0227 | Sci

• Element - a pure substance that is made up of only one kind of atom.
• Compound - a combination of two or more elements.
• Property - observable characteristic that describes an object of substance.
• Solid - definite volume and shape. molecules are closely packed.
• Liquid - definite volume, the shape of liquid depend on the container. is more loosely.
• Gas - volume depend on its temperature and pressure. molecules forces are very weak.
• Plasma - when gas gains energy. high temperatures, ionization, electrons break free from their orbital.
• bose-einstein condensate - opposite of plasma. atoms clump.
• phase changes - types of reversible change that makes the phase of matter change due to the absorption of release of heat.
• melting - process by which a substance in the solid phase turns liquid phase.
• freezing/solidification - substance in liquid phase may turn into solid by freezing it.
• vaporization - process which by a liquid turns into gas.
• evaporation - occurs when the surface of water gains heat and changes into water vapor.
• condensation - process which by a gas turns into liquid.
• sublimation - process by which solid turns into gas
• deposition - occurs when gas turns into solid.
• phase diagrams - graphical representation that shows the different changes in the phase of a substance.
• physical properties - characteristics of matter that may be observed or measured without changing the chemical composition of a substance. can be either intensive/extensive
• intensive properties - do not depend on the amount of matter present. (ex.) melting point, boiling point, density, and ability to conduct energy such as heat and electricity.
• extensive properties - properties that depend on the amount of matter. (ex.) volume, mass, weight, and length.
• physical changes - observable changes in the appearance of physical property of matter while it does not change into a new substance.
• chemical change - involves chemical reactions that may result in the formation of new substance or products
• atom - is the smallest particle of matter.
• atomic model - representation of what an atom could look based on observations and scientific evidence that describes how atom behave.
• John Dalton: in 1808, an english physicist proposed the first atomic theory after conducting a number of experiments about atoms, which he wrote in his book "A New System of Chemical Philosophy"