chemical vs physical property and some physical/chemical changes?

reacts with hydrogen to form a gas - Chemical

melting point - physical

combines with oxygen - chemical

boiling point - physical

density - physical

it burns in air - chemical

burning propane - chemical

Compounds: contain two or more pure substances and need a chemical process to seperate the constituents. Mixtures, on the other hand contain two or more substances, but can be separated by physical techniques as simple as handpicking, filteration, etc. Solutions: Contain a solvent and at least one solute. The solute is the one which is present in a lower amount. Heterogeneous: Hetero means "not uniform". A good example is sand in water. You clearly see sand and water as sand does not dissove in water. Homogeneous is "uniform", where you cannot see the contents with naked eye. Sugar solution and any solution is homogeneous. Physical changes are reversible - melting and boiling. Chemical changes are irreversible. Colloids and suspensions differ in particle size. Refer the book for exact particle sizes. Chemical properties are the properties which explain the REACTIVITY of the substance with other and tendancy of the substance to become another. It ultimately is based on the electronic structure of the element/compound. Physical properties are properties like appearance, melting point, boiling point, vap pr., etc. Hope this helps you start off. Go through your text for EXACT definitions.