S1.1 Flashcards
the particulate nature of matter
atom
def
= the smallest units of matter that still possess certain chemical properties
elementary substances
contain atoms of a single element
elements
def
- = the primary constituents of matter, which cannot be broken down into simpler substances
- made up of the same atoms, or atoms with the same number of protons
- simplest form of matter
- can exist as individual atoms (f.i. Fe) or atoms, which are bonded together (H2)
compounds
def
- consist of atoms of different elements, which are chemically bonded together in a fixed ratio and have different properties from the constituent elements
- constituents cannot be separated using physical methods, only chemical
The composition of matter (A. Einstein)
E = mc^2
E … energy (small value)
m … mass (negligible value)
c … speed of light (large value) = 3.0⋅10^8 ms
division of matter
- pure substances: elements, compounds
- mixtures: homogenous, heterogenous
classifications of matter
- has a mass
- occupies a volume in space
- made up of particles, atoms, molecules or ions
- particles are in constant motion
pure substances
def, division
= matter with definite and constant composition
division: elements, compounds
mixtures
def, division
- = matter, which is a combination of two or more pure substances (in no fixed ratio) that retain their individual properties
- constituents are not chemically bonded, can be separated using physical methods
- division: homogenous, heterogenous
homogeneous mixture
⇒ uniform composition and properties throughout
no visible phases or boundaries
heterogeneous mixture
⇒ non-uniform composition, varying properties throughout
visible phases/boundaries
methods of separation
- filtration
- evaporation
- solvation (dissolution)
- distillation
- paper chromotography
- (re)crystallization
filtration
- = the separation of an insoluble solid from a liquid or solution in a heterogeneous mixture
- filtrate = the liquid/solution which is able to pass through the filter paper
- residue = the insoluble solid which remains on the filter paper
evaporation
- ⇒ the solution is heated in an evaporating dish → the solvent evaporates, leaving the solute behind (as the residue)
- volatile liquids are removed, solids are left
solvation (dissolution)
- = the separation of a heterogeneous mixture of two solids based on differences in solubility, which can be then separated by filtration or evaporation
- soluble substances are removed, insoluble are left
distillation
- = the separation of a liquid mixture based on the difference in volatility or boiling points between the components of the mixture
- volatile liquids are removed, non-volatile ones are left
volatility
= the tendency of a substance to undergo evaporation
paper chromotography
- used to separate a mixture of solutes in a solvent
- mobile phase = solvent undergoing separation
- stationary phase = the chromatography paper used
- the components of the mixture move through the stationary phase at different rates due to their differences in solvation
HPLC
- high pressure/performance liquid chromotography
- mobile phase is liquid
- faster
- only a small sample is needed
crystallization
def, based on
- = the process of forming solid crystals from a solution
- based on the varied solubilities of solids at different temperatures
recrystallization
def, based on
- = a separation technique, which is used to remove impurities that are mixed in with a solid
- based on the varied solubilities of solids at different temperatures
methodology of recrystallization
- dissolve the impure mixture in a volume of hot solvent that is just enough to completely dissolve it ⇒ insoluble impurities can be filtered off
- the solution is cooled to room temperature which causes the solubility of the dissolved solids to decrease ⇒ formation of crystals, leaving the soluble impurities in the solution, which are then filtered to obtain the pure product
cover with a watch glass in order to prevent evaporation and contamination
kinetic molecular theory
- all matter is made up of small particles
- all particles have kinetic energy ⇒ they are all constantly moving
- the amount of kinetic energy is proportional to the temperature of the substance ⇒ particles have greater motion at higher temperatures
- collisions between particles are elastic (no loss of kinetic energy)
states of matter
solid
liquid
gas
plasma