1.1.1. The Science of Chemistry. Chemistry is the branch of science that studies substances and their transformations into other substances.
A process in which a substance is transformed into another substance is called a chemical reaction
. Click here
to watch some spectacular chemical reactions. If you are interested in seeing more, I can highly recommend this channel
and some of its video demonstrations, particularly The Colors of Chemistry
, The Fun of Chemistry
, 7 Minutes of Joy with Chemistry Experiments
, 8 Minutes of Joy with Chemistry Experiments
, 12 Captivating Chemistry Experiments
, and Chemistry is Enchanting
. Have fun watching! 1.1.2. Are Chemistry and Chemicals Dangerous?
Are the knife and fork that we use when we eat dangerous? They well may be if we do not know how to use them properly. This equally applies to electricity and numerous tools that are used on a daily basis, such as hammers, drills, saws, etc. Some substances that chemistry deals with are safe, whereas some others are hazardous due to their toxicity, flammability or explosiveness. 1.1.3. If Some Chemicals Are Hazardous, Why Do We Need to Deal with Them?
If some chemicals are dangerous, is it not a good idea to stay away from such chemicals altogether? Decide for yourself after reading the following two paragraphs. Cisplatin
and other anticancer drugs have saved millions of lives. Yet these drugs are very poisonous substances that would kill a person easily if taken irresponsibly in excessive quantities. We cannot imagine our lives without nylon, which is made using huge amounts of an extremely toxic chemical, hydrogen cyanide. Vast quantities of vinegar are manufactured using poisonous carbon monoxide. Hazardous chemicals are used to make numerous pharmaceuticals, polymers, materials for construction, detergents, dyes, coatings and paints, fertilizers, crop protection agents, materials for electronics used in computers and smartphones, full color displays, and so on. Just try to imagine your life without all these products.
Gasoline and other petrochemical products are flammable and can even be explosive under certain conditions. Would you like to give up on driving your car? Electricity is a wonderful alternative to gasoline, but electricity is produced in chemical processes. Even harvesting "renewable" energy from the sun and wind requires materials that cannot be made without chemicals. The modern civilized world and its standards of living are unimaginable without chemistry. Still not convinced? Watch this short video clip
and this animated cartoon
We need myriads of chemicals for myriads of our needs. To make and use all those chemicals safely, we must know chemical as well as physical, biological, and environmental properties of substances. And, we also have to use our knowledge wisely because, while holding the incredible power that paves the way to a better living, knowledge can also be "a deadly friend if no one sets the rules"
(P. Sinfield). For example, white phosphorus can be used to make phosphoric acid, which gives soft drinks that unique tingling taste that we all enjoy, but is also used in phosphorus bombs that burn, poison, and kill people. Not only do we need to make numerous varied substances and know their properties, but we also have to set the rules for how to use these substances. 1.1.4. Matter and Substance.
If, as we said above, chemistry studies substances and their transformations, what is a substance
then? To answer this question, we first need to define matter
. Everything that has a volume and mass is matter. We are matter. Animals and trees around us are matter. Air is matter. Water is matter. Matter consists of many different substances. Well, what is not matter then? Time, friendship, love, hate, our imagination, thoughts, dreams, a smile on your face are all examples of what is not matter.
A chemical substance consists of only one type of matter and has a constant composition and characteristic properties. One type of matter means molecules
of the same type (see next subsection). For example, sugar (chemical name: sucrose) is made up of molecules of only one particular type. Sugar is a substance. Water, also a substance, is made up of identical molecules of another type. However, sugar syrup, a solution of sugar in water, cannot be called a substance because it consists of molecules of two different types, molecules of sugar and molecules of water. Sugar syrup is a mixture
of two substances.