chapter 2 Atoms fall '08

chapter 2 Atoms fall '08 - Chapter 2 Chapter Atoms,...

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Unformatted text preview: Chapter 2 Chapter Atoms, Molecules, and Water Today we will investigate Today Atoms Elements of Life Molecules Bonding Why is water Why important to life important atoms atoms Atoms are? Atoms ????elements????? ????elements????? Matter is atoms atoms – Have a nucleus Protons – Have a positive charge – Has atomic mass of 1 – # determines atomic number determines atomic 92/117 Neutrons – Have no charge – Also has atomic mass of 1 atoms atoms Atoms are? Atoms – Elements – Has a nucleus Protons – Positive charge – Has atomic mass of 1 – # determines Atomic number determines Atomic 92/117 Neutrons No charge – Also has atomic mass of 1 – Has electrons Has = # of protons of – Therefore atoms Therefore neutral neutral Orbit nucleus Orbit – A given orbit = “shell” Electron shells Electron Electron shells Electron • Are energy levels of “e” orbiting a nucleus at fixed distances •Max 2e in 1st shell Electron shells Electron • Are energy levels of •Max 2e in 1st shell e orbiting nucleus at fixed distances Max 8e in all others Electron shells Electron • Are energy levels of e orbiting nucleus at fixed distances • Chemical properties of an atom are determined by the # of e in outer shell in 4 •Max 2e in 1st shell 6 5 Max 8e in all others 2 Atoms continued Atoms Atomic weight / mass – = protons + neutrons Atoms continued Atoms Atomic weight – = protons + neutrons – Isotopes = ? normal Radioactive isotopes – Spontaneously break apart = new atoms + energy 6 C 12.01 Atoms continued Atoms Atomic weight – = protons + neutrons – Isotopes = ? normal Radioactive isotopes – Spontaneously break apart = new atoms + energy PET Scan: red area = highest level of radioactivity Elements of life Elements Big 4 = H, Big H, C, N, O In humans,@ 96.3% by weight WHY??? Elements of life Elements Big 4 = H, C, N, O In humans,@ 96.3% by weight 7 Others = P, S, K, Mg, Others Cl, Na, Ca Cl, – @ 3.7% Elements of life Elements Big 4 = H, C, N, O In humans,@ 96.3% by weight 7 Others = Ca, P, K, Mg, S, Cl, Na – @ 3.7% 14 Trace = e.g. I , Fe, F Fe, 2 – 0.01% .0001 mass Hemoglobin 25 molecules molecules Inert vs. reactive Inert atoms atoms – Inert atoms have full shell reactive inert molecules molecules Inert vs. reactive Inert atoms atoms – Inert atoms have full shells reactive Molecules are ? A compound = inert molecules molecules Inert vs. reactive Inert atoms atoms – Inert atoms have full shells Molecules are ? A compound = Both formed by Both interactions between incomplete electron shells = bonds bonds reactive inert Chemical bonding (or attractive forces) (or Occurs between reactive atoms 3 types Ionic – Gives electrons Covalent – Share electrons Hydrogen Attraction of H+ to O= Chemical bonding (or attractive forces) (or Occurs between reactive atoms 3 types Ionic – Gives electrons Covalent – Share electrons Hydrogen Attraction of H+ to O= Chemicals reactions are the making and breaking of chemical bonds to form new substances with unique properties properties Ionic Chemical Bonds Ionic Ions are atoms that have lost or gained Ions electrons electrons – Max of 4 (why?: think 8) Ions are either positive or negative (+ or – Ions ions) ions) Ionic bond formation between sodium (Na) and chlorine (Cl) sodium Looking at the chart, determine the atomic number of Na and Cl. Na = atomic # = ??; Cl = atomic # = ?? Ionic bond formation between sodium (Na) and chlorine (Cl) sodium Na = atomic # = 11; Cl = atomic # = 17 What determined the atomic # ? Ionic bond formation between sodium (Na) and chlorine (Cl) sodium Na = atomic # = 11; Cl = atomic # = 17 How many protons do they have? How many electrons do they have? Ionic bond formation between sodium (Na) and chlorine (Cl) sodium Na = atomic # = 11; Cl = atomic # = 17 How many protons do they have? How many electrons do they have? Draw their shells Ionic bonds continued Ionic Outer shells want to Outer be full. be Ionic bonds continued Ionic Outer shells want to Outer be full be Na – – – – 2e in 1st shell 8e in 2nd shell 1e in 3rd shell Wants to donate an Wants electron so its outer shell has 8 electrons shell Ionic bonds continued Ionic Outer shells want to be full Na – – – – 2e in 1st shell 8e in 2nd shell 1e in 3rd shell Wants to donate an electron Wants so its outer shell has 8 electrons electrons Cl – – – – 2e in 1st shell 8e in 2nd shell 7e in 3rd shell Wants an electron in outer Wants shell so its outer shell has 8 electrons electrons Ionic bonds continued Ionic Sodium donates an e to Cl Sodium and becomes a positively charged ion charged Chlorine accepts an e from Na Chlorine and becomes a negatively charged ion charged These two oppositely charged These ions are attracted to each other, forming an ionic bond other, Both happy: have 8 in outer Both shell shell + - Covalent chemical bonds Covalent ? 1. 2. Share electrons Are the bonds of biological molecules Non­polar covalent bonds Why? Covalent chemical bonds Covalent Share electrons Are the bonds of biological molecules Nonpolar covalent bonds ? Polar covalent bonds Bonding Patterns Biological Molecules Biological Were among the first elements to form Are highly reactive therefore they readily form bonds listen Free radicals & antioxidants Free Free radicals are molecules with one or more unpaired electrons in their outer shell their Caused by chemicals, sunlight, Caused radiation, and heavy metals radiation, Free radicals & antioxidants Free There are molecules with one or There more unpaired electrons in their outer shell outer Such molecules are called free Such radicals radicals – Steals electrons to form 8e shell – The molecule that stole the e is no The longer a free radical BUT longer Free radicals & antioxidants Free There are molecules with one or more There unpaired electrons in their outer shell