BIO-198 Lecture 2: Chapter 2
Nature of Atoms
Matter has mass and occupies space
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All matter is composed of atoms
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Understanding the structure of atoms if critical to understanding the
nature of biological molecules
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Atoms are composed of protons, neutrons, and electrons
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# of protons = # of electrons
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Atomic number = # of protons
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Atomic mass = protons + neutrons
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Cation: loss of electrons
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Anion: extra electrons
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Isotope: atoms of a single element that has different numbers of
neutrons
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Half-life: time it takes for one-half of the atoms in a sample to decay
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Electrons
Bohr models shows electrons in discrete orbits
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No orbital can contain more than two electrons
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Electrons have potential energy related to their position
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Further away = more energy
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During some chemical reactions, electrons can be transferred from one
atom to another
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Redox reaction
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Oxidation: loss of an electron
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Chapter 2
Friday, January 24, 2020
12:22 PM
Document Summary
Understanding the structure of atoms if critical to understanding the nature of biological molecules. Atoms are composed of protons, neutrons, and electrons. Isotope: atoms of a single element that has different numbers of neutrons. Half-life: time it takes for one-half of the atoms in a sample to decay. No orbital can contain more than two electrons. Electrons have potential energy related to their position. During some chemical reactions, electrons can be transferred from one atom to another. Periodic table displays elements according to valence electrons. # of electrons in the outermost energy level. Octet rule: atoms try to have completely full outer energy levels. Only 12 elements are found in living organisms. Carbon, hydrogen, oxygen, and nitrogen makes up 96. 3% of human body weight. Molecules: group of atoms held together in a stable association. Compounds: molecules containing more than one type of element. Ionic bonds: formed by the attraction of oppositely charged ions.
