mod 1 Flashcards
what is a homogenous mixture?
all components are uniformly mixed and the composition is uniform (completely mixed) plus “uniform” means one so all the particles look the same and well blended
what is a heterogenous mixture?
the components are not completely mixed, not uniform (you are able to see particles e.g ice cream, chocolate chip cookies, a jar of jelly beans etc)
sieving
the method of solid particles of different particle size e.g separating rocks from sand (different particle sizes)
centrifugation
separating solids from a different particle size in an AQUEOUS suspension. they separate because the denser particles are forced to the bottom while the lighter ones stay at the top. even red blood cells get centrifuged
filteration
this is a method that can be used to separate solids that are already suspended in liquids or solutions e.g sand and salt can be separated by adding water to dissolve the salt and then filtering the mixture
insoluble
not being able to dissolve e.g sand cannot dissolve in water
soluble
capable of being dissolved in some solvent, usually water e.g salt actually dissolves in water
evaporation
common procedure used to separated the components of a solution, usually, boiling point is a good indicator of evaporation…
water has a boiling point of 100 degrees, salt has a boiling point of 1465 degrees.
water will evaporate first, separating from salt
miscible
liquids that mix in all proportion to form one phrase
decantation
separating different liquids by their different densities! e.g oil and water.
different from centrifuge (separating solid from liquid)
distillation
distillation, process involving the conversion of a liquid into vapour that is subsequently condensed back to liquid form
groups
periodic table has 8 groups (arranged vertically - column)
periods
each row in the periodic table is a period, AS YOU MOVE DOWN PERIODS, ELEMENTS BECOME MORE REACTIVE
group 1 trends
alkali metals
group 2
alkaline metals/transition metals
group 3
semi metals
isotopes
number of neutrons may be different, however, it has the same amount of protons and electrons (same net charge too)
why do different elements emit different wavelengths of light?
discrete energy levels associated with an atom
flame test
light is emitted when excited electrons move back to their ground state
bohr model
electrons exist in orbitals, requiring energy to jump between orbitals (think of electrons orbiting around the nucleus, the sun) it also releases energy when the energy decrease
the bohr models explained why there were specific emission of atoms, only explained by discrete shells
schrodinger model
built on from the bohr model into an entirely quantum model (electrons didnt have defined orbits)
state of matter
-elements on the left hand side of the periodic table are solid at room temperature (metals)
-non-metals (right hand side of periodic table) can be either solid, liquid or gas at room temperatures
hydrogen is a gas at room temperature
mercury and bromine are liquids at room temperature
electronegativity
determines how likely for an atom to attract an electron
-moving across a period increases electronegativity
-moving down a group decreases electronegativity
note: the greater the radii, the less electronegative an atom will be, this is because the nucleus and valance shell attract each other less
first ionisation energy
required to “rip” an electron from the neutral atom; the energy to move the first electron
-moving down a group decreases ionisation energy (less effort for greater atomic radii)
-moving across a period increase ionisation energy
