How do you know which elements are solids, liquids, and gases at STP?

Get you self a copy of the periodic table that shows pictures of the elements. This one is good:

http://www.theodoregray.com/periodictable/Posters/Poster2.600.JPG

You will see that the majority of the elements are solids, so the easiest thing to do is to look at those that are not solids.

There are a few gases, H, He, N, O, F, Ne, Cl, Ar Kr, Xe. These are either low atomic number elements (H, He) or in the top right of the periodic table (N, O, F, Cl) or are noble gases (Ar, Kr, Xe), again far right of the periodic table.

There are only two elements that are liquids at STP, Hg and Br.

I remember that these few are liquids or gases, then the rest are solids.

To determine whether an element is a solid, liquid, or gas at standard temperature and pressure (STP), you can refer to the periodic table and consider the following guidelines:

1. Solids: Elements that are generally solid at STP are located on the left and middle of the periodic table. This includes most metals like iron (Fe), aluminum (Al), and copper (Cu). Nonmetals such as carbon (C) and sulfur (S) are also solid at STP.

2. Liquids: Mercury (Hg) is the only element that is liquid at STP. It is located in the transition metals section of the periodic table.

3. Gases: Most elements in the noble gases group (Group 18) are gases at STP. This includes helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Additionally, hydrogen (H) and oxygen (O) are also gases at STP.

Keep in mind that there are a few exceptions to these generalizations. For example, some elements can exhibit different states under different conditions. The periodic table is a useful reference for identifying the most common state of an element at STP, but it is always recommended to verify with specific experimental data in case of any anomalies.

To determine whether an element is a solid, liquid, or gas at standard temperature and pressure (STP), you need to consider the element's melting point and boiling point.

1. Look up the element's melting point: The melting point is the temperature at which a solid substance turns into a liquid. If the melting point of an element is below STP (0°C or 273 K), it indicates that the element is a solid at STP. For example, at STP, iron (Fe) is a solid because its melting point is 1538°C.

2. Check the element's boiling point: The boiling point is the temperature at which a liquid substance turns into a gas. If the boiling point of an element is below STP, it means the element is a gas at STP. For example, nitrogen (N2) is a gas at STP because its boiling point is -196°C, which is below 0°C.

3. If an element's melting point is higher than the boiling point, it suggests that the element is a solid at STP. For instance, tungsten (W) has a melting point of 3422°C and a boiling point of 5555°C, making it a solid at STP.

Remember that these are general guidelines, and there may be exceptions due to various factors. It is always recommended to consult reliable sources, such as chemistry reference books or reputable online databases, for accurate information on element states at STP.