Class Chapter 2 Lecture Presentation

Class Chapter 2 Lecture Presentation - Biology Eighth...

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Unformatted text preview: Biology Eighth Edition Neil Campbell and Jane Reece Chapter 2 The Chemical Context of Life Learning Objectives: 1. To identify the four major elements that make up 96% of living matter for humans. 2. To define what matter is and distinguish between the following sets of terms: element and compound; neutron, electron and proton, atomic number and mass number, and atomic mass and mass number. 3. To distinguish between and discuss the biological importance of the following: polar covalent bonds, nonpolar covalent bonds, ionic bonds, hydrogen bonds, and van der Waals interactions. Overview: A Chemical Connection to Biology Biology is a multidisciplinary science. Living organisms are subject to the basic laws of physics and chemistry. One example is the use of formic acid by ants to maintain devils gardens, stands of Duroia hirsuta trees. The ants live in the hollow stems of the trees. They prevent other plant species from growing in the garden by injecting intruders with a poisonous chemical. In this way, the ants create space for the Duroia trees that serve as their home. Concept 2.1: Matter consists of chemical elements in pure form and in combinations called compounds Organisms are composed of matter, which is anything that takes up space and has mass. Matter exists in many diverse forms. Rocks, metals, oils, gases and humans are just a few examples of what seems an endless assortment of matter. Elements and Compounds Matter is made up of elements. An element is a substance that cannot be broken down to other substances by chemical reactions. Chemists recognize 92 elements occurring in nature. Each element has a symbol, usually the first letter or two of its name. A compound is a substance consisting of two or more elements in a fixed ratio. Table salt, for example, is a compound composed of two elements, they are sodium (Na) and chlorine (Cl) in a 1:1 ratio. Sodium Chlorine Sodium chloride Pure sodium is a metal Pure chlorine is a poisonous gas Table salt The emergent properties of a compound A compound has characteristics different from those of its individual elements. Essential Elements of Life About 25 of the 92 elements in the periodic table are essential to life. Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) make up 96% of living matter in humans. Most of the remaining 4% of living matter consists of calcium (Ca), phosphorus (P), potassium (K), and sulfur (S). Trace elements are those required by an organism in only minute quantities. Some trace elements, such as iron (Fe), are needed by all forms of life, while others are required by only certain species. Concept 2.2: An elements properties depend on the structure of its atoms Each element consists of unique atoms that are different from the atoms of other elements....
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Class Chapter 2 Lecture Presentation - Biology Eighth...

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