Elements of Life and Water pH - PDF

Elements of Life Farzaneh Aghajani DDS, MSc, PhD Living Things are organized  Matter refers to anything that takes up space and has mass. Solid materials Nonliving...

Elements of Life Farzaneh Aghajani DDS, MSc, PhD Living Things are organized  Matter refers to anything that takes up space and has mass. Solid materials Nonliving All Gas Materials Liquid Within living things Plasma Consist of elements  What is an element? An element is a substance that cannot be broken down into simpler substances with different properties by ordinary chemical means. Only 92 naturally occurring elements serve as the building blocks of all matter including earth crust and all organism.  Six elements are basic to life and make up about 95% of the body weight:  C Carbon  H Hydrogen  N Nitrogen  O Oxygen  P Phosphorus  S Sulfur  Elements that make up 95% of Many other elements are necessary in living organisms (by weight) smaller quantities for optimal homeostasis C Carbon O Oxygen H Hydrogen P Phosphorus Sodium N Nitrogen S Sulfur Potassium Chloride Iron Calcium Iodine Zinc Copper Magnesium … Many, many more  Number of protons The sum of the protons and neutrons in the nucleus (AMU) Carbon An atom is the smallest part of an element that displays the properties of the element.  Electrons orbit the nucleus at particular energy levels (electron shells or orbitals). H C N Valence shell: the outer electron shell Most elements do not exist in nature as a single atom O P S  Molecules form when two or more atoms bond together (O2) Compounds form when molecules consist of two or more (different) elements bond together (H2O) A molecule is the smallest part of a compound that still has the properties of that compound. A reaction is a process where two or more substances interact with each other. When a chemical reaction occurs, energy may be given off or absorbed.  Bonding Types of Bonding occurs when electrons are Bonding transferred, shared or attracted to another element, molecule or Metallic Ionic Covalent compound.  Electrons possess energy, and the bonds that exist Nonpolar Polar between atoms also contain energy.  Organisms are directly dependent on chemical- Hydrogen bond energy to maintain their organization. Bond  Ionic Bonding Between metal and non-metal Ions are charged particles that form when electrons are transferred from one atom to another. Ionic compounds are held together by an attraction between oppositely charged ions called an ionic bond. Covalent Bonding In covalent bonds, atoms share electrons allowing each atom to have a completed outer shell. A covalent bond is between 2 non-metals  Nonpolar covalent bonds If the sharing between two atoms is fairly equal, the covalent bond is described as nonpolar. Polar Covalent Bonds If the sharing between two atoms is unequal, the covalent bond is described as polar. The bond is called polar because it differs in polarity (the electrical charge) across the molecule. Hydrogen Bonding  Hydrogen Bonding A hydrogen bond occurs between a slightly positive hydrogen atom of one molecule and a slightly negative O, N or F of another molecule Chemistry of Water Farzaneh Aghajani DDS, MSc, PhD  Organisms are composed of 70– 90% water. Water is a polar molecule Due to hydrogen bonding, water molecules cling together Without hydrogen bonding Melting (Freezing) point = - 100 C Vaporization = -90 C  Water is a solvent Liquid water Water has a is more high heat dense than capacity ice Properties Water is of Water Water has a high heat of cohesive vaporization Water has a Water is high surface adhesive tension  The amount of energy Properties of Water (heat) to be supplied to a given mass of a material to increase (change) its temperature by one unit. Water has a high heat capacity. Hydrogen bonds absorb and release heat energy slowly allowing living things to maintain a normal body temperature. Specific Heat 2nd: Water Has A High Heat of Vaporization The hydrogen bonds found in water require 540 calories of heat energy to be broken which leads to vaporization. Our body heat releases enough heat energy to allow vaporization of water which cools us down.  3rd Properties of Water Water is a solvent. Water is a polar molecule. It is easily attracted to other molecules and compounds. This attraction often dissolves other polar molecules or Ionic compounds.  4th Properties of Water Water molecules are cohesive and adhesive. Water molecules cling together because of hydrogen bonding (cohesion). Waters positive and negative poles allow it to adhere to polar surfaces (adhesion). Water is an excellent transport system, both outside and within living organisms. 4th Properties of Water Water molecules are cohesive and adhesive. Capillary Action - is the movement of liquid to slide through narrow areas by the attraction of molecules of the liquid to the molecules of the solid. 5th Properties of Water ▪ Water has a high surface tension ▪ Hydrogen bonding allows water to have a high surface tension. ▪ It is what causes the surface portion of liquid to be attracted to another surface, ▪ This allows some insects to walk on the surface of a pond or lake. 6th Properties of Water Frozen water is less dense than liquid water. As water molecules freeze, they are arranged into a lattice formation. This arrangement not only spread the molecules farther apart but also the weight of the ice which allows it to float. Specific weight  Acids and Bases When water ionizes (dissociates), it releases an equal number of hydrogen ions (H+) and hydroxide ions (OH-). Acids are substances that release hydrogen ions (H+) when they dissociate in water. Bases are substances that either take up hydrogen ions (H+) or release hydroxide ions (OH–). [H+] > [OH-]  [H+]=[OH-]  [H+] < [OH-]  pH Scale – Ranges from 0 - 14 – A pH below 7 is acidic [H+] > [OH-] – A pH above 7 is alkaline [OH-] > [H+] – A pH of 7 is neutral [H+] = [OH-] pH of sweat  between 4.5 and 7.0 pH of tea = Tea Average pH level black 4.9-5.5 green 7-10 chamomile, mint, fennel 6-7 lemon 3 rosehip, blackberry 2-3 Buffers and pH A buffer is a chemical(s) that keep pH within normal limits. pH of In animals, the pH of body fluids is maintained within a Acidosis blood 7 narrow range. the body has built-in mechanisms to prevent pH changes. pH of Alkalosis blood Buffers are the most important of these mechanisms. 7.8 Bicarbonate ions (HCO3-) and carbonic acid (H2CO3) found in human blood buffers the pH to 7.4.  Buffers and pH If blood gets too acidic, its pH is neutralized by bicarbonate ions H+ + HCO3- → H2CO3 If blood gets too basic, its pH is neutralized by carbonic acid OH- + H2CO3 → HCO3- + H2O Buffering System  Body’s Response pH of Chili souse = 2.8-3.7 pH of soda = 2-4 pH of coffee  5 If blood gets too acidic, its pH is neutralized by bicarbonate ions H+ + HCO3- → H2CO3  Body’s Response Too much egg white with sea water!! Or Because of indigestion (from chili and soft drink) If blood gets too basic, its pH is neutralized by carbonic acid OH- + H2CO3 → HCO3- + H2O bicarbonate ions + water  Any questions? Textbook read pages: 9-19