Toasting bread is a chemical change since changing the bread to toast cannot be reversed. A chemical change affects the very essence of the object since the substances available at the beginning of the process are no longer available after completion of the process.
Chemical changes affect the nature of the object in question and normally occur through a chemical reaction. A physical change on the other hand can be reversed in such a way that the original object is created once again. Both physical and chemical changes do not affect the mass of the object in question since the law of conservation states that mass remains the same before and after a physical or chemical change.
Another way to look at chemical change is that the particles that make up an object are broken down into finer particles that form a new object. Once these particles have been broken down, there is no way to join them together once again. On the other hand, physical change involves rearranging f particles that make up a given object or substance.
Other examples of chemical change include the rusting of metal, milk turning sour, fuel burning, the body digesting food that has been eaten and when a piece of paper is set on fire.Learn More
Iron rusts when it comes in contact with oxygen and water. It rusts faster in acid rain and salty water. Both oxygen and water are necessary for rusting, which is an oxidation reaction.Full Answer >
Aluminum reacts with oxygen to form a layer of aluminum oxide on the outside of the metal, according to HowStuffWorks. This thin layer protects the underlying metal from corrosion caused by oxygen, water or other chemicals. Aluminum burns in oxygen with a white flame to form the trioxide aluminum (III) oxide, says WebElements. Chemists write the chemical reaction between aluminum and oxygen as: 4Al+ 3O2 = 2Al2O3.Full Answer >
Boron was discovered in 1808. French chemists Joseph-Louis Gay-Lussac and Louis-Jaques Thénard and English chemist Sir Humphry Davy independently isolated the element, and all three are credited with its discovery.Full Answer >
Noble gases are inert due to their complete electron shells. Their stable atomic structure makes the energy required to add or remove an electron prohibitively high, so the noble gases do not form compounds in natural conditions.Full Answer >