matter

anything that has mass, occupies space, and can be perceived by our senses.

atom

smallest particle of matter that shows all properties of matter that may or may or may not exist independently.

kinetic theory of matter

explains existence of 3 states of matter and interconversion between them.

postulate 1

1. Matter is made of atoms and molecules 2. The constituent particles of a kind of matter are the same, but they differ from those of other kinds of matter.

postulate 2

particles of a state of matter are always in a state of random motion and possess kinetic energy.

kinetic energy

directly proportional to temperature

brownian motion example

pollen grains are added to water. they move in a zig-zag motion, as they fit into the intermolecular spaces between water molecules which are in constant motion.

brownian motion

zigzag random motion of suspended particles on the surface of a liquid or in air.

diffusion

intermixing of 2 or more substances due to their constant motion, which results in a uniform mixture.

example of diffusion

incense sticks or perfume sprayed into the air.

postulate 3

the particles have spaces between them.

postulate 4

the particles of matter are held together by forces of attraction.

force of attraction is inversely proportional to

intermolecular space

properties of states of matter

mass, shape, volume, packing of particles, force of attraction, intermolecular spaces, fluidity, compressibility, rigidity, diffusion.

motion of particles in solids

since there are lesser spaces between molecules, the particles vibrate about their mean position.

why does solid change to liquid on heating

the heat that is supplied is used to charge the molecules with kinetic energy so that they move faster and break the bonds, turning into liquid.

latent heat

heat taken in or out by matter to break bonds and change state without altering the temperature of the matter.

why do some solids sublime

these solids have weaker forces of attraction, so they gain the kinetic energy needed to become vapours much faster.

how can we change a gas to a solid using pressure

apply pressure and cool the gas, and it will be liquefied. further pressure and cooling will make it into a solid.

where is change of state via pressure found?

it is used in LPG cylinders. it is also found under the earths crust, where even the hardest rocks melt under extremely high pressure and temperatures

law of conservation of mass

mass can neither be created nor destroyed; it can only change from one state to the other. or in a chemical reaction, the total mass of reactants is equal to the total mass of products.

how can you prove conservation of mass

[conduct the experiment in a closed container] then compare the original mass of each element separately with the mass of the products.