Biol 1408 Chapter 2 (Chemistry of Life) Lecture

Biol 1408 Chapter 2 (Chemistry of Life) Lecture - 1/21/11...

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1/21/11 1 CHAPTER 2: THE CHEMISTRY OF LIFE Life depends on chemical reactions. The oxygen you are breathing is from a chemical reaction Without it we would also not have aspirins, toys, cars, computers etc. Matter The l stuff z of the universe Anything that has mass and takes up space States of matter Solid – has definite shape and volume Liquid – has definite volume, changeable shape Gas – has changeable shape and volume Chemical Composition Every solid, liquid or gas is a collection of one or more elements-forms of matter that have mass & take up space. 92 naturally occurring elements Atoms are the building blocks of elements Oxygen, Carbon, Hydrogen and Nitrogen are the most abundant atoms in humans. We also have several trace elements Other living things have a similar make-up. Non-living things vary significantly in make-up.
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1/21/11 2 Properties of Elements Each element has unique physical and chemical properties Physical properties – those detected with our senses Chemical properties – pertain to the way atoms interact with one another Structure of Atoms Atom- smallest part of element retaining properties of the element Atoms are composed of three particles: Protons (p+) are part of the atomic nucleus have a positive charge (+) the total number of protons in an atom is called the atomic number (unique for each element). Neutrons are also a part of the nucleus neutral, uncharged protons plus neutrons = atomic mass. Structure of Atoms
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1/21/11 3 Electrons (e-) move around the nucleus. negatively charged (-) their quantity is equal to that of the protons attracted to protons but repelled by other electrons. Structure of Atoms - - + - + Models of the Atom Planetary Model – electrons move around the nucleus in fixed, circular orbits Orbital Model – regions around the nucleus in which electrons are most likely to be found Describing an Atom The atomic number is the # of protons in an atom. The atomic mass number is the # of protons + neutrons in an atom These numbers give us an idea of whether and how substances will react Atomic #2; Mass #4 Atomic weight – average of the mass numbers of all isotopes
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1/21/11 4 Isotopes -- Variant Forms of Atoms Atoms with the same number of protons (e.g., carbon with 6) but a different number of neutrons (carbon can have 6, 7, or 8 neutrons) are isotopes (12C, 13C, 14C). Some radioactive isotopes are unstable and tend to decay into more stable atoms. Isotopes can be used to date rocks and fossils (carbon dating) . Decay rate is constant. Neutron number can vary Isotopes Some can be used as tracers to follow the path of an atom in a series of reactions or to diagnose disease.
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This note was uploaded on 01/06/2012 for the course BIOL 1408 taught by Professor Markgarcia during the Fall '11 term at Collins.

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Biol 1408 Chapter 2 (Chemistry of Life) Lecture - 1/21/11...

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