B.4: Molecular View of Water

B.4: MOLECULAR VIEW OF WATER  Atoms – The atom is the smallest part of the simplest form of matter.  Elements – The simplest form of matter – all things found on the periodic table – like C = Carbon (# 6)  Each element is composed of atoms of the same type  Different elements are composed of different types of atoms  Everything on this planet is composed of a combination of the about 90 elements found in nature – including you!!

 Compounds – Two or more atoms of different

elements – like H2O, CO etc.  Molecules – Two or more atoms bonded together (of

the same or different elements) – like O2 or like H20  Chemical bond – Sharing or giving of electrons that holds molecules together B.5: SYMBOLS, FORMULAS, AND EQUATIONS  Symbols of the Elements - Like letters in the alphabet - First letter capitalized, all others lower case SODIUM = Na HYDROGEN = H CALCIUM = Ca  Chemical formulas  Like words  Combination of more than one element

o SODIUM CHLORIDE= NaCl

o CARBON DIOXIDE = CO2

o WATER = H2O . Subscripts  Tell how many atoms of each element are in each molecule  Written below and after the atom in question  The subscript 1 is understood and is not written

H2O = 2 HYDROGEN ATOMS 1 OXYGEN ATOM

CO2 = ? CARBON ATOMS ? OXYGEN ATOMS  Coefficients  The big numbers written in front of formulas  Tells how many molecules or atoms there are  Use the distributive property to apply to each formula correctly

 5 H20 = ? Hydrogen atoms ? Oxygen atoms  Chemical equations  Chemical reactions involve the breaking and forming of bonds to create new substances

 Like sentences: 2H2 + O2 2H2O  Involve Reactants . Written on the left of arrow – the stuff you start out with  Those substances reacting make Products . Written on the right of arrow – the stuff you end up with  New products formed with different chemical and physical properties than the original reactant(s)

 THE LAW OF CONSERVATION OF MATTER: THE TOTAL NUMBER OF ATOMS MUST BE THE SAME ON BOTH SIDES OF THE ARROW!!  Perform “Atom Inventory” to check

2H2 + O2 2H2O