Breakdown of Chemistry Essay

1246 WordsAug 28, 20135 Pages
CHEMISTRY Chapter 2 (4 hrs.) I. Like life, matter has levels of organization: A. Organisms> systems> organs> tissues> cells B. Matter > compounds> elements> atoms All matter is made up of some combination of the 109-odd elements, which are the basic units. Elements are identified by their sub-atomic particle makeup (the arrangement of subatomic particles). Elements are grouped according to characteristics into horizontal groups and vertical periods in the periodic chart, devised by Dimetri Mendelev. The atom = the smallest particle of matter indivisible by chemical means A. Parts of the atom (subatomic particles) 1. Nucleus – central portion, composed of: a. Neutron – an uncharged particle with an atomic weight of one. The atomic weight of the atom equals the weight/number of protons plus the weight/number of neutrons. b. Proton – a positively charged particle with an atomic weight of one. The atomic number of an atom equals the number of protons. 2. Orbitals – a cloudlike shell around the nucleus, composed only of electrons, weightless particles with a negative charge. B. Elements are any substance composed of only one type of atom . There are 92 natural plus 20 manmade. C. The periodic chart and Bohr diagrams are ways man organizes the elements. The Behavior of atoms is governed by certain Energetic Tendencies A. Valence = A tendency of an atom to either pick up or lose electrons (expressed as either a positive or negative number). B. Electrons tend to pair, according to the octet rule C. Inner orbitals fill first – K holds 2 electrons, L holds 8 , M holds 8, N holds 18, last always holds 8. D. Charges tend to balance each other ( positive seeks negative) E.

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