To answer this question, let's think about what happens during condensation. We can see condensation in action when we leave out a glass filled with a cold drink on a warm day. The glass gets covered in water, due to the water in the air condensing onto the outside of the glass. Condensation is a change of state. Three of the states of matter are solid, liquid, and vapor. During condensation, matter is going from the vapor state to the liquid state. Water in the air, for instance, is in the vapor state and as it moves by the colder glass, it changes state into liquid, and is left as droplets on the outside of the glass. The opposite of this process is matter going from the liquid state to the vapor state.

Matter can go from liquid to vapor through boiling or evaporation. For instance, we can turn water into vapor by boiling it, and this makes steam (a vapor). Evaporation is the same change of state, but it converts liquid into vapor slower than boiling. You can witness evaporation, too, but over the period of days. If you leave a bowl of water out on the counter, you will see the water level in the bowl decrease little by little every day. The water is evaporating from the bowl and turning into vapor that is in the air we breathe!

solid to liquid = melting
liquid to solid =solidification or crystallization

solid to gas = sublimation
gas to solid = deposition

liquid to gas= boiling
gas to liquid= condensation

Before we answer what the opposite of condensation is, it might be a good idea to look a little more closely at what condensation itself is. Many people are most familiar with condensation as the thing that happens to your cold drink on a hot day. As if by magic, water seems to appear on the outside of your glass, although you originally only had water inside your glass! Something that might not be obvious is that the water on the outside of your glass isn't coming from inside the glass; it's actually coming from the outside air.

Just like all other matter, water can be in different phases, including solid ice, liquid water, and gaseous water vapor. It's this water vapor that is in the air around us, and when the water vapor in the air touches your cold glass, it cools down and turns back into liquid water droplets, causing your glass to "sweat".

Now that we've thought a little more about how condensation works, it's easy to think about what the opposite might be. If condensation is gaseous water vapor cooling down and turning into liquid water, the opposite process is liquid water heating up and turning into gaseous water vapor. This process is called evaporation, and you've probably seen it many times! It's what's happening whenever you see mist over a boiling pot of water, or the steam coming off of a hot bath. In general, any time you heat a liquid above a certain special temperature, it will start turning from liquid to gas (evaporation). If you have a hot gas, and you cool it to this same temperature, it will turn back into a liquid (condensation).

Condensation is the change from a gaseous (vapor) state to a liquid state. (Note that the page at this link states that condensation can also mean change from a gas to a solid; this type of change is also/commonly/more accurately called deposition.)

The opposite of condensation, a change from liquid to gas, is called vaporization. (Conversion from solid to gas can also be called vaporization, but sublimation is more specific to that case.)

As an additional note, evaporation is one mechanism of vaporization, but is limited to molecules on the surface of the liquid.

The process that is the reverse of condensation is called vaporization. Since condensation describes the process by which gas turns into a liquid, the reverse process would liquid turning into a gas. Both evaporation and boiling are types of vaporization. Evaporation occurs at the surface of a liquid, when particles of the liquid escape into the air. Boiling occurs when the temperature of the liquid is increased to its boiling point, and many particles in the entire body of liquid now have enough energy to start to escape the liquid.

Condensation is the process of a gas (water vapor) turning into a liquid. You’ve probably noticed condensation in the form of water droplets appearing on the outside of a cold soda can. The opposite process, where liquid turns into a gas, is called evaporation. If you warmed the soda up to the same temperature as the air, the condensed water on the outside would evaporate.

Condensation normally means transformation of gas to liquid, and if so then your answer is "evaporation", i.e. transformation from liquid to gas. However, some condensation consists of transformation from gas to solid, the opposite of which is sublimation.

Vaporization is the opposite or reverse of condensation. This is the change of matter from the liquid to the gas form. There are two examples of this. First is boiling, when liquid water changes into a gas below the surface of the liquid. Looking at a pot of boiling water, you would see these bubbles of gas rising to the surface. The body of water is vaporizing! Second is evaporation, a key part of the water cycle, when that water on the surface changes to the gas form.

Thanks for the question, and we’ll attack it in parts (skip to the end for the good stuff):

1. What does condensation mean in the language of science?

Condensation can be understood as taking something large and making it smaller, e.g. taking a novel and making SparkNotes summaries from it. In scientific circles, condensation refers to taking something that is in a gas/vapor/steam form and making it into a liquid, e.g. water steam being cooled into liquid water. Now, the question is how did water steam become “smaller”? Simply, how much space the water took up became less.

2. Where does condensation fit in the science of the states of chemical elements (things that make up everyday objects)?

Now, in the previous point, I mentioned water steam going into liquid water as a practical definition of condensation. This is known as a state change in science; basically, stuff changing its form, e.g. water becoming steam or ice. Each of these changes has a name: liquid water to ice is freezing and ice to liquid water is melting; ice to steam is sublimation and steam into ice is deposition; and finally, liquid water to steam is evaporation and steam to liquid water is condensation.

3. What is the opposite state to condensation?

In conclusion, as hinted to, the opposite state change to condensation, steam to liquid water, would be evaporation, liquid water turning back into steam.

I would say the opposite of condensation is evaporation! Condensation refers to a gas turning into a liquid. This can happen either because the gas got colder, or because it was pressurized (or both!). Evaporation is when a liquid turns into a gas. This can happen because the temperature of the liquid went up, or because the pressure went down!