Intermolecular Forces Flashcards
What can some molecules gain despite having no permanent dipoles?
Instantaneous dipoles
This refers to the ability of molecules to develop temporary dipoles due to fluctuations in electron distribution.
What happens when a molecule gains an instantaneous dipole?
induces a dipole in a neighboring molecule
This process is crucial for the formation of van der Waals’ forces.
What is the role of shared electrons in the formation of a temporary dipole?
They spend more time around one nucleus, making it partially negatively charged
This uneven distribution contributes to the creation of a temporary dipole.
What influences a neighboring molecule when a temporary dipole is formed?
It induces a dipole in the neighboring molecule
This is due to the attraction of the neighboring molecule’s electrons towards the positively charged end of the temporary dipole.
What is the summary of van der Waals’ forces?
Arise from an uneven distribution of electrons resulting in temporary dipoles
The temporary dipole in one molecule can induce a dipole in another, leading to attractive forces.
How does the number of electrons affect van der Waals’ forces?
The more electrons, the stronger the van der Waals’ forces
A higher electron count leads to greater polarizability and stronger interactions.
In which substances do van der Waals’ forces occur?
All simple covalent substances
This includes a wide range of molecular compounds.
What trend is observed in boiling points as the size of the atoms increases?
Boiling points increase due to stronger van der Waals’ forces
Larger atoms have more electrons, which enhances the strength of these forces.
What type of gases are mentioned as being monatomic rather than molecular?
Noble gases
Noble gases exist as single atoms and do not form diatomic or polyatomic molecules.
How are van der Waals’ forces affected?
By the number of electrons
More electrons lead to stronger van der Waals’ interactions, affecting physical properties like boiling point.
What is the relationship between the size of a molecule and its van der Waals’ forces?
A bigger molecule has greater van der Waals’ forces.
Which element has more electrons, sulfur or phosphorus?
Sulfur has more electrons than phosphorus.
What is the chemical symbol for chlorine gas?
Cl2
Why does the melting point decrease between sulfur and chlorine?
Chlorine has fewer electrons than either phosphorus or sulfur.
What type of atomic structure does argon consist of?
Single atoms.
How does the number of electrons in argon compare to sulfur and phosphorus?
Argon has fewer electrons than both sulfur and phosphorus.
Fill in the blank: Argon has fewer _______ than the other elements.
van der Waals forces
What is the relationship between molecular size and van der Waals’ forces?
Larger molecules have more electrons and therefore have stronger van der Waals’ forces.
How do melting and boiling temperatures change with increasing chain length?
Melting and boiling temperature increases with increasing chain length.
What effect does branching have on boiling temperature?
Branching lowers the boiling temperature (increases volatility).
Why does branching lower boiling temperature?
Molecules are not able to pack closely together, resulting in weaker van der Waals’ forces.
Fill in the blank: Larger molecules have more electrons and therefore have _______.
stronger van der Waals’ forces.
True or False: Increasing chain length decreases melting and boiling temperatures.
False.
Fill in the blank: Branching increases _______ because the molecules are not able to pack closely together.
volatility.
