1
Q
atom
def
A
= the smallest units of matter that still possess certain chemical properties
2
Q
elementary substances
A
contain atoms of a single element
3
Q
elements
def
A
- = 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)
4
Q
compounds
def
A
- 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
5
Q
The composition of matter (A. Einstein)
A
E = mc^2
E … energy (small value)
m … mass (negligible value)
c … speed of light (large value) = 3.0⋅10^8 ms
6
Q
division of matter
A
- pure substances: elements, compounds
- mixtures: homogenous, heterogenous
7
Q
classifications of matter
A
- has a mass
- occupies a volume in space
- made up of particles, atoms, molecules or ions
- particles are in constant motion
8
Q
pure substances
def, division
A
= matter with definite and constant composition
division: elements, compounds
9
Q
mixtures
def, division
A
- = 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
10
Q
homogeneous mixture
A
⇒ uniform composition and properties throughout
no visible phases or boundaries
11
Q
heterogeneous mixture
A
⇒ non-uniform composition, varying properties throughout
visible phases/boundaries
12
Q
methods of separation
A
- filtration
- evaporation
- solvation (dissolution)
- distillation
- paper chromotography
- (re)crystallization
13
Q
filtration
A
- = 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
14
Q
evaporation
A
- ⇒ 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
15
Q
solvation (dissolution)
A
- = 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
16
Q
distillation
A
- = 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
17
Q
volatility
A
= the tendency of a substance to undergo evaporation
18
Q
paper chromotography
A
- 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
19
Q
HPLC
A
- high pressure/performance liquid chromotography
- mobile phase is liquid
- faster
- only a small sample is needed
20
Q
crystallization
def, based on
A
- = the process of forming solid crystals from a solution
- based on the varied solubilities of solids at different temperatures
21
Q
recrystallization
def, based on
A
- = 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
22
Q
methodology of recrystallization
A
- 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
23
Q
kinetic molecular theory
A
- 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)
24
Q
states of matter
A
solid
liquid
gas
plasma
25
solids
| kin energy, space between particles, V, shape, f of attr., density
* least amount of kinetic energy
* particles are very close together with little space between them ⇒ cannot be compressed
* fixed V, shape
* strong forces of attraction between particles
* particles vibrate in fixed positions but do not move around
* tend to have higher density
26
liquid
| particle placement, f of attr., V, shape
* particles are close together with some space between them ⇒ can flow, move more freely
* forces of attraction exist, yet are weaker than in a solid
* fixed V, no fixed shape ⇒ take the shape of the bottom of the container
* cannot be compressed
* particles vibrate, rotate and move around
27
p(H2O)
| density
1 g/cm^3
1000 kg/m^3
28
gasses
| V, shape, f of attr, particle placement, kin energy
* no fixed V or shape ⇒ take on the same shape of the container itself, can be compressed
* attractive forces between particles are negligible
* particles are far apart with lots of space between them
* most amount of kinetic energy
* particles vibrate, rotate, and move around faster than in a liquid
29
plasma
* = ionized gas mostly found in space
* atoms in plasma become increasingly ionized
* free electrons move among positively charged ions
30
endothermic phase changes
* melting (solid to liquid)
* vaporization (liquid to gas)
* sublimation (solid to gas)
| absorb energy/heat => to break bonds
31
exothermic phase changes
* freezing (liquid to solid)
* condensation (gas to liquid)
* deposition (gas to solid)
| release energy/heat => to form stronger bonds
32
vaporization vs boiling vs evaporation
* **vaporization** ⇒ the general process of a liquid becoming a gas and can happen through evaporation and boiling
* **evaporation** ⇒ only at the surface of a liquid; doesn’t have to reach the boiling point
* **boiling** ⇒ throughout the liquid
* at a specific temperature; when vapor pressure reaches external pressure
33
Kelvins
* SI unit of temperature
* absolute zero ⇒ the movement of all particles stops (T = 0K = -273°C)
* T(K) = T(°C) + 273.15