unpaired Such molecules are called free radicals Such free – Steals electrons to form 8e shell – The molecule that stole the e is no longer a The free radical BUT free – Molecule w/stolen e now a free radical Molecule Has different properties now Has It steals an electron, etc etc etc Chain reaction: other molecules changed – Destruction of bio molecules Alzheimer’s Cancer Free radicals & antioxidants Free A free radical is a molecule with one or free more unpaired electrons in its outer shell more – Steals electrons to form 8e shell – Molecule w/stolen e now a free radical Molecule Has different properties now Has Chain reaction: other molecules changed – Destruction of bio molecules Alzheimer’s Cancer Antioxidants neutralize them – Vitamins E & C Hydrogen Bonds Hydrogen Polar molecule Polar molecule The partial charges on The different parts of water molecules produce weak attractive forces called hydrogen bonds between the O2 and H2 atoms of the one water molecule and those of another those Hydrogen Bonds Hydrogen Polar molecule The partial charges The on different parts of water molecules produce weak attractive forces called hydrogen bonds between the O2 and H2 atoms of one water molecule and those of another another The combination of The water’s covalent and hydrogen bonds give water unique properties unique Hydrogen Bonds Hydrogen Water: life’s liquid life’s Why? Its Bonds give it uniqueness Why? Bonds – What bond(s)? Water makes up 60-90% of an organism Characteristics – Interacts with many other molecules – Tends to stick together – Supports acids, bases, or neutral conditions – Moderates temp changes – Forms ice, a solid that floats Water continued Water 1 Interacts – Its a product of or used in Its bio based reactions bio – How? Water continued Water Interacts – Its a product of or used in Its bio based reactions bio – Great solvent Solutions, solutes, & solvents because it is a polar molecule – Breaks up ionic bonds – Dissolves biological polar Dissolves molecules molecules Water continued Water Interacts – Its a product of or used in Its bio based reactions bio – Great solvent because it is a polar molecule – Breaks up ionic bonds – Dissolves biological polar Dissolves molecules molecules – Hydrophilic & hydrophobic Sugars dissolve; lipids don’t Water continued Water 2 Tends to stick Tends together together Why? Produces surface tension Highly COHESIVE Permits plants to draw water up trunks Water continued Water Tends to stick together Why? Produces surface tension Highly COHESIVE Permits plants to draw water up trunks And it is ADHESIVE also As a polar molecule, sticks to other polar molecules e.g. water pulls itself up the sides of a glass tube because both glass and water are polar molecules Water supports acidWater base solutions 3 Water is neutral, Water pH 7, but supports acid/base solutions acid/base Water supports acidWater base solutions 3 Water is neutral, pH 7, Water but supports acid/base solutions solutions As a solvent, As dissolves solutes creating solutions either higher in H either ions, acidic, pH 0-7 or higher in OH ions, basic, pH 7-14 Water supports acidWater base solutions 3 Water is neutral, pH 7, Water but supports acid/base solutions solutions As a solvent, dissolves As solutes creating solutions either higher in H ions, acidic, either pH 0-7 or higher in OH ions, basic, pH 7-14 Water as “common” solvent easily supports a multitude of pH requirements in organisms 4 Water continued Water Moderates temp Moderates – Heat energy is used to agitate molecules – Temperature measures molecule Temperature measures speed/agitation 4 Water continued Water Moderates temp Moderates – Heat energy is used to agitate molecules – Temperature measures molecule speed/agitation – Water molecules “stick” together because of hydrogen Water bonding bonding – So heat energy must first be used to “break” this So bonding AND bonding More heat energy is dedicated to keeping these bonds from More forming forming – The remaining heat energy then can “agitate” the The water molecules to raise its temp. water The energy required to heat 1 # of water 1 degree will raise The the temp of 1 # of steel 50 degrees the Water continued Water 4 Moderates temp Moderates – – – – Heat energy is used to agitate molecules Temperature measures molecule speed/agitation Temperature Water molecules “stick” together because of hydrogen bonding So heat energy must first be used to “break” this bonding AND More heat energy is dedicated to keeping these bonds from forming – The remaining heat energy then can “agitate” the water The molecules to raise its temp. molecules The energy required to heat 1 # of water 1 degree will raise the The temp of 1 # of steel 50 degrees temp – Therefore water acts as a temp buffer to surrounding Therefore environment environment As water cools the heat energy holding hydrogen bonds apart is As released heating the environment released We can sunbathe without adverse effect on body cells, since we are mostly water are Water continued Water 5 Ice – When it forms a solid, the crystal structure When formed keeps the water molecules further apart than when a liquid. apart – Therefore less dense and it floats – Acts as insulating layer to water below, thus Acts maintaining water as a liquid and permitting life to continue. life A particular atom has 15 electrons. particular How many shells does it have? How many electrons are in each shell? How many protons does the atom have? What is the atomic # of the element? What If this element has no isotopes, what is its mass? T/F All molecules are compounds and vice versa. T/F Water molecules have 2 bonds: hydrogen and T/F polar. amen ...
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This note was uploaded on 06/02/2011 for the course BIOL 110 taught by Professor Duwel during the Fall '08 term at South Carolina.

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