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Depending on temperature and some other factors, matter can exist in several states. The three most common states are known as solid, liquid and gas. A single element or compound of matter might exist in more than one state, depending on the temperature and pressure conditions. One common example is water, which can exist in solid, liquid and gaseous forms and can be readily observed in each of these states.
The state of matter can be changed by heating or cooling it or by changing the pressure conditions on it. When a material changes state, its molecules behave differently but don’t break apart. Since they remain essentially the same, they don’t form a different material but simply change the state of the existing material.
Solids
In solid materials, particles are tightly packed, which means they have a high density. This curtails their movement. Moreover, the electrons in each atom are in constant motion, so the atom has a small vibration. Nonetheless, its position remains fixed, which is why solid particles have low kinetic energy.
All solids have a definite shape, mass and volume, which prevents them from conforming to the shape and volume of a container where they are kept. This is one of the properties that differentiates solid matter from liquid matter.
Liquids
Unlike solids, particles in liquid matter are more loosely packed. This enables them to flow around each other, which gives the liquid an indefinite shape. It is this lack of a specific shape that enables liquids to conform to the shape of containers. Liquids are also less dense than solids. Both solids and liquids are difficult to compress.
Gases
In unconfined gaseous matter, particles are spread out indefinitely since they have a lot of space between them. This space is also why atoms in gases have large vibrations, and particles have high kinetic energy.
Gases can also be confined, in which case they adjust to the volume and shape of the container that confines them. Unlike solids and liquids, gases can be compressed by reducing the size of the container, which then reduces the space between particles.
A pure substance contains only one kind of matter;it can be a single element or a single chemical compound. Two or more pure substances mixed together constitute a mixture;you can always separate a mixture by simple physical means.
A heterogeneous mixture is not uniform and different samples of the mixture will have a different compositions. A homogeneous mixture, is uniform and any sample that you examine will have exactly the same composition as any other sample. Within chemistry, the most common type of homogeneous mixture is a solution.
Any pure substance, under appropriate conditions, can exist in three different states: solids, liquids and gases. States of matter are examples of physical properties of a substance. Other physical properties include appearance (shiny, dull, smooth, rough), odor, electrical conductivity, thermal conductivity, hardness and density, etc.
The kinetic molecular theory (KMT) is generally used to explain physical states of matter. The KMT suggests that atoms and molecules are always in motion and are loosely bound to each other by attractive called intermolecular forces.
In a solid, the kinetic energy (energy of motion) associated with the atoms or molecules is insufficient to break these forces and the particles are essentially fixed in place, adjacent to each other.
In a liquid, there is enough kinetic energy to break some of the attractive forces, allowing the particles to “slip and slide” next to each other, but there is not enough energy to allow them to escape.
In a gas, there is sufficient kinetic energy to totally overcome the forces and the particles have no interactions with each other.
A change of state from a solid to a liquid occurs at a defined temperature (which) called the melting point (or freezing point);this temperature is a unique physical property of the substance. The transition from a liquid to a gas, likewise, occurs at the boiling point. A direct transition from a solid to a gas is called sublimation.
An intensive property is defined as a property that is inherent to the substance and is not dependent on the sample size. Density, the ratio of mass-to-volume for a substance, is a classic example of an intensive property.
Physical changes are changes in outward appearances that do not alter the chemical nature of the substance and produce no new substance. When a chemical change occurs, a new substance is produced. Just like physical properties describe the appearance or intensive properties of a substance, chemical properties describe the set of chemical changes that are possible for that substance.
The law of mass conservation (conservation of mass) simply states, that there is no detectable change in the total mass of materials when they react chemically (undergo a chemical change) to form new substances.
Surface Tension refers to the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules.”
The force of cohesion is defined as the force of attraction between molecules of the same substance. The force of adhesion is defined as the force of attraction between different substances, such as glass and water.
As for the definitions, the tendency of two or more different molecules to bond with each other is known as adhesion, whereas the force of attraction between the same molecules is known as cohesion.
The adhesion forces can be one of the results of electrostatic forces which are exerted on different substances. The cohesive forces are associated with Van der Waals forces and hydrogen bonding that cause liquids such as water to withstand the separation.
When a glass surface is poured with water, both adhesive and cohesive forces act on the surface of the water. A strong adhesive force tends the liquid to spread over the surface whereas a strong cohesive force is responsible for the formation of water droplets on the water surface.
The adhesion and cohesion forces, both vary in their strengths. For example, if cohesion forces between the water molecules are stronger than that of the adhesion forces between them, then the individual molecules will attract each other thus resulting in settling. In case, the adhesion forces of the water surfaces are stronger than that of the cohesion forces of the water molecules, then the water tends to disperse.