Topic 1: Atomic structure and the Periodic Table Flashcards
Define Relative Atomic Mass
weighted mean of the atoms of a normal sample relative to the 1/12th the mass of the c-12 isotope.
Define Relative Isotopic Mass
mass of an isotope of the element relative to 1/12th the mass of the C-12 isotope
Define Relative Molecular Mass
mass of a molecule relative to 1/12th the mass of the C-12 isotope
Main processes involved in mass spectrometry
1) The sample is vaporised
2) The sample is ionised
3) the ions are accelerated by an electric field
4) the accelerated ions pass through a magnetic field and are deflected
5) the ions are detected and recorded
Define First Ionisation Energy
The energy required to remove one electron from each atom in one mole of gaseous atoms producing one mole of gaseous ions with one positive charge.
General Trend for First Ionisation energies
going across a period, ionisation energy increases.
going down groups, ionisation energy decreases.
Define Second Ionisation energy
The energy required to remove one electron from each ion in one mole of gaseous ions with a single positive charge producing one mole of gaseous ions with two positive charges.
Electronic Configuration of Copper
1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^1, 3d^10
Electronic configuration of Chromium
1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^1, 3d^5
Evidence for electron shells and subshells
successive ionisation energies provide evidence for the existence of electron shells.
first ionisation energies provide evidence for the existence of electron subshells.
Relative Atomic Mass Equation
(mass x abundance) / 100
The table below gives information on the heights of peaks in a mass spectrum of chromium. M/z Height of peak in cm 50 0.4 52 8.0 53 0.9 54 0.2
A) Calculate the percentage abundance of each isotope to one decimal place
B) Calculate the relative atomic mass of chromium to 2 dp.
a) 0.4+8+0.9+0.2=9.5
abundances: 4.2, 84.2, 9.5, 2.1
b) answer= 52.05
Explain why successive ionisation energies increase
.After each ionisation the positive charge on the ion increases
.So to remove the next electron, more energy is required to overcome this greater attraction
There is a general increase in first ionisation energy from Na to Ar. Explain this trend
.Same electron shell
.Same distance from nucleus
.Nuclear charge increases so attraction to the nucleus from the outer electron increases
Explain why in group 1 of the periodic table, the first ionisation energy decreases down the group.
Atoms become larger
electrons further away from the nucleus
more shielding electrons
Define Orbital
the region in an atom which can hold up to 2 electrons with opposite spins
The diagram below shows the visible line spectrum of hydrogen
a) What quantity is representing along the horizontal axis
b) Is this quantity increasing or decreasing from left to right
c) Explain why the atomic spectrum consists of a series of lines
d) To which energy level do the transitions corresponding to the visible lines in the spectrum of hydrogen relate
a) energy
b) decreasing
c) an excited electron drops back down from various higher energy shells to a lower energy shell
d) electrons dropping down to shell 2
Explain why the second ionisation energy of each element is higher than the corresponding first ionisation energy
electron removed
positive charge
increased attraction
more energy required
Why do the maxima of the second ionisation energies occur at sodium and potassium
Sodium and potassium have one electron in the outer shell
to remove a second electron requires breaking in to a full inner shell
more energy required to break into inner shell
explain why the first ionisation energy of magnesium is greater than that of aluminium
Although nuclear charge of Al is greater
last electron added to Al goes into 3p subshell
extra shielding
more energy needed
explain why the melting temperatures increase from sodium to aluminium
positive charge on the metal ion increases
greater charge density
number of electrons in the delocalised electron region increases
attraction between ions and the delocalised electrons increases
more energy required
write an equation to represent the first ionisation energy of O.
O(g) -> O⁺(g) + e⁻
define the term periodic as applied to elements of the periodic table
patterns in properties
repeat across different periods
