Periodic Table Flashcards
what was Dalton’s theory
the atom was a solid sphere that was indestructible and all atoms of the same element were identical
what was JJ Thomson’s theory called
the plum pudding model
findings of Rutherford’s gold foil experiment
most particles passed straight through showing atom consisted of mainly empty space
few particles were deflected
few bounced back
structure of an atom
consists of protons, neutrons and electrons
atomic number
number of protons
mass number
number of protons and neutrons
what are isotopes
different atoms of the same element that have the same number of protons but different number of neutrons in their nuclei
why isotopes have similar chemical properties
they have the same number of electrons in their outer shell
2 ways isotopes are similar
same number protons in their nuclei
similar chemical properties
2 ways isotopes are different
different physical properties
different number of neutrons in their nuclei
what is relative atomic mass
average mass of an atom of an element relative ti 1/12th of the mass of an atom of carbon-12
how did Mendeleev arrange his elements
in order of increasing relative atomic mass
why did Mendeleev leave gaps
he assumed these elements had not been discovered yet and predicted the properties of some missing elements
3 similarities between Mendeleev’s table and modern table
elements put into groups
elements put into periods
elements with similar chemical properties put in same groups
what are group 1 metals called
the Alkali metals
what are group 7 elements called
the halogens
what are group 0 elements called
the noble gases
what does the period number show
number of occupied electron shells
what does group number show
number of electrons in the outer shell
how are G1 metals stored and why
under oil to prevent them from reacting with oxygen in the air
metal + water ——–>
metal hydroxide + hydrogen
properties of G1 metals
low densities very reactive white ionic solids low melting points soft good conductors of electricity
why reactivity increase as you go down group 1
as you go down the group, the atom gets bigger because there is one more shell of electrons. The outer electron is further away from the nucleus and is more shielded by the inner shells of electrons. The outer electron is less strongly attracted to the nucleus, so is lost more easily
what do you observe when G1 metal is added to water
fizzing
metal melts and float on water
lilac flame for K, Rb, Cs
test for hydrogen
test gas with a lighted splint, there will be a squeaky pop
chemical properties of G1 metals
react with water to produce alkaline solution
react with water, releasing hydrogen
react with acids
why is a lilac flame seen when potassium reacts with water
reaction is exothermic and hydrogen is produced. Heat energy given out ignites the hydrogen causing a lilac flame
uses of transition metals
construction
vehicles
electrical wiring
physical properties of transition metals
malleable ductile good conductors of electricity high melting points high densities shiny when polished
chemical properties of transition metals
compounds are coloured
more than 1 oxidation state
catalysts
why do halogens not conduct electricity
there are no free electrons
what happens to the boiling points of halogens as you go down group and why
increase as larger molecules have larger forces of attraction between them , so intermolecular forces become stronger as you go down the group
what happens to reactivity as you go down G7
atom get larger as there are more shells of electrons, so force of attraction between positive nucleus and incoming electron decreases. Reactivity decrease because it becomes more difficult for atom to form a negative ion
test for chlorine gas
test gas with damp blue litmus paper. Litmus first turns red and then bleaches
colour of bromine
orange
colour of iodine
brown
why are group 0 elements inert
they have a full outer shell of electrons so their atoms tend not to gain, share of lose electrons
properties of group 0 elements
colourless gases at room temp
single atoms
very low MP and BP
poor conductors of heat and electricity
uses of helium
weather balloons and airships
why is helium used in weather balloons
have low density and is non - flammable
uses of argon
added to space above wine barrels
lamps
welding
why argon is used in lamps and welding
to provide an inert atmosphere and to stop oxygen reacting with metal (oxidation) due to high temp
use of neon
illuminated signs and lasers
