group two have‚ group two has 2 valence electrons. When group two elements become ions what is their charge‚ their charge is +2. What are the group 17 elements called‚ they are called the Halogens. List the group 17 elements‚ Fluorine‚ Chlorine‚ Bromine‚ Iodine‚ and Astatine. How many valence
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____ 2. 2s22p6 B. Which has the lowest first ionization energy? ____ 3. D = 2s22p5 C. Which is a noble gas? 10. Convert 4.3 kilograms to centigrams using dimensional analysis. 11. Consider the elements neon‚ bromine‚ and phosphorus. Which has five electrons in its 4p sublevel? 12. Write the formula obtained when this atoms loses or gains valence electrons and becomes an ion. Tell whether it is a cation or an anion. Be 13
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Who discovered the element? Selenium was discovered by Jons Jacob Berzelius in 1817. How was the element discovered? Selenium was discovered by Jons Jakob Berzelius in 1817. In 1817‚ he was studying the chemicals used in making sulfuric acid‚ but they got selenium from a red-brown sediment which collected at the bottom of the chambers in the particular plant. At first he thought it was the element tellurium and tellurium is a rare element‚ so he brought it back to his laboratory. After studying
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CHEM3412 Synthesis of a Porphyrin Porphyrins are hetereonuclear‚ macrocyclic compounds that play an important role in living organisms. Examples include the non-protein heme portion of hemoglobin in animals whereby the lone pairs on nitrogen can bind to the oxygen-carrying iron. In plants‚ chlorophyll uses the vast conjugation to allow absorption of light for photosynthesis. The characteristic colors of porphyrins is also due to the conjugation. An examination of the porphyrin structure
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(100) Convert each of the following. (Chapter 3) a. 4.72 g to mgHint b. 2.7 × 103 cm/s to km/hHint c. 4.4 mm to dmHint (101) How many protons‚ electrons‚ and neutrons are in each isotope? (Chapter 4) a. zirconium-90 b. palladium-108 c. bromine-81 d. antimony-123 (102) Write the complete electron configuration for each atom. (Chapter 5) a. fluorine b. lithium c. rubidium (103) Why do the elements magnesium and barium have similar chemical and physical properties? (Chapter 6) (104)
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electron structure/ are the same element/ have the same atomic number/ are isotopes. (Do not accept Y and Z have same no. of e－ in outermost shell) 1 1994 - 7(b) Marking Scheme (i) Bromine exists as simple molecules with weak intermolecular attraction/ weak van der Waal’s force. ∴ it has low b.p. (Do not accept bromine has weak covalent bond.) In Lead(II) bromide‚ the attraction between ions is strong/ ionic bond/PbBr2 has strong electrostatic attraction. ∴ it has higher a m.p. (Do NOT accept lead(II)
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1) tetrarsenic decoxide 2) bromine trioxide 3) boron nitride 4) dinitrogen trioxide 5) nitrogen triiodide 6) sulfur hexafluoride 7) xenon tetrafluoride 8) phosphorous trichloride 9) carbon monoxide 10) phosphorous pentachloride 11) diphosphorous pentoxide 12) disulfur dichloride 13)
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Experiment 1: TLC Analysis of Analgesic Drugs 1/23/2011 Purpose: The goal of this experiment is to test our knowledge and understanding of TLC analysis by having us do a TLC analysis of analgesics to figure out their main chemical components. Calculations: 1.) Rf = Distance spot traveled/ distance solvent traveled Results: Table 1: TLC Analysis Analgesic Drugs | Rf Value | Acetaminophen | 0.323 | Aspirin | 0.597 | Caffeine | 0.081 | Unknown 154 (Plate 1) | 0.081‚ 0.306‚ 0.597
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absorption frequencies in the spectrum‚ and associate each with a specific bond (e.g. O–H‚ C=O). Keep in mind that there are usually only one or two key bands in each spectrum‚ although in some cases you might observe up to three. Do not label the alkane C–H stretch‚ since these bands are present in most organic compounds. 2. Assign a letter from the structures given (A – J). There is only one structure per spectrum. 3. Identify the main functional group present in the structure (i.e. ketone‚ alcohol
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column are more similar than elements in the same horizontal row. Seventy five percent of the table is made up of metals‚ and a couple of the columns on the right of the table have gases. There are only two elements that are liquids- mercury and bromine. Column 1 contains the alkali metals‚ which suddenly combust when exposed to air or water. Columns 3-12 are the transition metals‚ which contain heavier atoms‚ which are more flexible in how they organize their electrons. Column 17 is made up of the
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