Chapter 2 - Day 1
Chapter 2 - Day 1 Bio 301
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This 4 page Class Notes was uploaded by Kara Nichols on Tuesday May 31, 2016. The Class Notes belongs to Bio 301 at Calhoun Community College taught by Felecia Ewing in Summer 2016. Since its upload, it has received 35 views. For similar materials see Principles of Biology 1 in Biology at Calhoun Community College.
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Date Created: 05/31/16
Principle of Biology - Felicia Ewing 5/31/2016 Important Words or Definitions Important People Important Concepts Chapter 2 Matter – refers to anything that takes up space and has mass Element – a substance that cannot be broken down by chemical means into a simpler substance Atom - Smallest building block of matter that still retains its elemental properties o Basic atoms of life: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur CHNOPS 95% - 98% of the bodyweight of all organisms o Composed of 3 subatomic particles: Proton: Location: Nucleus Mass: 1.0 AMU Electrical Charge: +1 Neutron: Location: Nucleus Mass: Slightly more than 1.0 AMU Electrical Charge: 0 (neutral) Electron: Location: Outside the nucleus in electron shells (orbitals) Mass: Almost 0 Electrical Charge: -1.0 o Periodic Table – an organized listing of all known types of atoms with some important information for each atom or element Atomic Number 1 1.009 Atomic Mass (weight) Chemical Symbol H Name of Hydrogen element Atomic Number – The number of protons found in the nucleus Never Changes 1 Electron Shell – the approximate orbital paths of electrons Valence shell – the outer most electron shell (holds eight electrons) Octet Rule – electron shells with 8 electrons are the most stable Atomic Mass – the number of protons plus the number of neutrons found in the nucleus. This is the average number, because the number of neutrons can change. Isotopes – atoms of the same element with the same number of protons, but different numbers of neutrons (therefor having a different atomic weight 12 13 14 Calculations: C C C 6 6 6 The atomic mass – the atomic number equals the number of neutrons Atoms usually have a zero net charge o Because the protons and electrons are the same amount (balanced) Na Atomic Number = 11 Mass = 23 Protons = 11 Neutrons = 12 Electrons = 11 Molecule – the smallest part of a compound that still has the properties of that compound o Why? Most atoms are unstable, so they bond with others to fulfill their outermost electron shell (valence shell) Ions – Charged particles Hydrogen o Happens when atoms gain or lose electrons Mass = 1 o Cation – positively charged ion (loses electrons) Proton = 1 o Anion – negatively charged ion (gains electrons) P Bohr Model Neutron = 0 o Neils Bohr - creator Electron = 1 e o Used to arrange the subatomic particles o Structure most often used by biologist The first shell can only contain two electrons All the other shells can hold eight electrons (Octet Rule) Need to know the first 20 elements for the test (name and symbol) Valence electrons determine reactivity o Atoms with less than the maximum number of electrons in the outer shell are reactive o Atoms are non-reactive if the valence shell is full o Atoms can: Give up electrons Accept or take electrons Share electrons with another atom to complete valence shell Compound – when atoms of two or more elements bond together o Ex. Water (H 2) Bonds o Covalent – when two orbitals overlap and electrons are shared e “Share a pair” P - P A single line drawn between two atoms e represents the sharing of 2 electrons - H – H Hydrogen Gas o 2 electrons / 1 pair O=O o Double covalent bond o 4 electrons / 2 pair Nonpolar covalent bond – when the sharing of electrons is fair and equal Methane, hydrogen gas, oxygen gas Electronegativity – the attraction of an atom for electrons Polar covalent bond – unequal sharing of electrons small ionization potential o willingness to lose or give up electrons Positive end Large value for the electron affinity o More likely to grab an electron Negative end Linus Pauling – each atom has an ability to attract electrons – this ability is called electronegativity o The element with the higher electronegativity value will win the electron tug-of-war o Bottom left to upper right increases electronegativity EXCLUDING noble gases (they are already happy with the amount of electrons they have) Metals – low electronegativity Non-metals – high electronegativity Water O - o Polar molecule o Oxygen is more electronegative than the H + H + hydrogens Therefor it has a stronger pull on the electrons o Ionic – an attraction between negatively and positively charged ions ionic bonds form between: strong electron donors o 1 or 2 electrons in valence shell Strong electron acceptor o 6 or 7 electrons in valence shell o Hydrogen – the attraction between molecules, not individual atoms. Hydrogen also has to be in a covalent bond with an electronegative atom (F, O, N, Cl) Involves the sharing of a H atom and its electrons between two or more atoms Weaker than ionic and covalent Strong when there are many together Represented by a dotted line Helps maintain structure and function in cells (DNA) Water molecules exhibit cohesion (they stick together) and adhesion (they stick to other polar materials)