S1.1

Question 1

atom

def

Answer 1

= the smallest units of matter that still possess certain chemical properties

Question 2

elementary substances

Answer 2

contain atoms of a single element

Question 3

elements

def

Answer 3

• = 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)

Question 4

compounds

def

Answer 4

• 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

Question 5

The composition of matter (A. Einstein)

Answer 5

E = mc^2
E … energy (small value)
m … mass (negligible value)
c … speed of light (large value) = 3.0⋅10^8 ms

Question 6

division of matter

Answer 6

• pure substances: elements, compounds
• mixtures: homogenous, heterogenous

Question 7

classifications of matter

Answer 7

• has a mass
• occupies a volume in space
• made up of particles, atoms, molecules or ions
• particles are in constant motion

Question 8

pure substances

def, division

Answer 8

= matter with definite and constant composition
division: elements, compounds

Question 9

mixtures

def, division

Answer 9

• = 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

Question 10

homogenous mixture

Answer 10

⇒ uniform composition and properties throughout
no visible phases or boundaries

Question 11

heterogenous mixture

Answer 11

⇒ non-uniform composition, varying properties throughout
visible phases/boundaries

Question 12

methods of separation

Answer 12

1. filtration
2. evaporation
3. solvation (dissolution)
4. distillation
5. paper chromotography
6. (re)crystallization

Question 13

filtration

Answer 13

• = 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

Question 14

evaporation

Answer 14

• ⇒ 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

Question 15

solvation (dissolution)

Answer 15

• = 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

Question 16

distillation

Answer 16

• = 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

Question 17

volatility

Answer 17

= the tendency of a substance to undergo evaporation

Question 18

paper chromotography

Answer 18

• 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

Question 19

what influences a solvent’s affinity for the mobile/stationary phase?

Answer 19

• this affinity depends on the intermolecular forces between the pure substances in the mixture and the solvent or paper
• greater affinity for the mobile phase have a greater interaction with the solvent ⇒ move further up the stationary phase than those with a greater affinity for the stationary phase
• more soluble (higher polarity) components move faster
• less soluble components move slower or stay in place

Question 20

HPLC

Answer 20

• high pressure/performance liquid chromotography
• mobile phase is liquid
• faster
• only a small sample is needed

Question 21

crystallization

def, based on

Answer 21

• = the process of forming solid crystals from a solution
• based on the varied solubilities of solids at different temperatures

Question 22

recrystallization

def, based on

Answer 22

• = 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

Question 23

methodology of recrystallization

Answer 23

1. dissolve the impure mixture in a volume of hot solvent that is just enough to completely dissolve it ⇒ insoluble impurities can be filtered off
2. 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

Question 24

kinetic molecular theory

Answer 24

• 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)

Question 25

states of matter

Answer 25

solid
liquid
gas
plasma

Question 26

solids

kin energy, space between particles, V, shape, f of attr., density

Answer 26

• 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

Question 27

liquid

particle placement, f of attr., V, shape

Answer 27

• 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

Question 28

p(H2O)

density

Answer 28

1 g/cm^3
1000 kg/m^3

Question 29

gasses

V, shape, f of attr, particle placement, kin energy

Answer 29

• 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

Question 30

plasma

Answer 30

• = ionized gas mostly found in space
• atoms in plasma become increasingly ionized
• free electrons move among positively charged ions

Question 31

endothermic phase changes

Answer 31

• melting (solid to liquid)
• vaporization (liquid to gas)
• sublimation (solid to gas)

absorb energy/heat => to break bonds

Question 32

exothermic phase changes

Answer 32

• freezing (liquid to solid)
• condensation (gas to liquid)
• deposition (gas to solid)

release energy/heat => to form stronger bonds

Question 33

vaporization vs boiling vs evaporation

Answer 33

• 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

Question 34

Kelvins

Answer 34

• SI unit of temperature
• absolute zero ⇒ the movement of all particles stops (T = 0K = -273°C)
• T(K) = T(°C) + 273.15