C1 - Atomic Structure and The Periodic Table Flashcards
what is the smallest part of an element
atom
how many different elements are there
100
how are compounds formed
chemical reactions
what do chemical reactions always involve
the formation of one or more new substances, detectable energy change
what do compounds contain
two or more elements chemically combined in fixed proportions
how can compounds be split into elements
chemical reactions
what does a mixture consist of?
2 or more elements or compounds that are not chemically combined together
how can mixtures be seperated
physical processes:
crystallisation
simple distillation
fractional distilation
chromotography
what may lead to a change or replacement to a sceintific model
new experimental evidence
before the discovery of the electron, what were atoms thought to be
tiny spheres that could not be divided
what did the discovery of the electron lead to
the plum pudding model of the atom
what did the plum pudding model suggest
the atom is a ball of positive charge with negative electrons embedded in it
what was the conclusion from the results of the alpha particle scattering experiment
the mass of an atom was concentrated at the centre/ nucleus
the nucleus was charged
how did bohr adapt the nucleur model
suggesting that electrons orbit the nucleus at specific distances
after bohr adapted the nucler model, what did further experiments lead to?
the idea the positive charge of any nucleus could be subvided into a whole number of smaller particles, each particle having the same amount of positive charge. these were called protons
what did chadwicks work provide evidence for
the existance of neutrons within the nucleus
why did new evidence from the scattering experiment lead to a change in atomic model?
as most alpha particles passed through the gold foil so most of the atom is empty space. some alpha particles were deflected back so the atom has a positively charged nucleus
relative charges of the particles in the atom
proton - +1
neutron - 0’
electron - -1
what is the number of electrons equal to
number of protons in the nucleus
what is mass number
the number of protons and neutrons there are
what is the number of protons in an atom equal to
the atomic number
what is the radius of an atom
0.1nm (1 x 10-⁸)
what is the radius of the nucleus
1 x 10-¹⁴
releative masses of protons neutrons electrons
proton - 1
neutron - 1
electron - very small
what are isotopes
the same element but different number of neutrons
what are elements in the periodic table arranged in order of
atomic number
so elements with similar properties were in the same group
why is it called a periodic table
as elements w similar chemical properties occur periodically
before the discovery of protons, neutrons and electrons, what was the periodc tabble arranged by
order of atomic weights
how did mendeleev overcome some of the problems in the periodic table
by leaving gaps for elements he thought had not been discovered
why did mendeleevs periodic table become more accepted
as he left gaps for elements he predicted were not discovered. later, these undiscovered elements were discovered and their properties matched his predictions
what are group 0 called
noble gasses
properties of noble gases
unreactive
dont easily form molecules
boiling point increases going down the group
why are group 0 elements unreactive
they have a stable arrangement of electrons, 8 on the outershell
what are group 1 elements known as
alkali metals
general word equation for group 1 metal w water
metal + water —> metal hydroxide + hydrogen
how do group 1 metals react w water
vigourosly to make hydrogen gas.
more reactive as you go down
potassium has enough energy to ignite the hydrogen
how do group 1 metals react w chlorine
vigorously and produce white chloride salts
more vigorous as you go down
how do group 1 metals react w oxygen
lithium reacts to form lithium oxide
sodium reacts to form sodium oxide and sodium peroxide
potassium makes potassium peroxide and potassium superoxide
what are the chlorides formed when group 1 reacts w chlorine at room temp
white solids
how does lithium react with water
fizzes steadily and slowly becomes smaller till it disapeares
how does sodium react w water
fizzes rapidly and forms a ball
how does potassium react w water
burns violently with sparks and a lilac flame. melts to form a ball and disappears quickly w a small explosion
what are group 7 elements known as
halogens
what do group 7 elements exist as
molecules made of pairs of atoms
what can a more reactive halogen do to a less reactive one in an aqueous solution of salt
displacement
how does the melting point of transition metals compare to group 1
higher melting points
how do the densities of transition metals compare to group 1
higher densities
how does strength and hardness of transition metlas compare to group 1
much harder and stronger
how does the reactivity of transition metals with water, oxygen and halogens compare to group 1
they have a lower reactivity
unique properties of transition metals
ions w different charges
form coloured compounds
useful for catalysts
how do lithium, sodium and potassium react with water.
lithium - fizzes steadily and slowly becomes smaller until it disappears
sodium - fizzes rapidly, melts to form a ball and quickly becomes smaller until it disappears
potassium - burns violently with sparks and a lilac flame. melts quickly to forma. ball and disappears rapidly with a small explosion.
how do group 7 react with non metals
floruine - burns and produces white iron (iii) florid
chlorine -
