7TH GRADE · STRUCTURE OF MATTER
Particles of matter and diffusion
Molecules, particle motion, Brownian motion and diffusion.
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Basic Concepts
Molecular structure
Matter consists of very small particles, between which there are gaps and continuous movement.
The sizes of molecules are much smaller than usual bodies, so their properties are determined by observed effects and special instruments.
Brownian motion
Random movement of small particles in a liquid or gas due to uneven impacts of the molecules of the medium.
Pollen under a microscope changes direction without external push, showing the chaotic thermal movement of molecules.
Diffusion
Spontaneous mutual penetration of particles of contacting substances due to their thermal movement.
The smell spreads faster in warm air; in liquids the process is slower, but in solids it can take years.
Physical quantities
Ambient temperature
A quantity associated with the intensity of thermal motion of particles.
Unit: kelvin ·
Tasks on the topic
Statements, answer options and the walkthrough.