Basics of chemistry
Look around the room you’re in right now. In it you'll find solid objects like chairs, tables, lamps and an assortment of other solid objects. As you're reading this article and examining the room, you're dealing with gaseous materials, breathing them, smelling them or perhaps seeing clouds of gaseous materials. Finally, beside you, sitting in a cup or glass you probably have some kind of liquid to keep you refreshed as you review this material. All of the things we just examined, the solids, the gases and the liquids, all fall under the general category called, "Matter". The science of chemistry is the science of matter.
Matter is quite simple as you have hopefully seen. Matter is anything that is Solid (like your hand), Liquid (like your coffee, tea or water), or gas (the air you breath, steam from your tea pot, etc). If something can be classified as one of these three things, it is Matter. A more technically correct definition of matter is anything that has mass or takes up space.
The fact that matter can exist as a Solid, Liquid or Gas is referred to as its state. In other words, my hand exists in a solid state of matter while the air that I breath exists in a gaseous state of matter. This is a vital distinction because most matter (not all) can exist in all three states. Let’s take water for example. Water, at a standard room temperature of 20 degrees Celsius, is a liquid. This means it takes the shape of whatever container it's placed in and unlike a solid, presents very little resistance to objects being placed inside of it, so if I throw coins into a wishing well full of water, the coins will easily pass through the surface of the water and sink within it. These are the properties of water at 20 degrees Celsius. If we lower the temperature to -1 degree Celsius, the water reaches a point called the freezing point and freezes into a solid mass called ice. It has now become a solid. As a solid, it will no longer change its shape to whatever container it is placed in nor will it allow objects to enter it with very little resistance as before. Many of its physical properties have changed. If we now heat that ice to 101 degrees Celsius, the solid ice will melt into liquid water when the temperature rises above the melting point of water which is 0 degrees Celsius. When the temperature hits 100 degrees Celsius, the boiling point of water, the water will begin turning into a gaseous state called steam and will begin to float in the air as a cloud. Once again, some of its physical properties will have changed.
What we can draw from this is that most forms of matter share all three states of matter and change their state based on their freezing point, their melting point or their boiling point. In fact, although quite simplified, this is fairly accurate. All forms of matter have common properties among which, freezing point, melting point and boiling point exist. These properties usually vary considerably from other forms of matter. For example, the boiling point of Oxygen is -183 degrees Celsius and its melting point is at -210 degrees Celsius. Calcium on the other hand has a boiling point of 1484 degrees Celsius and its melting point is 839 degrees Celsius. The main thing to remember here is that most forms of matter can exist in any of the three states and that all forms of matter have properties in common that affect how the element of matter behaves.
So far we've been speaking in pretty familier terms, water, hands, tables and chairs, all of which are things we know well, but to understand chemistry, we have to start looking at things in extraordinarily smaller and simpler terms. Yes, surprisingly, chemistry deals in far simpler terms. To describe something as complicated as a hand or a wooden table in chemical terms, could take days just to break down the chemical composition. Chemistry deals with matter at the atom level. For a chemist, knowing that 64 grams of copper consists of 602 200 000 000 000 000 000 000 atoms is common knowledge. For a chemist, water is a chemical compound made up of 2 atoms of Hydrogen and one atom of Oxygen (H2O). Chemistry deals with the individual atoms that make up a substance or compound and the rules that govern the attraction, bonding and breakdown of the individual atoms that make up those same substances and compounds. Chemistry is at the core of how everything is made, where things come from and where they go.