What Changes If The Degree (Amount) Of Intermolecular Bonds Of A Substance Are Changed?

The three states of matter

The three states of thing tin be represented past the particle model. This model explains the properties of substances in their unlike states, as well as changes of land.

Changes of country

The diagram summarises the common changes of state.

Image showing the molecular changes from a solid, to liquid, to gas.

Some substances tin change direct from solid to gas, or from gas to solid, without becoming a liquid in betwixt. This is called sublimation . Solid carbon dioxide ('dry ice') and iodine tin can sublime .

Explaining change of state

Melting, evaporating and humid

Energy must be transferred, by heating, to a substance for these changes of state to happen. During these changes the particles proceeds energy, which is used to:

suspension some of the bonds betwixt particles during melting
overcome the remaining forces of allure between particles during evaporating or boiling

In evaporation, particles leave a liquid from its surface but. In boiling, bubbles of gas form throughout the liquid. They rise to the surface and escape to the surroundings, forming a gas.

The amount of energy needed to change state from solid to liquid, and from liquid to gas, depends on the strength of the forces between the particles of a substance. The stronger the forces of attraction, the more energy is required.

Every substance has its own melting point and humid point . The stronger the forces between particles, the higher its melting and boiling points.

The strength of the forces betwixt particles depends on the particles involved. For case, the forces between ions in an ionic solid are stronger than those betwixt molecules in water or hydrogen. This explains the melting and boiling point information in the tabular array.

Substance	Bonding type	Melting point	Boiling bespeak
Sodium chloride	Ionic	801°C	1413°C
H2o	Pocket-sized molecules	0°C	100°C
Hydrogen	Small molecules	-259°C	-252°C

Evaporation tin can have place beneath the boiling point of a substance.

Condensing and freezing

Energy is transferred from a substance to the environs when a substance condenses or freezes. This is because the forces of allure between the particles become stronger.

Predicting a physical state

The land of a substance at a given temperature tin be predicted if its melting point and boiling point are known. The table summarises how to work this out.

Temperature	Predicted country
Given temperature < melting bespeak	Solid
Given temperature is between melting and boiling points	Liquid
Given temperature > boiling point	Gas

Question: The melting point of oxygen is -218°C and its boiling indicate is -183°C. Predict the country of oxygen at -200°C.
: Oxygen will be in the liquid state at -200°C (considering this is between its melting and boiling points).