atomic structure Flashcards
What are the three subatomic particles found in an atom?
Protons, neutrons, electrons
Where are electrons found in an atom?
Surrounding the nucleus in orbitals
What is the nucleus made of?
Protons and neutrons (nucleons)
What force holds protons and neutrons together in the nucleus?
Strong nuclear force
What type of force holds electrons in an atom?
Electrostatic forces
Who proposed the solid sphere model of the atom?
John Dalton
What model did J.J. Thomson create?
Plum pudding model
What experiment did Ernest Rutherford conduct?
Alpha scattering gold foil experiment
What did Rutherford’s experiment reveal about the atom?
Most of the atom is empty space
Who adapted the nuclear model to include electron shells?
Niels Bohr
What is mass number [A]?
Total number of protons + neutrons in the nucleus
What is atomic number [Z]?
The number of protons in the nucleus
What does relative atomic mass [A_r] represent?
Average mass of an atom of an element relative to 1/12 the mass of carbon-12
What is an isotope?
An atom of the same element with the same number of protons but a different number of neutrons
What is the significance of half-life in radioactive isotopes?
It measures the time it takes for half of its radioactivity to decay
What is a time of flight mass spectrometer (TOFMS) used for?
Determining relative isotopic masses and relative abundances
What is the first stage of TOFMS?
Ionisation
What ionisation method is used for low molecular mass compounds?
Electron impact ionisation
What ionisation method is used for high molecular mass compounds?
Electrospray ionisation
What happens during the acceleration stage of TOFMS?
Ions are accelerated using an electric field
What occurs in the ion drift stage of TOFMS?
Ions pass through a hole into a flight tube where they drift towards the detector
What does the mass spectrum of an element show?
Mass:charge ratio and relative % abundance of each isotope
What is the main peak in a mass spectrum?
The molecular mass [M_r] of the compound
What is the significance of the peaks at higher m/z ratios?
They represent isotopes
What is the effect of fragmentation in mass spectrometry?
Molecular ions break into smaller particles
What is the electron configuration for Chromium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵
What is the electron configuration for Copper?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d¹⁰
What is the first ionisation energy?
The energy needed to remove 1 electron from each atom of an element in one mole of gaseous atoms
What factors affect ionisation energy?
Atomic radius, nuclear charge, electron shielding
Fill in the blank: The _______ is the energy needed to remove 1 electron from each ion of an element in 1 mole of gaseous +1 ions.
Second ionisation energy
True or False: Electrons fill orbitals singly before they start sharing.
True
What is ionisation energy?
The energy needed to remove 1 electron from each atom of an element in one mole of gaseous atoms to form one mole of gaseous ions with a 1+ charge.
Ionisation energy is a key concept in understanding how atoms interact with energy and other atoms.
What is second ionisation energy?
The energy needed to remove 1 electron from each ion of an element in 1 mole of gaseous +1 ions to form 1 mole of gaseous ions with a +2 charge.
This concept illustrates the increasing energy required to remove additional electrons from an atom.
How does atomic radius affect ionisation energy?
The smaller the atomic radius, the higher the first ionisation energy.
This is due to the outer electron being more strongly attracted to the nucleus in smaller atoms.
What is the relationship between nuclear charge and ionisation energy?
The higher the nuclear charge, the higher the first ionisation energy.
A higher nuclear charge results in a smaller atomic radius and a stronger attraction of outer electrons to the nucleus.
How does shielding affect ionisation energy?
The more shielding, the lower the first ionisation energy.
Inner shells repel outer electrons, making them easier to lose.
What trend occurs in ionisation energy across a period?
Ionisation energy increases across a period due to higher nuclear charge and smaller atomic radius.
Outer electrons are more attracted to the nucleus while shielding remains constant.
What trend occurs in ionisation energy down a group?
Ionisation energy decreases down a group due to larger atomic radius and increased shielding.
Outer electrons are less attracted to the nucleus, making them easier to lose.
What is an exception to the ionisation energy trend between groups 2 and 3?
There is a dip in first ionisation energy due to moving to a new energy level with higher energy.
The S to P subshell transition results in electrons being further away from the nucleus and more shielding.
What is an exception to the ionisation energy trend between groups 5 and 6?
There is a dip in first ionisation energy due to electron repulsion in the p subshell.
In group 5, each orbital has one electron; in group 6, one orbital has two electrons, causing repulsion.
What are successive ionisation energies?
Successive ionisation energies refer to the increasing energy required to remove more electrons from an increasingly positive ion.
Each electron removed leads to a stronger attraction to the nucleus.
How do successive ionisation energies increase between shells?
There is a sudden rise in ionisation energy each time a new shell is broken into.
For example, sodium shows a significant jump in ionisation energy from the first to the second electron.
How do successive ionisation energies increase within each shell?
Ionisation energy increases because each electron removed is from an increasingly positive ion.
For magnesium, the second ionisation energy is greater than the first due to stronger attraction after the first electron is removed.
What evidence supports shell structure in atoms?
A sudden jump in ionisation energy indicates that another shell has been entered.
The drop in ionisation energy between group 2 and 3 suggests the presence of subshells.
