Several important compounds contain only nitrogen and oxygen. Place the following compounds in order of increasing mass percent of nitrogen. a. NO, a gas formed by the reaction of N2 with O2 in internal combustion engines b. NO2, a brown gas mainly responsible for the brownish color of photochemical smog c. N2O4, a colorless liquid used as fuel in space shuttles d. N2O, a colorless gas sometimes used as an anesthetic by dentists (known as laughing gas)
Chapter 7 Notes Periodic Properties of Elements Claude Monet painting called La rue Montorgueil (oil paints contain pigments) Elements in the same column of the table have the same number of electrons in their valence orbitals (occupied orbitals that hold electrons involved in bonding) 7.1: Development of the Periodic Table Dmitri Mendeleev of Russia and Lothar Meyer of Germany published close identification schemes (1869) Mendeleev is given the credit because he knew that there were undiscovered elements 1913: Henry Mosley developed atomic numbers o Table was originally organized by atomic weight, Mosley organized it by atomic numbers 7.2: Effective Nuclear
