Science Magazine May 2014 | Página 2

States of Matter

SOLID - HAS A DEFINITE VOLUME AND A DEFINITE SHAPE. SOLIDS ARE AFFECTED BY GRAVITY.

LIQUID - HAS A DEFINITE VOLUME AND NO DEFINITE SHAPE. LIQUIDS ARE AFFECTED BY GRAVITY.

GAS - HAS NO DEFINITE VOLUME AND NO DEFINITE SHAPE. MOST GASES ARE NOT AFFECTED BY GRAVITY.

PLASMA - HAS NO DEFINITE VOLUME AND NO DEFINITE SHAPE. RESPONDS STRONGLY TO ELECTROMAGNETIC FORCES.

Pure Substances

Elements

- elements are made up of atoms

- elements can be divided into three categories that have characteristic properties: metals, nonmetals, and metalloids

Compounds

- Are made up of one or more element

- To make a compound there must be a chemical reaction.

Mixtures

Solution (another name for this is homogeneous)

- you can only see one part

- you can separate by evaporation

Suspension (another name for this is a heterogeneous)

- you can see different parts

- you can separate by filter.

Mechanical Mixtures (Suspensions)

- You can see the different parts

- You can separate by filter

Colloids

- a heterogeneous mixture in which particles do not settle

- Colloidal particles are small enough to pass through most common filters.

DISSOLVING

Dissolving is the forming of a solution by mixing two or more materials together. It happens because particles attract each other and they are always moving, which are 2 parts of the Particle Model of Matter.

Example: Sugar and Water. First, the water particles pull a sugar particle away from the other particles in the crystals. Then the motion of the water particles carries it away. This makes room for more water particles to move in and attract another sugar particle. This process continues until all of the sugar is dissolved. Particles of sugar gradually move around and mix evenly throughout the water.

The rate of dissolving is how fast a solute dissolves in a solvent. We can increase the speed of a solvent by Agitation [shaking, stirring], increasing the temperature of the solvent, or by breaking the solute into smaller pieces.

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