The Chemical Context of Life 2 The Chemical Context of Life Lecture Presentation by Nicole Tunbridge and Kathleen Fitzpatrick

Sodium Chlorine Sodium chloride Figure 2.2 What elements form this compound? Explain how table salt has emergent properties. Figure 2.2 The emergent properties of a compound Sodium Chlorine Sodium chloride

Table 2.1 Highlight the four elements that make up 96% of all living matter. Trace elements are listed at the bottom of the table. How are they different from essential elements? Table 2.1 Elements in the human body

Figure 2.3 Explain how natural selection might have played a role in the evolution of species that are tolerant of serpentine soils. Figure 2.3 Serpentine plant community

Figure 2.4 Label the electrons, neutrons, protons, nucleus, and electron shell. What is its atomic number and mass? Compare and contrast these models. - - + + + + Figure 2.4 Simplified models of a helium (He) atom (a) (b)

Figure 2.5 Explain the use of isotopes in this medical application. Cancerous throat tissue Figure 2.5 A PET scan, a medical use for radioactive isotopes

Third shell (highest energy level in this model) Figure 2.6 Electrons have potential energy. Explain why energy must be absorbed in a fixed amount when an electron moves farther away from the nucleus and lost when an electron moves towards the nucleus. (a) A ball bouncing down a flight of stairs provides an analogy for energy levels of electrons. Third shell (highest energy level in this model) Energy absorbed Second shell (next highest energy level) First shell (lowest energy level) Figure 2.6 Energy levels of an atom’s electrons Energy lost Atomic nucleus (b)

Figure 2.7 Which electrons are directly involved in chemical reactions between atoms? How many does lithium have? Lithium would most likely react with atoms of which column and why? Hydrogen 1H 2 Atomic number Helium 2He He Atomic mass 4.003 Element symbol First shell Electron distribution diagram Lithium 3Li Beryllium 4Be Boron 5B Carbon 6C Nitrogen 7N Oxygen 8O Fluorine 9F Neon 10Ne Second shell Sodium 11Na Magnesium 12Mg Aluminum 13Al Silicon 14Si Phosphorus 15P Sulfur 16S Chlorine 17Cl Argon 18Ar Figure 2.7 Electron distribution diagrams for the first 18 elements in the periodic table Third shell

First shell Second shell x y z Figure 2.8 What does an orbital describe and how many electrons can exist in a single orbital? First shell Second shell x y Neon, with two filled shells (10 electrons) First shell z Second shell 1s orbital 2s orbital Three 2p orbitals (a) Electron distribution diagram (b) Separate electron orbitals Figure 2.8 Electron orbitals 1s, 2s, and 2p orbitals (c) Superimposed electron orbitals

Name and Molecular Formula Figure 2.10a Why is this molecule not considered a compound? Why is the bond within this molecule considered a nonpolar covalent bond and not polar? Use the term electronegativity in your explanation. Name and Molecular Formula Electron Distribution Diagram Lewis Dot Structure and Structural Formula Space- Filling Model (a) Hydrogen (H2) H H Figure 2.10a Covalent bonding in four molecules (part 1: hydrogen)

Name and Molecular Formula Figure 2.10b Why is the bond between the two oxygen atoms considered a double bond? Name and Molecular Formula Electron Distribution Diagram Lewis Dot Structure and Structural Formula Space- Filling Model (b) Oxygen (O2) O O Figure 2.10b Covalent bonding in four molecules (part 2: oxygen)

Name and Molecular Formula Figure 2.10c Why are the hydrogen atoms not directly across from one another in the water molecule? (Think about this one!) Name and Molecular Formula Electron Distribution Diagram Lewis Dot Structure and Structural Formula Space- Filling Model (c) Water (H2O) O H Figure 2.10c Covalent bonding in four molecules (part 3: water) H

Name and Molecular Formula Figure 2.10d Are the hydrogen-carbon bonds considered polar or nonpolar? Is the molecule considered polar or nonpolar? Explain the apparent contradiction. Name and Molecular Formula Electron Distribution Diagram Lewis Dot Structure and Structural Formula Space- Filling Model (d) Methane (CH4) H H C H Figure 2.10d Covalent bonding in four molecules (part 4: methane) H

Animation: Covalent Bonds

Figure 2.11 What is a result of oxygen’s higher electronegativity relative to hydrogen’s in the water molecule? d- O H H d+ d+ Figure 2.11 Polar covalent bonds in a water molecule H2O

Figure 2.12-2 Compare and contrast covalent bonds and ionic bonds. + - Na Cl Na Cl Na Sodium atom Cl Chlorine atom Na+ Sodium ion (a cation) Cl- Chloride ion (an anion) Figure 2.12-2 Electron transfer and ionic bonding (step 2) Sodium chloride (NaCl)

Animation: Ionic Bonds

Figure 2.13 If molecules are produced from covalent bonds, what are produced from ionic bonds? Na+ Figure 2.13 A sodium chloride (NaCl) crystal Cl-

d- d+ Water (H2O) d+ Hydrogen bond d- Ammonia (NH3) d+ d+ d+ Figure 2.14 Would it be possible for hydrogen to be partially negative and create a hydrogen bond? Explain your answer. d- d+ Water (H2O) d+ Hydrogen bond d- Figure 2.14 A hydrogen bond Ammonia (NH3) d+ d+ d+

Figure 2.UN02 Explain how Van der Waals interactions between the animal’s skin and the surface allow it to defy gravity’s force. List the 4 interactions (Van der Waals, covalent, ionic, hydrogen) in order of increasing strength. Figure 2.UN02 In-text figure, gecko, p. 39

(a) Structures of endorphin and morphine Figure 2.16 If you were a pharmaceutical researcher, why would you want to learn the three dimensional shapes of naturally occurring signaling molecules? Key Carbon Nitrogen Natural endorphin Hydrogen Sulfur Oxygen Morphine (a) Structures of endorphin and morphine Natural endorphin Figure 2.16 A molecular mimic Morphine Endorphin receptors Brain cell (b) Binding to endorphin receptors

Figure 2.UN03 Write out the chemical equation for the formation of ammonia from hydrogen and nitrogen. Label the reactants and products of the reaction. Explain the role of Le Châtlier’s Principle in determining the chemical equilibrium. Figure 2.UN03 In-text figure, water formation, p. 40

Figure 2. 17 Write out the chemical equation for photosynthesis Figure 2.17 Write out the chemical equation for photosynthesis. Explain how this photo relates the reactants and products in the equation for photosynthesis. Figure 2.17 Photosynthesis: a solar-powered rearrangement of matter