BIOL164Ch2NotesWin12

BIOL164Ch2NotesWin12 - Ch. 2 Chemistry Comes to Life Some...

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1 Ch. 2 – Chemistry Comes to Life • Some key themes from this chapter: – Basic chemistry helps us understand human biology Chemistry = the science of the composition and properties of matter – Carbohydrates, lipids, proteins, and nucleic acids are the major molecules of life • A.k.a. “ bio chemistry The building blocks of matter Matter = anything that takes up space and has mass (weight); i.e., substances, or the “stuff” of the universe – Matter can exist as a solid , liquid , or gas Atoms = units of matter that can’t be broken down further by ordinary chemical means – Their net charge = 0 (zero), and they’re made up of… Protons (+ charge, part of the nucleus, mass 1 amu) Neutrons (0 charge, part of the nucleus, mass 1 amu) Electrons (- charge, orbit the nucleus, mass is negligible) Atomic number = the # of protons Atomic weight (atomic mass) = the # of protons + the # of neutrons Figure 2.1
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2 The periodic table of the elements Element = a “pure” form of matter composed of atoms of all of the same type The most common elements found in humans are: C, H, O, N, P, and Ca •A few other important elements in humans (there are many more) are: Na, K, Fe, and Mg Figure 2.2 Electron shells Atoms have equal numbers of protons and electrons, so overall they are electrically neutral – Compare atoms to ions • The outermost electron shell determines an atom’s reactivity with other atoms (an atom is stable only if this shell is full) Figure 2.8
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3 Atoms combine via chemical reactions, forming chemical bonds • Chemical bonds contain energy (more on this soon…) – An input of energy is needed in order to make chemical bonds – Energy is released when chemical bonds are broken Molecule = a chemical structure consisting of atoms (of any elements) held together by covalent bonds – E.g. O 2 (oxygen gas), H 2 O (water), C 6 H 12 O 6 (glucose) Compound = a chemical substance composed of atoms of two or more different elements, regardless of bond type – E.g. NaCl (table salt), H 2 O, C 6 H 12 O 6 • Major types of bonds (see Table 2.2): –1 . Covalent bonds – the bonded atoms share electrons • These are the strongest bond type; most of the energy we get from food involves breaking covalent bonds –2 . Ionic bonds – the bonded atoms lose or gain electrons • These can be fairly strong when dry, but they dissolve in water –3 . Hydrogen bonds – polar molecules weakly interact with each other • These are weak individually, but lots of them working together can be strong overall Single covalent bonds •1 pair of electrons are shared per bond Figure 2.9a
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This note was uploaded on 03/12/2012 for the course BIOL 164 taught by Professor Tonychennault during the Winter '12 term at Clark College.

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BIOL164Ch2NotesWin12 - Ch. 2 Chemistry Comes to Life Some...

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