science chapter 3, chemicals

•  a mixture is a substance that is made up of two or more substances that are not chemically combined together.
• a compound is a substance that is made up of two or more different elements that are chemically combined together.
• a element cannot be broken down in simpler substances by chemical methods.
• chemical composition is the chemical components that make up a substance.
• depending on their chemical composition, matter can be classified.
• elements are the basic building blocks of all matters
• all matters in its simplest form is a element
• why is hydrogen a element?

  this is because hydrogen cannot be further broken down, and are thus considered to be elements.
• elements can occur naturally on their own as solid, liquid and gas
• elements can be combined with other elements
• all known elements are classified according to similarities in properties
• the zig-zag line or the hays McDaniel line is used to separate metals and non metals
• compounds do not share the same properties as elements from which it is made
• the elements that are combined together to make a compound are combined together in a fixed proportion by mass
• a compound cannot be broken down into its components easily
• the substances in a mixture are not combined by the same proportion
• a mixture can be separated into its components easily
• a solvent is added to dissolve the solute
• what are suspensions?

  suspensions are mixtures that contains insoluble substances
• suspensions:

  • insoluble substances can be seen
  • insoluble substances can settle to form solid deposits
  • light cannot pass through fully
• solutions are mixtures that contains only soluble substances in a solvent
• solutions

  • particles of the solute cannot be seen
  • a solute does not settle to form solid deposits
  • light can pass through fully
• the type of solute affects the solubility of something
• factors affecting the rate of dissolving:

  • the temperature of a solvent
  • size of solute particles
  • the rate of stirring
• temperature of a solvent : why?

  when the temperature of a solvent is higher, the faster the solute will dissolve
• size of solute particles: why?

  the smaller the solute particles, the faster the solute will dissolve, as there would be a larger surface area in contact with the solvent.
• rate of stirring: why?

  the faster at the rate which we stir, the faster the solute would melt