Actually all elements can exist as solids, liquids, or gases. The determining factor is temperature and pressure that the element or compound is found in. Just like water at 0 deg Celsius, when a compound reaches it's freezing point, it will become a solid. Likewise, a compound becomes a gas when it reaches the boiling point, like water vapor at 100 deg Celsius.

Each element has its own freezing and boiling temperatures for specific pressures, so compounds also have this behavior.

What I think you might really be asking is whether other substances can be found in all three phases at one time. In lab settings, pure elements and compounds are often stored or transferred by changing the element to a more manageable phase. For example, the freezing point of ammonia is -77.7 deg Celsius and the boiling point is -33.35 deg Celsius, so it is possible for those states on Earth's surface (like the Arctic/Antarctic). However, in nature, substances that have multiple phases possible at Earth's surface likely doesn't exist in substantial amounts, if at all. So I think that water is the only compound found naturally in all three of those phases. The only possible contenders that I can think of would be carbon dioxide (dry ice, the solid form of CO₂, is stable below -78.5 deg Celsius, and it sublimates directly to gas when above that temperature) and mercury (a solid below -38.83 deg Celsius and gas above 356.73 deg Celsius, liquid mercury has been used in thermometers while mercury vapor is used in fluorescent lamps).

Anything can be found in the same three states as water. What makes water unusual is that the range of conditions on the surface of the earth are able to have all three, but you'll notice that the phases for liquid and solid water do not overlap (water freezes below 0 C and melts above 0 C). But, for example, ethyl alcohol freezes at -114 C, so any of the chemical you find on Earth will be either liquid or gas, but there are places on Mars where you could have all three together.

Thank you - that's a great question.

Mercury is a liquid at room temperature, and it freezes at -40 degrees Centigrade and boils at ~360 degrees Centigrade.

Carbon dioxide is a gas at room temperature, and it freezes at ~ -80 degrees Centigrade, which is ~ -110 degrees Fahrenheit. It's not a liquid at normal pressures, but it can be made into a liquid at pressures above 5 atmospheres. Solid carbon dioxide is called 'dry ice,' and it turns into a gas when you let it warm up.

Ammonia is a gas at room temperature. It boils at -28 degrees F and freezes at -108 degrees F.

Fluorine is a gas at room temperature. It is a liquid at about -310 degrees F and a solid at -363 degrees F.

Other materials you can check out are acetic acid, ethanol and iodine.

I remembered putting iodine crystals in a closed container when I worked in a lab, and they turned into a brownish gas.

There are millions of compounds that can go through the three states of matter. The water is a special case, because the transition temperatures are easily achievable to our daily life. To give you an example, you can try play with the periodic table: periodic table You can play with the temperature and observe the evolution of states for all of the elements. The basic idea is at low enough temperature, most of elements will freeze in the solid state; a higher temperature will make them liquid; an even higher temperature will turn them into gas. This is true for most of complex compounds as well. But you should know that the transition temperatures are quite different from one to another.

This is a really interesting question because it really makes us consider why certain compounds change state. Because state changes occur simply by adding or removing energy, all substances should be able to exist as solids, liquids, and gasses. While this is true, this will not occur naturally at temperatures that occur on Earth for all substances. Take carbon dioxide for example. It typically exists as a gas in our atmosphere, but we can cool it to make dry ice (solid carbon dioxide). While dry ice usually sublimates (moves directly from gas to solid), but under high pressure, carbon dioxide can exist as a liquid. These pressures do not occur on Earth, except when scientists specifically engineer them. Another example is liquid nitrogen, which is used to freeze cells or other experiments. Naturally, it exists as a gas but when brought to extremely low pressure it will condense into a liquid. If it was brought down to an even lower temperature (-346°F) then it will freeze into a solid. So to summarize: yes, all substances can exist in all three states of matter but on Earth, water is the only one that occurs in all three states naturally.