Module: Intermolecular Forces
DCI: PS1.A (C) The structure and interactions of matter at the bulk
scale are determined by electrical forces within and between atoms.
PE: HS-PS1-3 Plan and
conduct an investigation to gather evidence to compare the structure of
substances at the bulk scale to infer the strength of electrical forces between
particles.
[Clarification
Statement: Emphasis is on understanding the strengths of forces between
particles, not on naming specific intermolecular forces (such as
dipole-dipole). Examples of particles could include ions, atoms, molecules, and
networked materials (such as graphite). Examples of bulk properties of
substances could include the melting point and boiling point, vapor pressure,
and surface tension.] [Assessment Boundary: Assessment does not include Raoult’s law
calculations of vapor pressure.]
The basic content of the standard is as follows.
- Matter behave at the bulk scale (the scale we are used to interacting with it) because of intermolecular forces.
-Substances that have greater intermolecular attraction are hard to pull apart, so they behave differently at the bulk scale.
- they have higher melting points
- they have higher boiling points
- they have lower vapor pressure (since fewer molecules turn to vapor)
- they have greater surface tension
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