Particle Theory PDF

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Particle Theory  Particle theory explains how matter changes state depending on the energy and forcespresent between the particles in the substance  The amount of energy needed to change from a solid to a liquid and from a liquid to a gas depends on the relative strength of the forces acting between the particles  There are many different types of substances which contain different amounts of elements and compounds  Since each substance contains different particles, then the amount of energy needed to induce a change of state is different for each individual substance  The stronger the forces between the particles, the higher the energy needed for melting and boiling to occur  When substances are heated, the particles absorb thermal energy which is converted into kinetic energy  Heating a solid causes its particles to vibrate more and as the temperature increases, they vibrate so much that the solid expands until the bonds break and the solid melts  On further heating, the now liquid substance expands more and some particles at the surface gain sufficient energy to overcome the intermolecular forces and evaporate  When the b.p. temperature is reached, all th

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-The physical state of a substance under certain conditions can be predicted from a given set of data Normally you are given melting and boiling point data for a substance and asked to predict its physical state in specified conditions. At temperatures below the melting point: o The substance will be in the solid state At temperatures between the melting point and the boiling point: o The substance will be in the liquid state At temperatures above the boiling point: o The substance will be in the gas state

Solids    

Strong forces of attraction between particles, particles are packed very closely together in a fixed and regular pattern Atoms vibrate in a fixed position but can’t change position or move Solids have a fixed volume and shape, and a relatively high density Solid particles have only a small amount of energy

Liquids    

There are weaker attractive forces between the particles of a substance in a liquid than in its corresponding solid form Particles are close together in an irregular, unfixed form Particles can move and slide past each other which is why liquids adopt the shape of the container they are in and also why they are able to flow Liquids have a fixed volume but not a fixed shape and have a moderate to high density

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Liquid particles have more energy than those in a solid but less than gaseous particles...