Chapter 2: The Chemistry of Biology

The Composition of the Universe A. Element: a pure substance that cannot be broken down chemically into other kinds of matter. 1. Ex: Oxygen, Carbon, Hydrogen, Nitrogen, Phosphorus http://vimeo.com/4433312 http://www.youtube.com/watch?v=d0zION8xjbM&safety_mode=true&persist_safety_mode=1

The Composition of the Universe B. Atom: simplest part of an element C. Subatomic Particles: Parts of an atom 1. Protons: positively (+) charged particles a. Found in the nucleus of an atom 2. Neutrons: neutral particles http://www.youtube.com/watch?v=xqNSQ3OQMGI

The Composition of the Universe 3. Electrons: negatively charged particles a. Found moving around the nucleus in energy levels b. Valence electrons – electrons in the last shell or energy level of an atom ** Hint: ** The number of valence electrons for an atom, is determined by the column (group) number it falls under on the Periodic Table of Elements. For example, an atom in the 3rd column, have 3 valence electrons. http://www.youtube.com/watch?v=xqNSQ3OQMGI

The Composition of the Universe The Electron Energy Levels Bohr Model of Carbon:

The Composition of the Universe Lewis Dot Structure: http://www.youtube.com/watch?v=xqNSQ3OQMGI

The Composition of the Universe D. How do you determine the number of protons? 1. Equal to the atomic number E. How do you determine the number of electrons? 1. Equal to the # of protons (atomic number) in a stable atom F. How do you determine the number of neutrons? 1. Equal to the Atomic Mass (rounded) – Atomic #

The Composition of the Universe The Electron Energy Levels Bohr Model of Carbon:

Bonding A. All atoms “want” to be stable; if they do not have 8 valence electrons in their outer most shell, then they tend to undergo reactions to find stability 1. BONDS are then formed!

Occurs or Found Between? Bonding Type of Bond Occurs or Found Between? How is the bond formed? Additional Info Ionic Metals and Non-metals Electrons are transferred between atoms Ion: positive & negatively charged atoms formed (Na+, Cl-)

Bonding Is it easier for Potassium to gain or lose electrons to have a stable outermost ring of electrons?

Bonding What about Chlorine?

The Composition of the Universe Ionic Bonding Results

The Composition of the Universe

Occurs or Found Between? Bonding Type of Bond Occurs or Found Between? How is the bond formed? Additional Info Covalent 2 or more Non-metals Electrons are shared between atoms Can be polar or non-polar bonds depending on electron sharing

Occurs or Found Between? Bonding Type of Bond Occurs or Found Between? How is the bond formed? Additional Info Van der waals forces Between molecules (intermolecular) Oppositely charged areas of molecules are attracted to each other Very weak bonds; allows geckos to walk upside down; found between water molecules + - ATTRACTION OF DIFFERENT CHARGES BETWEEN MOLECULES

Bonding Ex: Gecko Foot – has half a million hair like projections that are divided into fibers Forces form between the hairs on the feet and surface allowing the gecko to balance gravity http://www.youtube.com/watch?v=OoYeIsSkafI

Building More Complex Substances B. Building More Complex Substances 1. Compound: substance formed by the chemical combination of atoms from two or more elements a. Ex: H2O (water), C6H12O6 (glucose), CO2 (carbon dioxide) The properties of the compound are different than those of the elements that create it!

Building More Complex Substances B. Molecule: the simplest form of a compound; when two or more atoms join 1. Ex: O2 (oxygen gas), H2O (water) *All compounds are molecules, but not all molecules are compounds**

Mixing It Up…Solutions! A. Solution: a mixture in which one or more substances are uniformly distributed in another substance. 1. Two major components a. Solute: substance dissolved into the solution b. Solvent: substance in which the solute is dissolved Ex: WATER IS THE UNIVERSAL SOLVENT

Mixing It Up…Solutions! B. How do we analyze the strength of a solution? Concentration (amount of solute dissolved in solution) 10g 20g 30g 40g 50g 100mL 100mL 100mL 100mL 100mL

pH Scale A. pH Scale: measures the concentration of hydrogen (H+) ions and hydroxide ions (OH-) in solution Range of the Scale: 0-14

pH Acid: Range: 0-7 H+ Ions: [High] OH – Ions: [Low] Ex: HCl (stomach acid), milk

pH Base: Range: 7-14 H+ ions: [Low] OH- ions: [High] Ex: Blood, Ammonia, Sea Water

pH Neutral: Range: 7 H+ ions: [Equal] OH- ions: [Equal] Ex: WATER! What are the strong acids? What are the strongest bases?

The Chemistry of Water A. COVALENT bonds: join hydrogen and oxygen that make up water 1. Electrons are not shared EQUALLY! a. Oxygen has 8 electrons b. Hydrogen only has 1 electron The oxygen atom pulls the shared electrons towards its own nucleus and away from the hydrogen.

The Chemistry of Water B. Polarity: the distribution of charges in atoms joined by a bond 1. Polar compound: a molecule with an uneven pattern of charge or unequal sharing of electrons a. Ex: Water, Sugars, Proteins, DNA (good at dissolving things!) 2. Non-polar compound: a molecule with an even pattern of charge or equal sharing of electrons a. Ex: Oxygen gas, fats, waxes + + -

Polarity of Water C. Polarity of WATER 1. Causes water molecules to attract to each other or be “sticky” and form van der waals forces between them a. Hydrogen Bond: attraction holding two+ water molecules together Positive (H+) region of one water molecule is attracted to the negative (O-) region of another These are weak bonds; they can be broken easily!

Why is hydrogen bonding important to life and biology? A. Creates cohesion of particles 1. Attractive forces between particles of the same type a. Ex: Water “sticks” allowing striders to move across; Floating a paperclip on water

Polarity of Water Surface Tension: created by cohesion; a force existing on the surface of a liquid, preventing the layer from being broken http://www.youtube.com/watch?v=8O8PuMkiimg&safety_mode=true&persist_safety_mode=1

Why is hydrogen bonding important to life and biology? B. Creates adhesion of particles 1. Attractive forces between different/unlike substances a. Ex: meniscus on a test tube

Why is hydrogen bonding important to life and biology? C. Capillary Action: water molecules move upward through narrow tubes against the force of gravity because of cohesion and adhesion 1. Ex: flower, redwood tree

Why is hydrogen bonding important to life and biology? D. High Specific Heat Capacity & Heat of Vaporization: 1. Water must gain or lose large amounts of energy (heat) to break the hydrogen bonds for any temperature change or evaporation to occur. a. Why is this important? Helps organisms maintain homeostasis Helps moderate climate/ocean water temperature

Why is hydrogen bonding important to life and biology? E. Water EXPANDS becomes LESS dense when it freezes! 1. Why is this significant? a. Ice floats preventing the water from freezing solid and insulates the lower layers, allowing life to survive underneath it

Why is hydrogen bonding important to life and biology? F. Water is the universal solvent. 1. Water dissolves more solutes than any other liquid.

Penny Lab Video http://www.youtube.com/watch?v=8O8PuMkiimg&safety_mode=true&persist_safety_mode=1