ireland3e_lecture_ch03

ireland3e_lecture_ch03 - 8/18/2011 Chapter 3 Everyday...

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8/18/2011 1 Chapter 3 Everyday Chemistry of Life Our Universe is Made of Chemicals The entire science of biology rests on a foundation of chemistry and the exact interactions among chemicals determine everything from birth to death We use chemistry in our daily lives without realizing it cooking cleaning bathing watering our plants
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8/18/2011 2 Life Has a Unique Chemistry Oxygen, carbon, hydrogen, and nitrogen make up the majority of living things Humans also contain small quantities of calcium, phosphorus and sulfur, sodium, chlorine, and magnesium and trace elements such as iron, iodine, and selenium Atomic Structure is the Foundation of Life Elements are made of atoms Each atom is the smallest possible sample of a particular element Atoms include a central nucleus with a cloud of electrons orbiting through electrical attraction to the positive protons of the nucleus Atoms react with other elements to form compounds and molecules
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8/18/2011 3 Isotopes Many elements have isotopes, with the same number of protons but a different number of neutrons All isotopes of a particular element are chemically identical to the element but have different masses Atomic number - number of protons in the nucleus Atomic mass number of protons and neutrons in the nucleus The Periodic Table Chemistry encompasses a vast amount of information that can be useful only if it is organized The periodic table organizes all elements in a logical pattern, according to atomic number The table also reveals an element’s reactivity – its ability to bond with other elements Elements in a particular column have the same number of valence electrons, and thus similar reactive properties
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8/18/2011 4 The Periodic Table Orbitals Valence shell outermost energy level of e - , where atoms bond together Noble gases -- Atoms with eight electrons in the valence shell will usually not bond Atoms without a “filled” valence shell adhere to one another by sharing or moving electrons An atom with one to three electrons in its valence shell can lose electrons forming a positive ion An atom with five to seven electrons in its outer shell tends to grab electrons to fill forming a negative ion
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8/18/2011 5 Chemistry is a Story of Bonding Life is made of atoms, but atoms are only the building blocks of molecules and chemical compounds A molecule is a chemical unit formed from two or more atoms for example, H 2 is a molecule of hydrogen a compound is a molecule with unlike atoms CO 2 , carbon dioxide, is both a molecule and a compound Bonds between atoms determine how chemical compounds form, fall apart, and re-form Atoms can bond in three common ways ionic bonds covalent bonds hydrogen bonds
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8/18/2011 6 Ionic Bonds Ionic bonds hold ions in a compound they are based on the strong attraction between positive and negative ions Many ions in the human body, including calcium (Ca 2+ ), sodium (Na + ), potassium (K + ), hydrogen (H + ), phosphate (PO
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ireland3e_lecture_ch03 - 8/18/2011 Chapter 3 Everyday...

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