Biol_1001_Chap2

Biol_1001_Chap2 - 1 NOTES FOR BIOLOGY 1001 SECTIONS 003 and...

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NOTES FOR BIOLOGY 1001 SECTIONS 003 and 007 Fall 2011 DR. STEVEN POMARICO, INSTRUCTOR CHAPTER 2 ATOMS, MOLECULES AND LIFE >>>>>>>An understanding of chemistry is important because the interaction between atoms is one of the lowest levels of biological organization. >>>>>The basic unit of all forms of matter is the atom --- atom is the smallest unit of matter that retains the physical and chemical properties of the element. >>>>>>>Atoms are made up of subatomic particles. The 3 most stable subatomic particles are: neutrons, protons, and electrons (see fig 2.1) --- Protons are positively charged particles found at the core, or nucleus , of the atom . --- Neutrons are uncharged particles found at the core, or nucleus , of the atom . --- Electrons are light, negatively charged particles that orbit around the nucleus in electron shells 1
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NEUTRON PROTON ELECTRON charge uncharged +1 charge -1 charge location at the core of the atom known as the nucleus at the core of the atom known as the nucleus orbiting around the nucleus in electron shells >>>>A collection of atoms of the same type form an element --- element is a substance that can’t be broken down into other substances by chemical reactions. (see table 2-1) -elements are composed of atoms (Key Elements: hydrogen, oxygen, carbon, nitrogen) >>>The Atomic Nucleus --- atomic number is the number of protons in an atom of a particular element (see table 2-1) -The atomic number is constant for a given element Atomic Number: - Oxygen : 8 protons + 8 neutrons = 16 atomic mass - Carbon: 6 + 6 = 12 atomic mass - Hydrogen: 1 = 1 atomic mass - Nitrogen: 7 = 14 atomic mass The atomic weight of an element is the number of protons plus the number of neutrons The atoms of a particular element may have different numbers of neutrons This difference results in isotopes --- Isotopes are atoms of the same element which have different atomic weights If the valence shell isn't full, it will be reactive. If full, it won't be reactive. If it's not full, atoms will react in a goal to make it full. Hydrogen's Valence Shell has one electron inside, but has room for two. >>>The Electron Orbitals 2
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--- Electron orbitals are the three-dimensional space around the nucleus of an atom where an electron will be found 90% of the time. (See fig 2.2) ---The electron orbitals of an atom are arranged in electron shells based on their energy level . Each electron shell occupies a specific distance from the nucleus.
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Biol_1001_Chap2 - 1 NOTES FOR BIOLOGY 1001 SECTIONS 003 and...

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