Created by Mr. Allen, FHHS The Chemistry of Life 2.1 Atoms, ions, and molecules 2.2 Properties of H2O 25 August 2014 Created by Mr. Allen, FHHS

Created by Mr. Allen, FHHS Atoms Atoms are the smallest basic unit of matter. Protons p+ have a positive charge Electrons e- have a negative charge Neutrons n0 have a neutral charge All charges are equal. Proton mass ≈ Neutron mass Electron mass << Proton mass Created by Mr. Allen, FHHS

Created by Mr. Allen, FHHS Elements An element is a particular type of atom that cannot be broken down by normal chemical means. Elements differ by the # of p+. Ex. O8 & N11 An isotope has the same # of p+ but a different number of n0. Deuterium and Tritium Illustration on board Created by Mr. Allen, FHHS

Created by Mr. Allen, FHHS Ions An ion is an atom with an uneven # of p+ and e-. Ions are created by removing or adding e-. An ionic bond, forms when one e- is transferred from one atoms to another. NaCl illustration on board. Created by Mr. Allen, FHHS

Created by Mr. Allen, FHHS Bonding Ions form to stabilize an atom ensuring that the outermost energy level is full. Covalent bonds form when atoms share a pair of electrons. CO2 example of the board. Periodic Table R36. Created by Mr. Allen, FHHS

Compounds and Molecules A compound is a substance made of different elements. Ex. H2O, CO2, CH4. A molecule is formed when two or more atoms are held together by a covalent bond. Ex. O2, N2 Created by Mr. Allen, FHHS

Created by Mr. Allen, FHHS 2.2 Properties of H2O H2O : 2 H-atoms and one O-atom. H2O is polar because of O-atom’s greater # of p+ This gives the O-atom a slight negative charge and the H-atom a slight positive charge. Illustration of polar H2O on board Created by Mr. Allen, FHHS

Created by Mr. Allen, FHHS Hydrogen Bond A slightly positive H-atom is attracted to a slightly negative atom. Leads to water having 1. High specific heat. A lot of energy needed to raise temperature. 2. Cohesive – sticks to itself 3. Adhesive – sticks to other things. Created by Mr. Allen, FHHS

Created by Mr. Allen, FHHS Solutions A solution is a mixture of substances that is the same throughout (homogeneous). Solvent: the component of the greatest quantity. Solute: the component of the smallest quantity. Ex. Blood is 95% H2O (solvent). The other 5% is mostly sugar and proteins (solutes). Polar substances dissolve other polar substances and ionic substances very well. Created by Mr. Allen, FHHS

Created by Mr. Allen, FHHS Acids, Bases, pH An acid releases H+ A base absorbs H+ pH (potential of hydrogen), scale used to measure H+ concentration. pH 7 = neutral, pH < 7 is acidic, pH > 7 is basic (aka alkaline) Created by Mr. Allen, FHHS