Chapter 2 Is Matter Around Us Pure? Flashcards
Define pure and impure substances.
Pure substance - contains only one type of particle.
Impure - contains more than 1 type of particles.
What are elements and compounds?
Elements are pure substances which cannot be broken down into simpler substances.
Compounds are made up of two or more elements chemically combined.
How are elements classified? Also define metalloid.
1 metal 2 non metal 3 metalloid
Elements that show properties of both metal and non metal are called metalloids or semi metal. Examples - silicon, boron.
What is a mixture? Also define homo and hetero mixtures.
Mixtures are made up of two or more elements combined in any proportion.
Homo- if the components of the mixture are uniformly mixed.
Hetero - not uniformly mixed.
Define physical and chemical changes
Physical - no new substances are formed and changes can be easily reversed.
Checmial - changes cannot be reversed. New substances are formed.
Give the formula for calculation of concentration of a solution.
Mass of solute / mass of solute+ mass of solvent x 100
What is a true solution?
A solution where solvent and solute cannot be distinguished even under a microscope.
What is a suspension and colloidal solution?
Suspension are heterogeneous mixture where solute particles do not dissolve and remain suspended.
Colloidal solutions are heterogeneous mixture in which particle size is too small to be seen with naked eyes but big enough to scatter light.
What is emulsion?
Emulsion is a colloidal solution where the dispersed phase and medium are both liquid.
