Chemistry Concepts Review Ideas that will help you understand photosynthesis

Key Chemical Terms Atom – The smallest particle of an element you can have that still retains the properties of that element. Molecule – Any 2 or more atoms combined chemically. Ex. O 2, N 2, F 2, H 2 O

Compound – 2 or more different atoms combined chemically. Ex. H 2 O, CO 2, C 6 H 12 O 6, CH 4

How to Read a Chemical Formula Look at the equation for photosynthesis: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 The little #’s slightly below the symbols for the elements tell you how many atoms of that element are needed to make that molecule. They are called subscript numbers. For example, in the Carbon Dioxide molecule we see a 2 below the O, that means we need 2 oxygens to connect to one Carbon to make CO 2.

Reading a Formula cont. What about the 6 in front of the CO 2 ? It is called the coefficient. It tells us how many of those molecules we need in the equation in order for the whole thing to balance. (= #’s of atoms of each type on both sides of the arrow) The arrow in an equation is read as “yields”. Things on the left side of the arrow are called “reactants”. What results after the reaction occurs shows up on the right side of the arrow and these are called the “products”. 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2

Law of Conservation of Matter Matter can be neither created nor destroyed, it can only change form. This is why chemical equations, which represent chemical reactions, must have the same # and same type of atoms on both sides of the equation. Demonstration: We got the mass of vinegar, baking soda, a balloon, and a plastic bottle. We then allowed the vinegar and baking soda to mix.

Law of Conservation of Matter Cont. A chemical reaction occurred. CH 3 COOH + NaHCO 3 CH 3 COONa + H 2 CO 3 (which breaks down rapidly into H 2 O and CO 2 ) We then looked at the mass again and saw that there was no change. No atoms were lost.

The Photosynthesis Equation So, now you know why the photosynthesis equation has the numbers in it. This keeps the equation balanced so the # of atoms in the reactants is equal to the # of atoms in the products. 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Count the # of atoms of each type of element on both sides of the equation. Is it balanced?