chemistry Flashcards
what’s the relative mass of a neutron
1
what’s the relative mass of a proton
1 m/u
what’s the relative mass of an electron
1/2000
why are the elements in group 0 unreactive
they have a stable arrangement of electrons (full outer shell)
name two differences between newlands periodic table and the modern one
(no group zero.)
(the halogens are in group one)
the transition metals are in groups
hydrogen is in a group
why did mendeleev change the order of some of the elements when developing his periodic table
some of the elements appeared to be in the wrong group when the elements were arranged in order of relative atomic mass so he placed them into groups with similar properties
why are the elements ordered differently in the modern periodic table
most elements are mixtures of isotopes so should be arranged in order of atomic mass
what’s the size of a prokaryotic cell
0.1 - 5.0 micrometers in diameter
what’s the size of a eukaryotic cell
10 to 100 micrometers
how does the diameter of the atom effect the reactivity of group one elements (4 marker)
as the diameter increases, the reactivity increases because as the diameter increases the outer electron is further from the nucleus so the outer electron is less attracted to the nucleus so the outer electron is lost more easily
why do atoms have an overall neutral charge
protons are positive and electrons are negative and theree are the same number of each in an atom. therefore the opposite charges cancel out to make no overall charge
what’s the equation for the reaction of potassium with water
2K + 2H2O + 2KOH + H2
why is oxygen described as reduced in the reaction between sodium and oxygen?
because oxygen gains electrons
why does sodium oxide have a high melting point (3)
it has a giant structure with strong electrostatic forces of attraction between oppositely charged ions so large amounts of energy are needed to break the forces
what is an isotope?
an atom with the same proton number but different numbers or neutrons
give two reasons why the discovery of gallium six years after the publish of mendeleev’s periodic table helped the table become more accepted
1 - gallium fitted a gap that mendeleev left
2 - the properties were predicted correctly
what’s the name of elements in group 0
noble gases
what increases down group 0
boiling points
what type of particles are in a sample of neon?
atoms
what is the type of bonding in sodium?
metallic
give two ways in which the observations of alkali metals with water reactions show change in reactivity down group 1
1 - increasing rate of bubble production
2 - increasing speed of movement
out of diamond , magnesium, poly(ethene), sodium chloride and water which two substances have intermolecular forces between particles?
poly(ethene) and water
atoms were first thought to be tiny spheres that could not be divided
what particle was this
electron
what type of particle was fired at gold atoms to discover the new model of the atom
alpha particles
which scientist suggested that electrons orbit the nucleus at specific distances
bohr
what scale matches 1 x 10^-2
a sports arena of radius 100m
name three differences between the nuclear model and plum pudding model
in the plum pudding model, the atom is a ball of positive charge
the nuclear model is mostly empty space
in the nuclear model, the electrons and nucleus are separate
describe the change that niels bohr made to the nuclear model
electrons orbit the nucleus
electrons are at specific distances from the nucleus
which particle has the lowest mass
electron
what is mass number
number of protons plus number of neutrons
james chadwick proved the existence of the…
neutron
what is the test for chlorine gas
damp litmus paper turns white
describe what happens when sodium reacts with fluorine to produce sodium fluoride
sodium loses one electron fluorine gains one. an ionic bond is formed
what are two properties of ionic substances
dissolve in water
high melting point
why does pure water not conduct electricity
there’s no delocalised electrons
going down group 7….
the melting points increase because the size of the molecules increases so the intermolecular forces increase
is chlorine gas coloured, flammable or toxic
toxic
why does the mass increase in the reaction iron + chlorine —> iron chloride
because chlorine atoms are now a part of the solid (iron chloride)
what’s the modern name for atomic weight
relative atomic mass
how are elements arranged in the modem periodic table
in order of increasing atomic number
give two differences between properties of iron and sodium
iron has higher boiling point and iron is less reactive
why can carbon be used to extract nickel from nickel oxide
carbon is more reactive so will displace nickel
why does iron not belong in a group with oxygen and sulfur
iron is a metal
why did mendeleev leave gaps for undiscovered elements
so that elements with similar properties could be placed together
why are lithium sodium and potassium all in group one
all have one electron in the other shell so they have similar properties
covalent bonding takes place between…
non metals
ionic bonding takes place between
metals and non metals
what is ionic bonding
ionic bonding is the transfer of electrons from one atom to another to form oppositely charged ions. strong electrostatic forces hold these ions together
what is metallic bonding
positive metal ions are arranged regularly with a sea of delocalised electrons. the strong electrostatic forces of attraction hold the structure together
