Topic 1 - Atomic Structure Flashcards
What are the three subatomic particles? (and their charges?)
protons (+1)
neutrons (0)
electrons (-1)
What are the relative masses of the subatomic particles?
proton 1
neutron 1
electron 0.0005 or 1/2000
What does the atomic number show?
number of protons
this is always the smaller number on the periodic table
What are cations?
Positive ions
have fewer electrons than protons
What are anions?
Negative ions
have more electrons than protons
What are isotopes?
atoms with the same number of protons but different numbers of neutrons
-the number/arrangement of electrons determine chemical properties so they still have the same chemical properties but different physical properties (as they are determined by mass)
What is relative atomic mass (RAM)?
Ar
the weighted mean mass of an atom compared to 1/12th of the mass of an atom of carbon-12
What is relative isotopic mass (RIM)?
the mass of an atom of an isotope compared to 1/12th the mass of an atom of carbon-12
What is relative molecular mass (RMM)?
Mr
the average mass of a molecule or formula unit compared to 1/12th of the mass of an atom of carbon-12
RAM =
relative atomic mass
(RIM x %) + (RIM x %)
________________
100
What are mass spectrometers?
devices that are used to find out what samples are made up of by measuring the masses of their components
(this gives us the relative atomic masses and their abundances)
What is the M+ peak (on a mass spectrum)?
molecular ion peak
- this is the peak furthest to the right
- the value of the M+ peak is the same as its molecular mass
What are the axis labels on mass spectra?
y axis - relative abundance (%)
x axis - mass/charge or m/z
What is the M+1 peak (on a mass spectra)
a peak with small abundance the furthest to the right with a mass one more than its molecular mass
this is caused by an isotope
What are the different types of subshells?
s
p
d
What is the shape of a s-orbital?
sphere
What is the shape of a p-orbital?
two balloons tied together at the knot
How many orbitals are in each subshell?
1 orbital in s subshell (2e-)
3 orbitals in p subshell (6e-)
5 orbitals in d subshell (10e-)
What is an orbital?
a region of space within an atom that up to 2 electrons move within (spin in opposite directions)
Where are the shells with greatest energy positioned in comparison to the nucleus?
the shells furthest from the nucleus have most energy
What is electrons in boxes used to show?
electron configuration
the electrons in their orbitals
What is spin-pairing?
the idea that electrons in each orbital spin in opposite directions to eachother
What is subshell notation?
a way of showing electron configuration by showing how many electrons are in each subshell of each energy level
What are the three different blocks of the periodic table?
s-block (on the left)
p-block (on the right)
d-block (in the middle)
What does it mean when an electron is “excited”?
electrons are excited when they gain energy so jump to a higher energy level
What does an emission spectrum show?
the frequencies of light emitted when electrons drop down from a higher energy level to a lower one
What does the mass number show?
the total number of protons and neutrons in an atom
What is an ionisation energy?
the energy required to remove an electron from gaseous atoms
What is the first ionisation energy?
the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of 1+ ions
What factors affect ionisation energy?
- nuclear charge (more protons = greater nuclear charge = stronger the electrostatic attraction)
- shielding (more shells = more shielding = outer electrons less attracted to nucleus)
- sub-shell the electron is being removed from (closer to nucleus = more attracted)
What is the general trend of first ionisation energies across a period?
ionisation energies increase
Why do first ionisation energies generally increase across a period?
- more protons in nucleus (greater nuclear charge)
- greater attraction between outer electron and nucleus
What is the trend of first ionisation energies down a group?
ionisation energies decrease
Why do first ionisation energies decrease down a group?
- more electrons so more shells
- more shielding
- outer electrons less strongly attracted to nucleus so are easier to remove
What determines the chemical properties of an element?
electron configurations
What is periodicity?
repeating patterns across a period
Why do first ionisation energies decrease between group 2 and 3 elements?
lone electron in a p-orbital is being removed
group 3 element
Why do first ionisation energies decrease between group 5 and 6 elements?
electron being removed is from a paired electron in a p-orbital so is experiencing repulsion
(group 6 element)