1.2_Basic_biochemistry_I - Now lets look at some basic...

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Now lets look at some basic chemistry. 1
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Make sure to carefully study chapter 2 if these concepts are new to you. 2
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Let’s start with some definitions. The definitions on the slide are provided by the textbook; however, I ‘d like to add some simple reminders. First, we are going to use a very basic and simple model to understand what an atom is. This model is referred to as the Rutherford-Bohr model named after the two researchers who contributed aspects of the model. The basic idea of this model is familiar to us- the notion that the dense inner nucleus of an atom is made of two particle types (positively charged protons and neutral neutrons) and that much smaller negatively charged particles orbit around the nucleus. Elements are defined by the number of protons that they have. For example, the element carbon has six protons; no other element has six protons in the nucleus. Atoms of the same element may have a different number of neutrons though and we call these isotopes of the element. When atoms bond together by sharing electrons, they are called molecules. Often atoms are associated with one another in other ways and so we have a more general term for this combined substance compounds. Note that compounds will have a consistent ratio of the different elements though. 3
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So, to follow up on the idea of an element being defined by the number of protons, we see that carbon always has 6. It can vary in the number of neutrons, for example, the Carbon-13 isotope has 7 neutrons instead of the typical 6 so it would be considered a heavy isotope of carbon. Carbon 13 is stable, meaning that it stays as Carbon 13 whereas another isotope of Carbon, Carbon-14, does not remain as it is and will naturally break down to release radioactive particles. Given that carbon is only taken in by an organism when it is living and the carbon-14 concentration will begin to decline once an organism dies; we can use the ratio of Carbon-14 to the stable isotopes of carbon as a means of aging very old remains of wood or bone. There are many interesting research methods associated with isotope ratios. Finally, you should be familiar with the atomic mass which is a weighted average of all isotopes. For carbon, the Carbon-13 is rare enough that it hardly affects the average. The upper right illustration shows the basic model of an atom; though in this case, the electrons are shown as a cloud rather than individual orbiting particles. 4
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This is a sculpture of a Russian chemist who played an important role in modern chemistry. He’s known for a variety of discoveries; however, his work with organizing the elements into a table that reflects repeating patterns is what he is known best for. Our Periodic Table is based on his original work over a hundred years ago. Read up on
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1.2_Basic_biochemistry_I - Now lets look at some basic...

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