tailieunhanh - Lecture AP Biology - Chapter 2: The chemical context of life
Identify the four major elements; distinguish between the following pairs of terms: neutron and proton, atomic number and mass number, atomic weight and mass number; distinguish between and discuss the biological importance of the following: nonpolar covalent bonds, polar covalent bonds, ionic bonds, hydrogen bonds, and van der Waals interactions. | Ch. 2 Warm-Up What is the difference between an atom, element and compound? What are the 3 main components of an atom? What are their charges? What type of bond is found in: H2O? KCl? C6H12O6? N2? Ba(OH)2 ? Chapter 2 The Chemical Context of Life Ants & the Duroia Trees Ants use formic acid to prevent other plants from growing so that the Duroia trees can serve as their home. You Must Know The three subatomic particles and their significance. The types of bonds, how they form, and their relative strengths. I. Matter vs. Energy Matter Has mass & takes up space Affected by gravity Consists of elements and compounds Energy Moves matter Potential, kinetic Ability to do work Conversions Sound, light, heat Element “pure” substance Can’t be broken down by “ordinary” means to another substance Ex. hydrogen (H), nitrogen (N) Compound 2 or more different elements combined in a fixed ratio Ex. H2O, CO2 Elements of Life 25 elements 96% : O, C, H, N ~ 4% : P, S, Ca, K & trace elements (ex: Fe, I) Hint: Remember CHNOPS II. Atomic Structure Atom = smallest unit of matter that retains properties of an element Subatomic particles: Mass (dalton or AMU) Location Charge neutron 1 nucleus 0 proton 1 nucleus +1 electron negligible shell -1 symbol 4 2 He Atomic # (protons or electrons) Mass # (protons + neutrons) symbol 2 He 4 2 atomic # (never changes) valence e- mass # Protons = Electrons = Neutrons = 2 2 2 Isotopes # neutrons varies, but same # of protons Radioactive isotopes used as tracers (follow molecules, medical diagnosis) Uncontrolled exposure causes harm III. Chemical Bonds Strongest Bonds: Covalent: sharing of e- Polar: covalent bond between atoms that differ in electronegativity Nonpolar: e- shared equally; eg. O2 or H2 III. Chemical Bonds Strongest Bonds: Ionic: 2 ions (+/-) bond (givers/takers) Na+Cl- Affected by environment (eg. water) Weaker Bonds: Hydrogen: H of polar covalent molecule bonds to electronegative atom of other polar covalent molecules Weaker Bonds: Van der | Ch. 2 Warm-Up What is the difference between an atom, element and compound? What are the 3 main components of an atom? What are their charges? What type of bond is found in: H2O? KCl? C6H12O6? N2? Ba(OH)2 ? Chapter 2 The Chemical Context of Life Ants & the Duroia Trees Ants use formic acid to prevent other plants from growing so that the Duroia trees can serve as their home. You Must Know The three subatomic particles and their significance. The types of bonds, how they form, and their relative strengths. I. Matter vs. Energy Matter Has mass & takes up space Affected by gravity Consists of elements and compounds Energy Moves matter Potential, kinetic Ability to do work Conversions Sound, light, heat Element “pure” substance Can’t be broken down by “ordinary” means to another substance Ex. hydrogen (H), nitrogen (N) Compound 2 or more different elements combined in a fixed ratio Ex. H2O, CO2 Elements of Life 25 elements 96% : O, C, H, N ~ 4% : P, S, Ca, K & trace elements (ex: Fe, I) .
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