Chemistry160-page2 - atom Particles in the Nucleus Proton...

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Chemistry Concepts - 2 The Arrangement and Properties of Atoms Atoms are composed of hundreds of smaller subatomic particles. Fortunately, to understand Biology 101, we need only look at three of these basic particles, which are located in two regions of the atom: the nucleus and the surrounding electron orbitals. The "force" that holds these particles "together" forming the atom is an electrical charge (positive and negative) between subatomic particles. The nucleus of an atom contains two sub-atomic particles: protons and neutrons. A third type of particle, electrons, are found in orbitals in motion surrounding the nucleus of the atom. Let's look a little at the structure of the atom. The Nucleus • The central portion of the atom • Contains two types of subatomic particles • Contains the bulk of the atom's mass, but very little of the space of an
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Unformatted text preview: atom Particles in the Nucleus Proton • Positively charged particle ( + ) • Number of protons in the nucleus for a particular element is always constant (and fixed) • The number of protons ranges from 1 ---> 108 from which the atomic number is assigned. • An element is defined by its number of protons. • Each proton has a relative mass of "1" (For biology purposes, this is fine. It's actually 1 dalton, which is a relative measure of the mass of the hydrogen atom). Neutron • No electrical charge • Mass of "1" (just a tiny bit heavier than the proton; not enough for us to be concerned about). • About the same number of neutrons as protons/atom, although the ratio changes with larger atoms. .. • The number of neutrons plus the number of protons gives the atomic mass (or atomic weight) of an atom....
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This note was uploaded on 12/29/2011 for the course BIO 151 taught by Professor Edwards during the Spring '10 term at SUNY Stony Brook.

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