surrounding. To see them in an unstained state and also to observe their motility‚ a hanging-drop or a wet mount technique is used. A wet mount is the technique of placing small amounts of specimen in a droplet of water for viewing with the compound microscope. Motility is an inheritable phenotype and is critical for identification and classification of bacteria. The technique is done by applying petroleum jelly to all sides of a cover glass. Add a water droplet and specimen using an aseptic loop onto
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MICROBIAL SURVEY‚ SMEAR PREPARATION‚ AND SIMPLE STAIN Instructional Objectives 1. Define Roccal = green‚ liquid disinfectant. Pathogen = an agent which causes disease. Wet Mount Slide = a microscope slide of a liquid specimen covered with a cover glass. Yeast = a single celled fungi. Budding = a true characteristic method of asexual reproduction among yeasts where budding of a new cell from a parent cell can be observed. Mold = multicellular masses of filamentous fungal growth. Hyphae
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1. Determine the Number of valence electrons in the Lewis Structure: One of the easiest ways to start drawing a Lewis Structure is to make a list of each atom in the structure and next to each atom record how many valence electrons it has and how many it needs to fill its valence shell. In covalent bonding the valence electrons in the molecule come from the valence electrons in the atoms that formed the bond. a. The number of valence electrons in any main group atom is equal to its
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Onion Distilled Water Apparatus: Microscope Microscope slides & cover slips Tile Knife Tweezers Pasteur Pipettes Assignment: I was given the onion once it had been chopped up on the tile‚ ready for me to peel back the skin I required using the tweezers. I then placed piece of onionskin onto the microscope slide‚ making sure there were no folds or creases‚ and put a drop of iodine onto the slide as well‚ to view through the microscope. On my first try the onion folded so I
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bonds are formed when atoms share electrons‚ one from each atom in a single bond‚ to form electron pairs‚ usually making their outermost shells up to eight electrons by this means. This would make them more stable‚ less reactive and an electronic structure like a noble gas. They are most frequently formed between pairs of non-metallic elements. Non-metallic elements usually have from four to eight electrons in their outermost shells‚ the so-called valency electrons‚ which are used for chemical bonding
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was one experiment conducted by Hertz‚ the photoelectric effect‚ which could not be explained by considering light to be a wave. Hertz observed that when certain metals are illuminated by light or other electromagnetic radiation‚ they lose electrons. Suppose we set up an electric circuit. In this circuit the negative terminal of a battery has been connected to a piece of sodium metal. The positive terminal of the battery is connected through a meter that measures electric current‚ and to
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Lewis Structure Review How To Write Lewis Structures 1. Determine the total number of valence electrons from all of the atoms in the molecule or ion. • Add one electron for each unit of negative charge. • Subtract one electron for each positive charge. 2. Write the correct skeletal structure. • For molecules of the formula ABn‚ place the least electronegative element in the center‚ and the more electronegative elements in the terminal positions. • H is always a terminal atom‚ and NEVER a central
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to light reflection. 2. Electron Double Slit Experiment a. Electrons are fired (possibly one at a time) toward a screen with two slits and each electron that passes through leaves a dot on a film plate. The dots accumulate on specific places‚ as shown in the diagram below‚ separated by b lank zones. Therefore‚ there is a certain probability that an electron may land on C‚ E‚ G… and zero probability that it may go to D‚ F… b. The probability that an electron may land on some point on
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Neutron # # of Electrons Mass Number Charge Ar 19 31 17 18 35 20 18 3+ 40 3. In your own words‚ explain Thomson’s and Rutherford’s contribution to the atomic theory. Give sketches to substantiate your answer. 4. Explain how Bohr contributed in defining the structure of the atom. 5. Magnetic resonance imaging (MRI) is a powerful diagnostic tool used in medicine. The imagers used in hospitals operate at a frequency of 400 MHz (1 MHz = 106 Hz). Calculate: (a) The wavelength
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between electrons and nuclei‚ or as the result of a dipole attraction. The strength of chemical bonds varies considerably; there are "strong bonds" such as covalent or ionic bonds and "weak bonds" such as dipole–dipole interactions‚ the London dispersion force and hydrogen bonding. Since opposite charges attract via a simple electromagnetic force‚ the negatively charged electrons that are orbiting the nucleus and the positively charged protons in the nucleus attract each other. Also‚ an electron positioned
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