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WA_2-16 Biology - La Rosa1 Melissa La Rosa Dr Martinez...

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La Rosa1 Melissa La Rosa Dr. Martinez Intro to Biology 2/7/12 Writing Assignment # 2 1. What is the basic structure of an atom? How are subatomic particles typically arranged? The rest of the atom consists of a positively charged nucleus of protons and neutrons that are surrounded by a cloud of negatively charged electrons. The nucleus is the center of the atom. An atom is an extremely small particle of matter that retains its identity during chemical reactions. These subatomic particles are divided into two main groups, the leptons and the hadrons. The best known lepton ("light" particle) is the electron. In order to account for the emission of electrons from the nucleus, the neutrino, an essentially massless neutral particle was postulated. The muon and the tau, both much more massive than the electron, comprise the rest of the lepton family. The hadrons are divided into two groups, the mesons and the baryons. Protons and neutrons are baryons. Mesons and baryons are made of smaller particles called quarks. There are six different quarks: up, down, charmed, strange, top, and bottom. While these are cool names, they convey nothing about the distinct properties of the quark. Each quark comes in three different colors: red blue and green. 2. Why do atoms interact with other atoms to form compounds? What attracts one atom to another? They want to share electrons, especially those atoms in certain groups, atoms that have 1 electron in their outer shell or are missing one electron to make the shell complete. So these atoms share their electrons with other atoms that also need to share electrons. It can be said that the energy state of the atom while it is sharing the electron under the proper conditions is more stable. And that is why certain atoms prefer to share their electrons with certain other atoms, for example H and O to form water, but since H only has one electron to give and O requires 2 electrons to fill its outer shell, they combine into H2O. The force
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La Rosa2 that attracts electrons from one atom to another is nuclear force. It is the attraction between protons and electrons. 3. How do ionic bonds, covalent bonds and polar bonds differ? There are two types of atomic bonds - ionic bonds and covalent bonds. They differ in their structure and properties. Covalent bonds consist of pairs of electrons shared by two atoms, and bind the atoms in a fixed orientation. Relatively high energies are required to break them (50 - 200 kcal/mol). Whether two atoms can form a covalent bond depends upon their electro negativity i.e. the power of an atom in a molecule to attract electrons to itself. If two atoms differ considerably in their electro negativity - as sodium and chloride do - then one of the atoms will lose its electron to the other atom. This results in a
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