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Atoms, Molecules, and Water

Atoms, Molecules, and Water - ATOMS MOLECULES AND...

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ATOMS, MOLECULES, AND WATER (Chapter 2) I. Atomic Structure What is an atomic mass unit (amu) ? What is Dalton ? -Atomic mass unit also known as Dalton. One amu is equal to the approximate mass of a single proton or a single neutron. Adding a number of neutrons and protons. How do electrons , neutrons , and protons compare in mass, charge and atomic location? Do all atoms of the same element have the same atomic mass ? The same atomic number ? Why? What is the standard notation used to express these values? II. Isotopes and use of tracers in biology Why can Isotopes of the same element generally substitute for each other? -Because they have the same number of electrons, all isotopes of a given element have essentially the same chemical characteristics. Why are radioactive tracers extraordinary useful to biologists? - For this reason, radioisotopes such as 3 H (tritum), 14 C, and 32 P are extremely valuable research tools used in areas such as dating fossils, tracing biochemical pathways, determining the sequence of genetic information in DNA, and understanding sugar transport in plants. In medicine: the location and/or metabolism of a substance such as hormone or drug can be followed in ht ebody by labeling the substance with a radioisotope such as carbon-14 or tritum. How does the technique of autoradiography work? -Radiation causes the appearance of dark silver grains in photographic film. Because the different isotopes of a given element have the same chemical characteristics, they are essentially interchangeable in molecules. Molecules containing radioisotopes are usually metabolized and/or localized in the organism in a similar way to their nonradioactive counterparts, and they can be substituted. III. Ions How can an atom ionize, becoming a cation? An anion?
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