Atomic Structure Flashcards
How do you calculate the electron configuration of a substance?
Go from the noble gas, it will represent full subshells at a particular level then count from there.
How do find the highest oxidation state of a substance?
Look at the successive ionisation energy graph, where there is a jump shows the end of the 1st subshell.
What are the names of the 6 steps in using a mass spectrometer?
Vacumn, Ionisation, acceleration, ion drift, detection and data analysis.
Why must the whole mass spectrometer be kept in a vacuum?
This is to prevent the ions formed in the apparatus from colliding with molecules in the air
Name one method of ionisation used in mass spectrometry.
The sample is first dissolved in a volatile solvent and then forced through an electrically charged hollow needle to produce a stream of positively charged ions. They may also use an electron gun to knock off electrons leaving only positively charged ions.
What happens at the acceleration stage?
The ions are accelerated so they all have the same kinetic energy and drift towards the negatively charged plate via electrostatic attraction.
What happens at the ion drift stage?
The positive ions pass through a hole in the plate, They then form a beam that travels through the flight tube.
What happens at the detection stage?
The ions reach the detector are recorded, based on how long it takes for them to reach the detector. The lighter the ions the less time it takes for them to reach the detector.
What are the general trends for the first ionisation energies of elements in a group?
The first ionisation energy decreases due to increased shielding and distance from the nucleus.
Describe the evidence to show the existence of energy levels.
Successive ionisations provide evidence for the existence of energy levels as when electrons which would exist in different subshells are extracted there is a large difference in the energy required to do this. In addition across a period, the first ionisation energy levels also vary due to the electrons being extracted from different subshells.
Describe the trend in the ionisation energies in period 3.
There is an increase in the force of attraction across the period as the number of protons increase, the number of electrons also increase but as they mostly go in the same energy level, the first ionisation energies in general increase.
What are the exceptions to the trend described in period 3 and why?
Between Magnesium and Aluminium = Aluminium outer electron is in the 3p sublevel which is a slightly higher energy level and thus is easier to remove leading to a decrease in ionisation energy. Between Phosphorus and Sulfur: In sulfur to p electrons are paired, they repel each other and are thus easier to remove.
Who proposed that some substances could not be made simpler? and when did he do so?
1661- Robert Doyle
Who stated that elements were made of indivisible atoms and when?
1803 - John Dalton
Who discovered radioactivity and when?
1896- Henri Becquerel
Who discovered the electron and when?
1897- JJ Thomson
Who disproved the plum pudding model and discovered the nucleus and when?
1911- Ernest Rutherford
What is the mass of a proton?
1.673x10-27
What is the mass of a neutron?
1.675x10-27
What is the mass of an electron?
0.911x10-30
What is the magnitude of charge on an electron/proton?
1.602x10-19C
What are the relative masses of a proton: neutron: electron?
1 : 1 : 1/1840
What force holds together the nucleus i.e. protons and neutrons?
The strong nuclear force
What is the diameter of a hydrogen nucleus and what is the diameter of the atom itself.
2x10-15 and 1x10-10
What is another term for the atomic number?
Proton number Z
What is the total number of protons and neutrons represented by?
Mass number A
What is the definition of the term isotope?
Same number of protons, a different number of neutrons
How does carbon dating work?
There is a fixed proportion of carbon 14 which remains constant as living matter takes in and gives out carbon in the form of food and CO2. When an organism dies these processes stop and the carbon 14 begins to decay. Since the half-life of carbon 14 is known,i.e. 5730 years it is used to date the age of a living organism.
Who introduced radiocarbon dating and when?
Describe the reaction which introduces carbon 14 into the atmosphere?
1949- Willard Libby who won a Nobel Prize for the technique
147N+10n ->146C +11p
Who first proposed an atom consisted of a positive nucleus orbited by negatively charged electrons, like a small solar system? and when?
1913- Niels Bohr
Who worked out an equation that used the idea that electrons exhibited wave-particle duality?
1926 - Edwin Schrodinger
Who discovered the neutron? and when?
1932- James Chadwick
Who proposed 3 key ideas about how atoms bond together via electrons?
What were the ideas?
Gilbert Lewis
He proposed:
- The inertness of the noble gases was due to their full outer shells of electrons
- ions were formed by atoms losing or gaining electrons to attain full outer shells
- atoms could also bond by sharing electrons to form full outer shells.
What are the 6 key features/process in a mass spectrometer?
- Vacumn
- Ionisation
- Acceleration
- Ion Drift
- Detection
- Data Analysis
What is the definition of relative atomic mass?
The average mass of an atom relative to 1/12 of the mass of a carbon-12 atom
