what happens properties that changed properties that didn't change
N2 + H2 --> NH3    
ice + heat --> liquid water    
Na + Cl --> NaCl    
water vapor --> ice + heat    
glass vase --> shattered pile of glass pieces    
Fe + O2 --> Fe2O3    
H2 + Cl2 --> HCl    
H2 + O2 --> H20    

hydrogen gas (H2): colorless, odorless, tasteless gas that is only slightly soluble in water; it is the least dense gas known. A jet of hydrogen burns in air with a very hot blue flame. Not harmful to breathe. The boiling point of Hydrogen is -252.87 º C The melting point of Hydrogen is -259.14 º C

Nitrogen (N2) is a colorless, odorless and tasteless gas that makes up 78.09% (by volume) of the air we breathe.  It is nonflammable and it will not support combustion. MP= -210C BP= -196C

Ammonia(NH3) is extremely soluble in water. It's a clear, colorless liquid or gas. Smelly. The reason ammonia is considered a hazardous chemical is that it is corrosive to the skin, eyes, and lungs. Ammonia Melting point : -78oC Ammonia Boiling point: -33.5oC

Sodium (Na): density = .97 g/mL (floats in water!) It’s a soft metal, reactive and with a low melting point,Sodium reacts quickly with water to produce sodium hydroxide and hydrogen. When it’s exposed to air, it loses its silvery appearance and acquires an opaque grey colour due to the formation of a sodium oxide coating. Sodium doesn’t react with nitrogen, not even at very high temperatures, but it can react with ammonia to form sodium amide. Melting Point: 97.72 °C Boiling Point: 883 °C

chlorine (Cl2): green gas. Chlorine gas is two and one half times as heavy as air, has an intensely disagreeable suffocating odor, and is exceedingly poisonous. In its liquid and solid form it is a powerful oxidizing, bleaching, and disinfecting agent. Density = 3.2 g/mL. freezing point −100.98°C; boiling point −34.6°C

NaCl: Is clear when pure, Is soluble in water. Is odourless. Molten sodium chloride is an electrical conductor. D=2.16g/mL. Boiling Point:: 1413 oC. Melting Point: 801 oC

Water: dissolves more substances than any other liquid. Density = 1g/mL Pure water is virtually colorless and has no taste or smell. B.P.= 100C M.P. 0C

Iron (Fe): density 7.8 g/mL. gray metal that is malleable and ductile. In a pure form, it is relatively soft and slightly magnetic. When hardened, it becomes much more magnetic. Boiling Point:  2750 oC. Melting Point:1535 oC

Hydrochloric acid: D= 2.1g/mL highly corrosive, strong mineral acid and has major industrial uses. It is found naturally in gastric acid. Colorloess, very soluble in water, stinky,

Rust (Fe203): magnetic, reddish color, Melting Point: 1565 oC Density = 5.24 g/mL

Oxygen gas (O2): colorless, odorless, and tasteless. Boiling Point :- 183oC. Melting Point :- 218.4oC Oxygen supports combustion, combines with most elements, and is a component of hundreds of thousands of organic compounds.