Chemistry of Life Chemical formulas show how atoms combine Elements and Compounds Element- a substance with only one type of atom. (gold, silver, oxygen) Compound- a substance with more than one type of atom. A molecule is the smallest part of a compound. (water, glucose) Empirical Formula- expresses the composition of atoms in a molecule in the lowest terms. H2O NaCl CH2O

Chemistry of Life Molecular Formulas- shows the composition of atoms in a molecule in exact terms. C6H12O6 C3H6O3 C8H16O8 H2O CH4 pair of shared electrons Structural Formulas- shows the actual structure of a molecule, each line in the model representing a pair of shared electrons.

Chemistry of Life The Atom and its Arrangement. 0- neutron + proton - electron

Chemistry of Life Radioisotopes- An isotope is an atom of the same element that has a different number of neutron. A radioisotope is a radioactive isotope that can be used as a tracer in medicine or to find the route of atoms in a biochemical pathway. After taking a radioisotope

Chemistry of Life Types of Bonds Ionic Bonds- transfer of electrons to a recipient from a donor. Bond is due to the attraction of oppositely charged atoms. Covalent Bonds- electrons are shared by 2 atoms making the bond very strong.

Chemistry of Life Acids, Bases and Salts! Acids- Characteristics- Contain hydrogen covalently bonded to another group or single atom When compounds dissolve H+ is dissociated. The rest forms a negative ion. Sour taste Ex. HCl, H2SO4 HCl H+ + Cl-

Chemistry of Life Bases-Characteristics- Contain hydroxyl ions (OH-) in an ionic state When compounds dissolve in water, the OH- is dissociated, the rest forms a positive ion. Slippery in touch Ex. NaOH, NH3 NaOH Na+ + OH- NH3 + H2O NH4 + + OH-

Chemistry of Life Salts- Characteristics- Acid + Base Salt + Water Ex. CaOH + HCl CaCl + H2O Ex. NaOH + HCl NaCl + H2O Dissociation of Water Water is neutral even though: H2O H+ + OH- in small proportions Why???????

Chemistry of Life pH Scale (percent Hydrogen) In acids- there is more H+ than in H2O In bases there is less H+ Each number on the scale means a change of 10x. pH of 3 is 100x more acidic than a pH of 5

Chemistry of Life pH Indicators show a color change when pH goes above or below a certain level. pH must be just right for a chemical reaction to occur Phenolphthalein- colorless to red in pH above 10 Litmus paper turns red when pH is below 5 and blue when pH is above 8. Methyl orange- yellow to red in pH below 3. pH paper- more specific Paper changes color- compare to color chart on container

Chemistry of Life Organic Compounds versus Inorganic Compounds Organic compounds are carbon compounds that almost always contain hydrogen. Found naturally occurring in living things. Ex. Carbohydrates, Lipids, Proteins, Nucleic Acids Inorganic Compounds- do not contain carbon (there are exceptions) Ex. Water, acids, bases and salts