Chapter 10 Flashcards
What happens to the boiling point of an element as the atomic number increases?
the boiling point increases as the atomic number increases.
What is an induced dipole?
The separation of charge produced in an atom or molecue by a momentary uneven distribution of electrons
What are dispersion forces?(London force)
an intermolecular force between molecules caused by the presence of temporary dipoles in the molecules.
What happens to the strength of the london forces as the molecules increase?
The strengths and interactions increase as the number of electrons in atoms and molecules increase.
What is polarizability?
The relative ease with which electron clouds surrounding the nuclei of individual atoms or molecules can be distorted thereby reducing temporary diploes.
What are the trends of polarizability?
- Electrons in larger atoms are held less tightly by the nucleus and a polarized more easilty
- Greater polarizabilty leads to stronger temporary dipoles and stronger forces
What are the trends of molecule shape and dispersion forces?
The larger the molecules shape (more surface area) the greater the dipsersion forces.
There are more possibilities for dispersion forces to hold them together.
What are ion-dipole interactions?
an attractive force between an ion and a molecule that has a permanent dipole moment.
What are dipole-dipole interactions?
an attractive force between polar molecules
What are dipole-induced dipole interactions?
an attraction between a polar molecule and the oppositley hcarge pole it temporarily induces in another molecule
What is a hydrogen bond?
the strongest dipole-dipole interaction. It occurs between a hydrogen atom bonded to a small, highly electronegative element (O,N,F) and an atom of oxygen or nitrogen in another polar molecule. Molecules of HF also form hydrogen bonds.
How is the boiling point of similar molar mass substances affected by dipole-dipole interactions?
Polar substances with stronger interactins tent to have higher boiling points than substances with similar molar masses but weaker interactions.
What is the relative strength of various types of forces?
Higher relative strength
Hydrogen bonding
-
Dipole-dipole
-
Dipole-induced dipole
-
Dispersion
Lower relative strength
What is vapor pressure?
The pressure exerted by a gas at a given temperature in equilibrium with its liquid phase.
How do intermolecular forces affect vapor pressure
Vapor pressure of liquids decreases as intermolecular forces increase.
How do intermolecular forces affect boiling points?
The boiling point increases as intermolecular forces increase.
