biology chapter 2 and 3

biology chapter 2 and 3 - Chapter 2: The Chemical Context...

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Chapter 2: The Chemical Context of Life Review 2.1 Matter Consists of Chemical Elements in Pure Form and in Combinations Called Compounds -matter: anything that takes up space and has mass -element: a substance that cannot be broken down to other substances by chemical reactions -compound: a substance consisting of 2 or more different elements combined in a fixed ratio (ie: Na-Cl+) -trace elements: required by an organism in only minute quantities (ie: Fe) 2.2 An Element’s Properties Depend on the Structure of its Atoms -atom: smallest unit of matter that still retains the properties of an element -atomic nucleus: dense core at the center of an atom which have tightly packed protons and neutrons -the dalton: atomic mass unit -properties -atomic number: number of protons unique to that element -mass number: sum of protons and neutrons -atomic mass: an approximation of the total mass of an atom -Isotopes: different atomic forms of the element with the same atomic number but a different mass number -energy: capacity to cause change -potential energy: energy that matter possesses because of its location or structure -electron shells: a characteristic average distance and energy level -orbital: 3D space where an election is found 90% of the time 2.3 The Formation and Function of Molecules Depend on Chemical Bonding Between Atoms -covalent bond: sharing of a pair of valence electrons by two atoms -single bond: a pair of shared elections -structural formula: represents both atoms and bonding -molecular formula: indicating that the molecule consists of 2 atoms of
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This note was uploaded on 03/03/2010 for the course BIOG 1101 taught by Professor N/a during the Fall '10 term at Cornell.

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biology chapter 2 and 3 - Chapter 2: The Chemical Context...

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