Boiling/Melting Point

[Natalie Phan 3G]

When determining which molecule has a higher boiling/melting point, do we look at the inter or intramolecular forces?

[Margaret Xu 3C]

Hi Natalie! We look at intermolecular forces because the bonds between the molecules are being broken, not the bonds holding each molecule together. Compounds with stronger IMFs will have higher melting/boiling points.

[Nathan Lao 2I]

We would look at intermolecular forces since those are the attractions between the molecules. For example, if the IMFs are stronger in one compound, they would "stick together" more than the other compound and have a higher boiling point(more energy would be needed to break those intermolecular attractions).

[Anirudh Mahadev 1G]

We would look at intermolecular forces because those are the forces that are overcome to initiate a phase change. For example, when H2O (liquid) is evaporated into H2O(gas) the Hydrogen bonds in the liquid have been overcome to separate the molecules. The O-H bonds in each H2O molecule have not been broken.

[Ariel Guan 1H]

You look at intermolecular forces

[AmyHo2K]

We look at intermolecular forces because we want to see the interactions between the molecules.

[MCalcagnie_ 1D]

You are going to want to focus on intermolecular forces because those are between molecules, which would be separating as a result of boiling or melting. Intramolecular forces are within the individual molecules themselves, which are not being separated by the melting or boiling.

[Andre Fabian 1F]

In determining melting and boiling point, we would look at intermolecular forces, given that these are formed between molecules. In order to change the state of a species, we must first excite or slow down the individual molecules in order for them to separate (i.e. increasing the temperature to excite water molecules to turn them from a liquid to a gas).


Hope this helps!

[Uyenvy Nguyen 1D]

We would look at the intermolecular forces!
Intermolecular: between molecules
Intramolecular: within molecules

[Lorraine Medina 3E]

We would look at intermolecular forces in order to understand what is occuring between molecules. Hope this helps!

[Navdha Sharma 3J]

You would look at the intermolecular forces. As the intramolecular forces don't contribute towards the melting/boiling points.

[Binyu You]

I would say to look more into intermolecular bonds. If comparing different elements' boiling or melting point, the higher it is, the stronger the bond is. Several factors to consider to rank boiling/melting point include if hydrogen bond exist as well as the size of an element. The more protons it has, the larger its nucleus, the higher the boiling point.

[Melanie Lin 3E]

Hi Natalie! You generally look into intermolecular forces to see if the molecule is nonpolar or polar. Once you figure that out, you determine the type of intramolecular force that the molecules have with each other. So the BP and MP are mostly determined by the strength of the intramolecular forces.

[105618850]

Hey! I believe we examine intermolecular forces when determining the boiling point because we are not separating the atoms that compose the molecule, yet the forces that hold identical molecules together.

[LovepreetSran_3H]

When determining the boiling point and melting points we look at the intermolecular forces.

[Hasan Mirza 3F]

Intermolecular forces such as London forces and hydrogen bonding will require more energy to break bonds and allow boiling to occur.

[Aydin Karatas 1F]

Intermolecular forces because it is the force between or "inter" molecules are responsible for holding materials together. Melting and boiling would cause these forces to weaken. Thus, we go from solid --> liquid --> gas.

[MichaelMendozaD1F]

So do we always take the placement on the periodic table first, or simply look to electronegativity, if given?

[Muskaan Abdul-Sattar]

If a compound has higher intermolecular forces then its boiling point will be higher!

[Aria Movassaghi 1A]

You would look at intermolecular interactions because those are the interactions between molecules

[Hasan Mirza 3F]

Intermolecular forces like london dispersion and hydrogen bonding play a big role in boiling and melting points.

[Michelle Jeong 1B]

We look at inter because those are the forces between molecules, whereas intra are the forces within molecules.

[Rishab_Haldar_3B]

When determining which molecule has a higher boiling/melting point we look at intermolecular forces because it is the bond between molecules that are being made/broken.

[Juliana Misirian]

Also, the higher the London dispersion force, the higher the boiling point.

[Somin Lee]

It will be intermolecular force. Breaking or changing the intramolecular force means you are breaking or changing the bonds between each atom of a molecule. That changes the property of the molecule. While boiling and melting is just a change of physical property of the substance, intramolecular force should stay the same. Instead, it is intermolecular force (force acting between the molecules) that is broken.

[isabella garcia - 1G]

When determining melting/boiling point, we look at intermolecular forces because they are the forces that hold it together. When being melted/boiled, these are the bonds that need to be broken to initiate a phase change when being melted/boiled.

[Jonathan Liu 2I]

For changing states, we would look at intermolecular forces as they are the ones responsible for keeping water as a liquid at room temperature. When you boil water, the heat breaks the hydrogen bonds between the water molecules and not the covalent bonds of the water molecule itself.

[Mya_Chiarappa_2C]

For boiling and melting points we would look only at intermolecular force because the molecules are staying in tact, just separating from one another.

[Emma Goellner 2I]

When looking at the boiling or melting point of a compound, you would want to look at the intermolecular forces present. The stronger the intermolecular forces, the more energy needed to boil or melt the substance. This is because energy is required to break bonds. Some examples of IMFs that could contribute to a higher boiling/melting point are dipole-dipole interactions, london dispersion forces, and hydrogen bonding.

[SerenaSabedra]

Boiling/melting points break apart the bonds between atoms in a molecule, so it depends on the strength of the intermolecular forces. For example, molecules with shorter bond lengths have a higher boiling or melting point because shorter bonds are stronger and hold the molecule together.