S1.1 Flashcards
Elements and Compounds are pure substances define pure substance
Only one type of substance and have a fixed composition
Mixtures are made by combing two or more pure substances together therefore they do not have a
fixed composition
Define element
a pure substance that is made of only one type of atom
Define molecule
a group of atoms covalently bonded together
Define allotropes
Different firmed of an element in the same physical state
Define compounds
Compounds are pure substances composed of two or more different elements combined in fixed ratios
Compounds cannot be separated using
physical methods
Mixtures are not
PURE SUBSTANCES
Mixtures contain pure substances that are not chemically bonded so they CAN be separated by
Physical Methods
Define Homogenous Mixture
Uniform composition and properties
Define Heterogeneous Mixture
Non-uniform composition and varying properties
A mixture of oil and water is a type of
heterogeneous mixture
Salt and water is an example
Homogeneous
Air is an example of
Homogenous
Components are not chemically bonded in
heterogeneous and homogenous
What are the 6 Physical Methods to obtain a pure substance from Mixtures ?
• Filtration
• Evaporation
• Solvation
• Distillation
• Paper Chromatography
• Recrystallisation
Filtration is ..
the separation of an insoluble solid from a liquid or solution
An example of Filtration is
Sand and Water (heterogeneous)
Evaporation is used
to separate a mixture which has a solute dissolved in a solvent
An example of use of evaporation is
Salt and Water
- solution heated in an evaporating dish and the solvent (water) evaporates leaving the solute(salt) behind
Solvation (heterogeneous) is
the separation of heterogeneous mixture of two solids based on differences in solubility- one soluble in the solvent the other is insoluble
After solvation what often is next
the soluble solid is dissolved in the solution and the insoluble solid can be separated by filtration. The soluble substance can be separated by evaporation
Distillation involves
the separation of a liquid mixture based on the difference in boiling points
Distillation used examples
ethanol and water
components of crude oil
Paper Chromatography is
used to separate a mixture of solutes in a solvent
In Paper chromatography the components will move further up
if they have greater affinity for the mobile phase due to having greater interaction with the solvent molecules
Recrystallisation is
used to remove impurities that are mixed in with a solid
(purify a solute dissolved in a solution)
What are the four theory’s of state of matter
• All matter is made up of small particles
• Particles all have kinetic energy which causes them to
move
• All matter occupies volume and space
•
What are the particles like in a solid
• Least amount of energy
• Held in fixed positions (vibrate around a fixed point)
• Very strong forces of attraction held between particles (fixed shape and volume)
What are the particles like in a liquid
• More spread out but still attracted to each-other
• Still forces of attraction but weaker than in a solid
• Don’t have a fixed shape tend to take the same shape as the bottom of the container
• Particles in a liquid are still close together therefore liquids can’t be compressed
What are the particles like in a gas
• Particles are very spread out (can be compressed) and move randomly
• Weakest forces of attraction
• Do not have a fixed shape or volume
During a change of state explain why temperature remains constant
because all added heat is used to overcome intermolecular forces
What is the endothermic processes in states of matter
melting
evaporation
sublimation
What is the exothermic processes in states of matter
Condensation freezing deposition
An increase in kinetic energy of the particles causes
an increase in temperature
Aqueous solutions are an example of
homogeneous mixtures
