4’ respectively. 2. Fill test tube ‘1’ to a depth of 2 cm. 3. Fill test tube ‘2’ with bromine water to a depth of 2 cm. 4. Fill test tube ‘3’ with iodine solution to a depth of 2 cm. 5. Fill test tube ‘4’ with 2 spatula measures of Sulphur powder. 6. Add about 2 cm3 of sodium sulphite solution to each of the four test tubes. Shake the tubes gently after each addition. Observations Three trials of the experiment was conducted. The observations of all three trials of the experiment are summarized in the table below: Part B|
Element added to hydrochloric acid solution| Observations| Calcium| Initially, calcium was in the form of irregular solid granules. Calcium had a grayish white color. When added to a hydrochloric acid solution, the calcium granule sinks to the bottom. Small, colorless gas bubbles evolve at a moderate rate, floating to the top of the solution and popping. Parts of the granule near the surface fell off. Precipitation in the form of white powder evolved and sunk to the bottom. The evolution of colorless gas bubbles became progressively vigorous and the bubbles became larger.
The bubbles floated to the top of the solution and merged to form large bubbles before popping. A sizzling sound was produced. The solutions heated up vigorously. The granule dissolved. The granule floated to the top of the solution while the reaction continued. White smoke was produced and rose from the solution. An odor resembling ash was produced. The evolution of colorless gas bubbles became very vigorous. The granule disappeared. The fallen off parts of the granule evolved colorless gas bubbles slowly, rising to the top of the solution and popping.
White precipitation developed slowly, sinking to the bottom of the solution. The fallen parts of the granule dissolved and disappeared. | Magnesium| Initially magnesium was in the form of a silvery, thin strip with parts of its surface covered with black. When added to hydrochloric acid solution, the magnesium strip sunk to the bottom. The magnesium quickly floated back up to the top of the solution. Small colorless gas bubbles rose quickly from the magnesium. The bubbles reached the top of the solution, merged into larger bubbles, then popped.
Precipitation in the form of a white powder evolved from the magnesium strip. The precipitation sunk partially before sticking to the side of the test tube. The magnesium strip dissolved, revealing a very shiny, silvery color. The colorless gas bubbles were evolved quicker and were larger. A sizzling sound was produced. The precipitate evolved more rapidly. White smoke evolved from the magnesium and rose above the solution. An odor resembling rotten eggs was produced. Heat was produced from the solution. The magnesium dissolved and disappeared. | Copper| Initially, copper was in the form of shiny orange, red chips.
When added to hydrochloric acid solution, the copper sunk to the bottom of the solution, not reacting at all. | Part C| Element added to sodium sulphite solution| Observations| Chlorine| Initially, chlorine was in the form of a colorless solution. When sodium sulphite solution was added to chorine solution, ripples bounced back and forth in the resulting solution. | Bromine| Initially, bromine was in the form of an orange yellow solution. When sodium sulphite solution was added to bromine solution, ripples bounced back and forth in the resulting solution. The resulting solution changed from an orange yellow color to colorless. Iodine| Initially, iodine was in the form of a red brown solution. When sodium sulphite solution was added to iodine solution, ripples bounced back and forth in the resulting solution. The resulting solution changed from a red brown color to colorless. | Sulphur| Initially, sulphur was in the form of a yellow powder. When sodium sulphite solution was added to sulphur, some of the sulphur powder floated to the top of the solution while the others remained at the bottom of the solution. | Table 2: The observations of the experiment are summarized in this table.
The observations noted are identical of all three trials. All observations were true in all three trials and no observation in any trial was excluded. Precautions * Acids should be handled with care. * Eye protection should be worn. * Part of the experiment should be carried out in a fume cupboard. * Aqueous solutions of chlorine, bromine, iodine readily liberate poisonous vapors and gases. * Calcium should not be touched by bare hands. It may cause burns. * Calcium granules and magnesium ribbons should be used instead of metal powder, otherwise the reactions may be too vigorous. Discussion
This experiment was conducted with three trials, each time with virtually identical observations. This shows that the experiment has a high precision and small random errors. However, errors do exist in the experiment. Firstly, chlorine solution should theoretically be pale green, changing to colorless only after its reaction with sodium sulphite solution. However, the chlorine water solution used was very pale, showing virtually no change in color after the reaction. This is an error in the experiment itself, always biased towards one side, and cannot be cancelled out by conducting multiple trials.
This is a systematic error. This error can be reduced by using a more concentrated chlorine solution. Secondly, impurities in the element samples were obviously visible, such as black parts in magnesium samples. This affects the reaction and affects all observations of the experiment such as showing decreased vigor in experiments. The impurities reduce the amount of element reacting, so is biased towards less of the intended reaction and so cannot be cancelled out by conducting many trials. This is a systematic error. This error can be reduced by obtaining more pure samples of the required elements for the experiment.
Thirdly, the mass of the reactant elements, an independent variable, was not measured. This destroys the ability to compensate the vigor of reactions by knowledge of the reactant elements’ mass. The mass of element samples are uncertain and can be biased towards either sides of vigor, able to be cancelled out by conducting many trials. This is a random error. This error can be reduced by measuring the mass of reactant elements with an electronic balance. Fourthly, the volumes of the solutions added, a controlled variable, was not measured. This leads to trials under different conditions and makes results inaccurate.
The volume of solutions added were not measured and is uncertain. This error can be biased towards either sides of the vigor of the reaction, able to be cancelled out by conducting many trials. This is a random error. This error can be reduced by measuring the volume of solutions before their addition. Conclusion This experiment aims to experimentally investigate which elements show similar chemical properties. The results of the experiment have been mainly consistent with theoretical results and show high precision. However, errors still affect this experiment.

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