01:119:116 Lecture Notes - Lecture 13: Electron Shell, Covalent Bond, Atomic Nucleus
3 Dec 2017
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Topic 2- 5/31/17: methods of investigating biology, the scientific process- Hypothesis- testable explanation for observations based on available data- e. g expired milk will make you sick. Law- statement of what always occurs under certain circumstances: observation-> background->hypothesis, which leads to prediction-> experiments/ Observations-> evaluate (if incorrect predictions, revise hypothesis- revise and repeat)- > repeat and verify- ask a new question. Ii: properties of atoms depend on structure- 25 of the 92 elements essential to life. Four make up 96% of living matter- c h o n- other 4% are calcium, phosphorus, Each element consists of unique atoms- atoms are composed of 3 subatomic particles- Proton(+), neutron(neutral), electron(-)- electrons form a negative cloud around the the nucleus while protons and neutrons are in the atomic nucleus. Atomic # = # of protons in atom. Valence shell- outermost shell- where bonds between electrons form. Isotopes= two atoms of an element that differ in the number of neutrons i. e c12 ,c13.
