chapter2 - Chapter 2: You must understand chemistry to...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
BIOL 1020 - CHAPTER 2 LECTURE NOTES Chapter 2: You must understand chemistry to understand life (and to pass this course)! Overview: In many ways, life can be viewed as a complicated chemical reaction. Modern models of how life works at all levels typically have at least some aspect of chemistry as a major component or underpinning. I. Elements and Atoms A. elements – substances that cannot be further broken down into other substances (at least by ordinary chemical reactions) 1. every element has a chemical symbol (H for hydrogen, O for oxygen, etc.); this is most familiar from the periodic table 2. there are 92 naturally occurring elements , from hydrogen up to uranium 4 elements (oxygen, carbon, hydrogen, and nitrogen = O, C, H, N ) make about 96% of the mass of most living things 8 others are consistently present in small amounts in living things (Ca, P, K, S, Na, Mg, Cl, Fe) several others are typically found only in trace amounts ( trace elements ); these tend to vary considerably in amount and even presence depending on the type of organism B. an atom is the smallest unit of an element that still retains the properties of that element C. atoms consist of subatomic particles 1. electron - contributes no significant mass to the atom, but carries a (-1) electrical charge 2. proton - contributes a mass of approximately 1 mass unit, and carries a (+1) electrical charge 3. neutron - contributes a mass of approximately 1 mass unit, and carries no net electrical charge 4. protons and neutrons are found in the nucleus (center) of an atom 5. elements differ from each other because they contain different numbers of protons (all hydrogen atoms contain 1 proton, all carbon atoms contain 6 protons, all oxygen atoms contain 8 protons, etc.) atomic number = number of protons in the nucleus the periodic table has elements arranged largely according to atomic number 6. protons + neutrons determine atomic mass 1 of 6
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
BIOL 1020 - CHAPTER 2 LECTURE NOTES each contribute ~1 atomic mass unit (amu, or Dalton) atoms that have the same number of protons but have different numbers of neutrons (therefore different masses) are referred to as isotopes D. atomic nuclei can undergo changes (decay) 1. some elements are more stable than others 2. some isotopes are more stable than others (most unstable = radioisotopes ) 3. decay rates are statistical averages, and are used for measuring time passage in many areas of science (carbon dating, etc.) 4. the radiation emitted upon decay (alpha, beta, and/or gamma) can be used as a tool for experiments; can also be used medically; has other uses and dangers (nuclear power, nuclear bombs, radiation poisoning, etc.) 5. radiation can cause mutations in DNA, can interfere with cell division
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

chapter2 - Chapter 2: You must understand chemistry to...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online