UNIT 2
.1.1 - Introduction to the particulate nature of matter
S
.1.1: Elements compounds and mixture
1
- Elements are the primary constituents of matter, which cannot be chemically broken down into simpler substances.
- Compounds consist of atoms of different elements chemically bonded together in a fixed ratio.
- Mixtures contain more than one element or compound in no fixed ratio, which are not chemically bonded and so can be separated by
physical methods.
- Pure substances have a constant composition and have distinct and consistent physical and chemical properties
- A pure substance made from only one type of atom is called an element
- Elements are defined as the primary constituents of matter, which cannot be chemically broken down into simpler substances
- A pure substance made from atoms of different elements chemically combined together in a fixed ratio is a compound.
- Impure substances are mixtures that contain more than one element or compound in no fixed ratio, which is not chemically bonded so
can be separated by physical methods.
- A homogenous mixture is a mixture which is all in the same ‘phase’. It is a mixture in which the composition is uniform
throughout.
- A heterogeneous mixture is a mixture which has parts in different ‘phases’. It is a mixture in which the composition is not
uniform throughout.
Filtration Evaporation
Solvation Chromatography
Distillation Recrystallization
, - Factors considered in choosing a method to separate the components of a mixture
- Chromatography involves solvent separation on a solid medium.
- Distillation takes advantage of differences in boiling points.
- Evaporation removes a liquid from a solution to leave a solid material.
- Filtration separates solids of different sizes or solids and liquids.
- Solvation separates soluble and insoluble solids.
- Recrystallisation separates impurities from a pure compound inan impure compound using heat and solubility.
- the products of a reaction are purified using recrystallisation. This is wherean impure compound is dissolved (theimpurities must also
be soluble in the solvent), to prepare a highly concentrated solution at a high temperature. The solution is cooled. Decreasing the
temperaturecausesthe solubility of the impuritiesto decrease. The impure substance then crystallizes before the impurities -
assuming that there was more impure substance than there were impurities
.1.2: Kinetic molecular theory
1
- The kinetic molecular theory is a model to explain physical properties of matter (solids, liquids and gasses) and changes of state.
- H ydrogen is not a gas it is just at this state in room temperature
- olids
S
- Particles in regular arrangement which are packed closely together.
- The bonds between particles were relatively strong.
- The particles vibrate on the spot.
- Shape is fixed.
- Cannot be compressed.
- Liquids
- Particles in random arrangement but still touching each other.
- The bonds between particles are relatively weak.
- The particles move around each other.
- Shape isn’t fixed
- Cannot be compressed
- Gases
- The particles spread far apart from each other.
- The bonds between particles are negligible/very weak
- The particles move quickly in all directions
- Shape isn’t fixed
- Can be compressed
.1.1 - Introduction to the particulate nature of matter
S
.1.1: Elements compounds and mixture
1
- Elements are the primary constituents of matter, which cannot be chemically broken down into simpler substances.
- Compounds consist of atoms of different elements chemically bonded together in a fixed ratio.
- Mixtures contain more than one element or compound in no fixed ratio, which are not chemically bonded and so can be separated by
physical methods.
- Pure substances have a constant composition and have distinct and consistent physical and chemical properties
- A pure substance made from only one type of atom is called an element
- Elements are defined as the primary constituents of matter, which cannot be chemically broken down into simpler substances
- A pure substance made from atoms of different elements chemically combined together in a fixed ratio is a compound.
- Impure substances are mixtures that contain more than one element or compound in no fixed ratio, which is not chemically bonded so
can be separated by physical methods.
- A homogenous mixture is a mixture which is all in the same ‘phase’. It is a mixture in which the composition is uniform
throughout.
- A heterogeneous mixture is a mixture which has parts in different ‘phases’. It is a mixture in which the composition is not
uniform throughout.
Filtration Evaporation
Solvation Chromatography
Distillation Recrystallization
, - Factors considered in choosing a method to separate the components of a mixture
- Chromatography involves solvent separation on a solid medium.
- Distillation takes advantage of differences in boiling points.
- Evaporation removes a liquid from a solution to leave a solid material.
- Filtration separates solids of different sizes or solids and liquids.
- Solvation separates soluble and insoluble solids.
- Recrystallisation separates impurities from a pure compound inan impure compound using heat and solubility.
- the products of a reaction are purified using recrystallisation. This is wherean impure compound is dissolved (theimpurities must also
be soluble in the solvent), to prepare a highly concentrated solution at a high temperature. The solution is cooled. Decreasing the
temperaturecausesthe solubility of the impuritiesto decrease. The impure substance then crystallizes before the impurities -
assuming that there was more impure substance than there were impurities
.1.2: Kinetic molecular theory
1
- The kinetic molecular theory is a model to explain physical properties of matter (solids, liquids and gasses) and changes of state.
- H ydrogen is not a gas it is just at this state in room temperature
- olids
S
- Particles in regular arrangement which are packed closely together.
- The bonds between particles were relatively strong.
- The particles vibrate on the spot.
- Shape is fixed.
- Cannot be compressed.
- Liquids
- Particles in random arrangement but still touching each other.
- The bonds between particles are relatively weak.
- The particles move around each other.
- Shape isn’t fixed
- Cannot be compressed
- Gases
- The particles spread far apart from each other.
- The bonds between particles are negligible/very weak
- The particles move quickly in all directions
- Shape isn’t fixed
- Can be compressed
