Atomic structure and the periodic table Flashcards
what are atoms?
make up all substances and are the smallest part of an element that can exist
what are compounds?
a substance made of two or more elements chemically bonded together
what is an element?
a substance made up of one type of atom only
what is a mixture?
two different substances that are not chemically bonded together
how can mixtures be separated?
filtration, crystallisation, distillation, chromatography
what does soluble mean?
a substance that can dissolve in a liquid
what is a solute?
a solid which can dissolve
what does insoluble mean?
a substance that cannot dissolve in a liquid
what is a solution?
what is made up when a solid has dissolved in a liquid
radius of a nucleus
1 x 10 -14 m
relative mass of a proton
1
relative mass of a neutron
1
relative mass of an electron
very small
relative charge of a proton
+1
relative charge of a neutron
0
relative charge of an electron
-1
why do atoms have no charge?
same number of protons and electrons
same size charge - cancels out
radius of an atom
1 x 10 -10 m
what does the top number on periodic table mean?
mass number
what does the bottom number on an element mean?
atomic number
how do you calculate the number of neutrons?
mass number - atomic number
how do you calculate the number of protons
atomic number
how do you calculate the number of electrons
atomic number
what makes atoms an element?
same number of protons in all
what year did john dalton create his model of the atom?
1800s
what was john daltons atom like?
tiny spheres
atoms of particular element are all identical
they could combine to make compounds
what was jj thompsons model of the atom
plum pudding model
discovered the electron
ball of positive charge with electrons embedded
when was jj thomson’s plum pudding model discovered
1897
when was john daltons model of the atom discovered
1800s
what was geiger and marsdens experiment about the atom
fired alpha particles at a thin sheet of gold
expected alpha particles to pass straight through, but they didn’t
what was the result of the alpha particle experiment
most alpha particles passed straight through = lots of empty space
some particles were deflected = nucleus with positive charge
some particles bounced back = small, lots of mass, in the centre
which year was the alpha particle experiment
1910
what did ernest rutherford discover about the atom
new model
solid positive nucleus
negative electrons in orbit around it
which year did ernest rutherford discover his new atom
1911
which year did niels bohr discover his atom
1914
what did niels bohr discover about the atom
electrons must be orbiting the nucleus at a set distance called shells
what did james chadwick discover about the atom
third particle called a neutron
found in the nucleus
which year did james chadwick discover the neutron
1932
what is the atomic number
number of protons
what are isotopes
atoms of the same element with the same number of protons and electrons but a different number of neutrons
what are the properties of isotopes
different physical properties due to different number of neutrons
same chemical properties as. same number of electrons
some isotopes are radioactive
what is relative atomic mass
the average value that takes into account the abundance of isotopes for that element
what is the relative atomic mass equation
(mass number of isotope 1 x percentage abundance of isotope 1) + (mass number of isotope 2 x percentage abundance of isotope 2)
/
100
how are elements arranged in the modern periodic table?
order of atomic number
elements with similar properties are in groups
how do elements in each group have similar properties?
same amount of electrons in their outer shell
which year did johann obereiner discover his periodic table
1817
what did johann obereiner discover about the periodic table
groups of three elements
appearance and reactions are similar
RAM of middle element close to ram of other 2 elements in the triad
(atomic mass is important in grouping )
which year did john newlands discover his periodic table
1864
how did john newlands arrange his periodic table
known elements in order of atomic mass
law of octaves - each element similar properties to the one 8 along
properties repeating but oxygen and iron in the same group was not accepted
which year did dimitri mendeleev discover his periodic table
1869
how was mendeleev periodic table arranged
order of atomic mass
left gaps for undiscovered elements
broke his rules - switched tellurium and iodine due to having similar properties to the other group
correctly predicted properties of undiscovered elements
which year did henry moseley discover his periodic table
1913
how is henry moseleys (modern) periodic table arranged
grouped by atomic number
knowledge of isotopes explained why order based on atomic weights was not always correct
why is the periodic table called a periodic table
similar properties occur at regular intervals
what are metals
elements that react to form positive ions
what are non metals
elements that do not form positive ions
what are group 1 metals
alkali metals
how does the reactivity change when going down group 1
increases
how do group1 metals react with water
vigorously
create an alkaline solutions and hydrogen
how do group 1 metals react with oxygen
form an oxide
how do group one metals react with chlorine
form a white precipitate
how does lithium react with oxygen
burns with a pink/purple/red flame
white powdery solid
how does sodium react with oxygen
strong yellow/ orange flame
produces a white solid (sodium oxide)
how does potassium react with oxygen
large pieces produce vigorous lilac flame then
white solid
smaller ones make solid immediately
how does lithium react with water
fizzes
gradually disappears
smoke
how does sodium react with water
fizzes rapidly
melts into a ball
disappears quickly
how does potassium react with water
lilac flame
sparks
fizzed
disappears fastest
how does lithium react with chlorine
white powder
settles on sides of container
how does sodium react with chlorine
bright yellow flame
clouds of white powder settle on sides of container
how does potassium react with chlorine
more vigorous than with sodium
what happens as you go down group 1
-more electrons
-more shells
-distance between outer electron and nucleus increases
-more shielding by inner electrons
-easier to lose an electron
how does the melting and boiling point change when you go down group 1
decreases
what are group 7 halogens
poisonous non metals
exist as molecules made of pairs of atoms
what is tha appearance of fluorine
yellow gas
what is the appearance of chlorine
green gas
what is the appearance of bromine
red/ orange liquid
what is the appearance of iodine
purple solid
what is the use of fluorine
rocket fuel
what is the use of chlorine
makes drinking water
what is the use of bromine
clean water of harmful organisms
what is the use of iodine
used as an antiseptic medicine
turns brown in water
what is the trend as you go down group 7
relative molecular mass
melting point
boiling point
increase
what happens to reactivity as you go past group7
decreases
why does reactivity decrease for group 7
-more electrons
-more shells
-distance between outer electron and nucleus increases
-more shielding by inner electron
-harder to gain an electron
what is the displacement in group 7 halogens
a more reactive halogen will displace a less reactive halogen from a solution of its salt
how many electrons do group 0 noble gases have in their outer shell
8
what is the trend of reactivity in group 0
wont react with anything because they have a full outer shell
don’t form compounds and are monoatomic
how does the boiling point of noble gases change
increases with increasing relative atomic mass
what is the percentage by mass equation
% of element = (no of atoms of element x relative atomic mass / relative formula mass of compound) x 100
what is the aim of atom economy
improving greenness of chemistry
reducing waste made in chemistry industry
saving valuable raw materials
reducing money spent on binning waste from reactions
what is atom economy
a measure of the amount of starting materials that end up as useful products
what does a big percentage of atom economy mean
less waste to dispose
what is the atom economy equation
(relative formula mass of desired product from equation/ sum of
relative formula masses of all reactants from the equation ) x100
what are the similarities in chemical properties of group 1 elements compared to transition metals
react with non metals to form compounds
what are the differences in chemical properties of transition compared to group1 metals
g1 - very reactive
-form ions with +1 charge
-react with oxygen quickly
-react with water vigorously
-react with halogens easily
tm- form coloured compounds
-not very reactive
-form ions of different charges
-react with oxygen slowly
-react with water slowly
-react with halogens slowly
-used as catalysts
what are the similarities in physical properties of g1 and transition metals
good thermal / electrical conductors
what are the differences in physical properties of g1 compared to tm
tm- high melting point except hg
-malleable
- hard and strong
-high densities
g1- shiny and silver
low melting and boiling points
-low densities
-not as strong
-soft
