U1.1: Intro to the particulate nature of matter Flashcards
Define Atom
Smallest particle of an element
What is matter?
Anything that takes up space
Define what a pure substance is
It has definite and constant composition - it will look and remain the same
Define an Element
A substance that can’t be broken down by chemical means into simpler substances
Define a Molecule
2 or more elements that are chemically joined together
Define a Compound
2 or more elements chemically joined together in a fixed ratio
Define a Mixture
Contains more than 1 element or compound in no fixed ratio which are not chemically bonded and so can be separated by physical methods
Define a homogeneous mixture
They are the same mixtures throughout hence, they will have a uniform composition
Define a heterogeneous mixture
They have a different mixture throughout hence, they will have visibly different substances or phases throughout and therefore, a non-uniform composition
Define a Chemical Formula
Uses a combination of chemical symbols of its constituent elements
What separation technique is used to separate components of a mixture
Paper Chromatography
What separation technique is used to separate a mixture of liquids according to their boiling points
Distillation
What separation technique is used to separate mixtures according to their solubility
Filtration
What separation technique is used to separate compounds according to different, high boiling points
Fractional Distillation
What separation technique is used to separate and remove impurities that are mixed in with a solid
Recrystallisation
Define a Precipitate
A solid substance formed in a solution due to a chemical reaction or a physical change, often appearing as an insoluble product settling out of the solution.
Define vaporisation
The process in which a liquid is transformed into a gas by gaining enough energy to break intermolecular bonds.
Define sublimation
The direct transition of a substance from the solid phase to the gaseous phase, bypassing the liquid phase, by absorbing energy.
Define deposition
The direct transition of a substance from the gaseous phase to the solid phase, bypassing the liquid phase, by losing energy
Conversion formula between Kelvin and Celsius scale?
K = ˚C + 273
What is the Celsius scale?
Based on the freezing point of water (0C) and the boiling point of water (100C)
What is the Kelvin scale?
An absolute temperature scale where the lowest possible value is 0K (particles have 0 kinetic energy)
What is the temperature (in K) directly proportional to?
The temperature in Kelvin is directly proportional to the average kinetic energy of the particles in the substance
What are the 2 phases in paper chromatography
- Stationary Phase - The stationary phase is the paper
- Mobile Phase - The mobile phase is the solvent in which the sample is dissolved.
What does the degree to which the different compounds of the mixture separate (in paper chromatography) depend on
- The strength with which each component is attracted to the stationary phase (the paper)
- Its solubility in the mobile phase (the solvent)
Formula for Rf Value?
Distance traveled by solute / Distance traveled by solvent
Description of a Solid?
- Fixed lattice structure
- Particles closest together
- Strong inter-particle force
- Lowest speed of particles
Description of a Liquid?
- Particles sit at bottom of container
- Particles are touching
- Intermediate inter-particle force
- Intermediate speed of particles
Description of a Gas?
- No structure = particles take shape of the container
- Furthest apart
- Weak inter-particle force
- High speed of particles
Description of an Aqueous substance?
- Dissolved in a solvent
