Chapter 2 The Chemical Context of Life

Chapter 2 The Chemical Context of Life - Chapter 2: The...

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Chapter 2: The Chemical Context of Life Elements and Compounds - Organisms are composed of matter which is anything that takes up space and has mass. - Matter is made up of elements , a substance that cannot be broken down into any other substance by chemical reactions. Purest form of matter. - A compound is a substance consisting of two or more different elements combined in a fix ratio. Ex: NaCl (sodium chloride) Essential Elements of Life - Four elements make up 96% of living matter. They are: Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N). - The remaining 4% of an organisms weight consists of: Phosphorus (P), Calcium (Ca), Sulfur (S), Potassium (K) and a few other elements (Trace elements) - Trace elements are those required by an organism in only minute quantities. - For example iodine, is a trace element (daily intake of 0.15 mg) used by the thyroid gland to produce hormones ( , T3 T4 ) . A deficiency of iodine in the diet can cause the thyroid to grow to an abnormal size, a condition called a goiter. Subatomic Particles - An atom is the smallest unit of matter that retains the properties of an element. - Atoms are composed of smaller parts called subatomic particles:
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Protons (positive charge) found in the nucleus. Mass of 1 amu (atomic mass unit). The number of protons identify the element. Neutrons (neutral) found in the nucleus. Mass is about 1 amu Electrons (negative charge) surround the atomic nucleus. Mass is so small it is irrelevant to the mass of the entire atom. - Number of protons is the same as the number of electrons in an electrically neutral atom Atomic Number and Atomic Mass - Atomic number of an element is the number of protons found in the nucleus. - Atomic mass is the sum of protons and neutrons in the nucleus. -
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Chapter 2 The Chemical Context of Life - Chapter 2: The...

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