Chapter 3 The Atom Flashcards
What is the basic building block of all matter?
The atom
Atoms make up everything in the world, including visible and invisible substances.
How many different types of atoms are known as of the printing of this book?
118 different types
Some of these atoms are human-made and exist for a short time.
What is the Periodic Table?
A systematic way of arranging all atoms
Atoms are listed in increasing atomic number.
What do elements consist of?
Only one type of atom
Example: Oxygen is an element made up of only oxygen atoms.
What is a compound?
A substance made up of at least two different types of atoms combined
Example: Water is a compound made up of hydrogen and oxygen atoms.
True or False: Atoms change when they form compounds.
False
Atoms remain the same even when compounds are formed.
Fill in the blank: The atoms in the air you breathe in today could have been the same ones that ______.
people breathed in thousands of years ago
This illustrates the constancy of atoms over time.
What helps us understand the structure of atoms and the reactions of elements?
The organisation of the Periodic Table
The arrangement into rows and columns is crucial for understanding atomic behavior.
What is the relationship between atoms and compounds?
Atoms combine to make compounds
Compounds can break up and recombine, but the atoms themselves do not change.
What is a model in the context of science?
A representation of an object or system
What type of models are often used in science to show and explain scientific ideas?
Conceptual models
What was an example of a conceptual model mentioned in the previous chapter?
Kinetic molecular model of matter
What does the term ‘atomos’ mean in Greek?
‘Without cutting’ or ‘indivisible’
Who was the Greek scientist that proposed the idea of indivisible particles?
Democritus
What did John Dalton suggest about atoms in his atomic theory?
Matter is made up of indivisible particles called atoms
According to Dalton’s atomic theory, how do atoms of a particular element compare to atoms of other elements?
All atoms of a particular element are identical but differ from the atoms of other elements
What happens during a chemical change according to Dalton’s atomic theory?
The rearrangement of atoms in compounds, but the atoms remain intact
Fill in the blank: A model represents the current scientific understanding, and as ideas change, the _______ changes as well.
[model]
True or False: Dalton’s atomic theory states that all atoms are indivisible.
True
What did Davy, Faraday, and Berzelius discover about chemical compounds in the 1800s?
Chemical compounds are decomposed when an electrical current passes through them
This discovery indicated the electrical nature of matter.
Who proposed the name ‘electron’ for the unit of electrical charge?
Stoney
Stoney suggested that electricity consists of separate units or particles.
What did J.J. Thomson establish in 1897 regarding electrical discharge?
It is made up of very small, negatively charged particles known as electrons
These electrons were the particles predicted by Stoney.
What are protons and how do they relate to electrons?
Particles with a positive charge, equal in size to electrons but with a mass 1,836 times heavier
Protons neutralize the negative charge of electrons, making atoms overall neutral.
What was Thomson’s model of the atom?
The atom was made up of uniform positive charge with negative electrons embedded within it
This model is often likened to ‘currants in a currant bun’.
What was the significance of Henri Becquerel’s experiment with uranium in 1896?
It proved that uranium emitted radiation without an external energy source
This led to the discovery of radioactivity.
Who further investigated the phenomenon of radioactivity after Becquerel?
Pierre and Marie Curie
They named the phenomenon ‘radioactivity’ and discovered other radioactive elements.
Fill in the blank: The particles discovered by Thomson that are negatively charged are called _______.
electrons
True or False: Protons have a negative charge.
False
Protons have a positive charge.
What did Becquerel initially believe about the uranium compound and sunlight?
That it absorbed sunlight and emitted it as x-rays
This theory was disproved by his experimental results.
What was the mass comparison between protons and electrons?
Protons are 1,836 times heavier than electrons.
Who proposed the nuclear model of the atom?
Ernest Rutherford
Rutherford’s nuclear model was proposed in 1911.
What type of particles did Rutherford use in his experiments?
Positively charged alpha particles (a-particles)
These particles are emitted by radioactive elements.
What did Rutherford’s experiment involve bombarding?
Thin gold foil
This was a key part of the experimental setup.
What was the main finding regarding the alpha particles in Rutherford’s experiment?
Most passed through the gold foil, but a few were scattered at very large angles
This indicated the presence of a dense nucleus.
What did the scattering of a-particles suggest about the structure of the atom?
The existence of a dense nucleus
This was a significant departure from Thomson’s model.
True or False: Rutherford’s experiments confirmed Thomson’s model of the atom.
False
New experimental evidence showed Thomson’s model to be incorrect.
What did Rutherford conclude about the structure of an atom?
An atom must be almost completely empty space, with a very small, extremely dense nucleus at the center containing all the protons, and electrons in the remaining volume of the atom.
Rutherford’s model emphasized the nucleus’s density and the spatial distribution of electrons.
What is found at the center of an atom according to Rutherford’s model?
A very small, extremely dense nucleus containing all the protons.
The nucleus is positively charged due to the presence of protons.
What surrounds the nucleus in an atom?
Electrons in the remaining volume of the atom.
Electrons are negatively charged and are distributed around the nucleus.
What was one of the main unanswered questions in Rutherford’s model of the atom?
Why the negatively charged electrons did not simply spiral in towards the positively charged nucleus.
This question highlighted the limitations of Rutherford’s model and led to further developments in atomic theory.
True or False: Rutherford’s model explained all details of atomic structure.
False.
While it explained many aspects, it left significant questions unanswered.
Who produced a model of the atom in 1913?
Niels Bohr
Niels Bohr’s model was based on the work of other scientists like Albert Einstein and Max Planck.
What did Bohr’s model suggest about the electron in a hydrogen atom?
The electron could move in certain fixed orbits with specific energy levels
Electrons could only change orbits by absorbing or releasing energy.
What happens when an electron moves between energy orbits in Bohr’s model?
It absorbs or releases a fixed amount of energy
This energy corresponds to a specific frequency of light.
What type of spectrum is produced when an electric current is passed through hydrogen gas at low pressure?
A line spectrum
This indicates that hydrogen emits light of specific frequencies.
True or False: Bohr’s model worked well for all elements, not just hydrogen.
False
Bohr’s model was specifically effective for the hydrogen atom.
Fill in the blank: Bohr’s model helps explain the _______ produced by hydrogen gas.
line spectrum
The line spectrum corresponds to specific energy levels of the hydrogen atom.
Who produced a model of the atom in 1913?
Niels Bohr
Niels Bohr’s model was based on the work of other scientists like Albert Einstein and Max Planck.
What did Bohr’s model suggest about the electron in a hydrogen atom?
The electron could move in certain fixed orbits with specific energy levels
Electrons could only change orbits by absorbing or releasing energy.
What happens when an electron moves between energy orbits in Bohr’s model?
It absorbs or releases a fixed amount of energy
This energy corresponds to a specific frequency of light.
What type of spectrum is produced when an electric current is passed through hydrogen gas at low pressure?
A line spectrum
This indicates that hydrogen emits light of specific frequencies.
True or False: Bohr’s model worked well for all elements, not just hydrogen.
False
Bohr’s model was specifically effective for the hydrogen atom.
Fill in the blank: Bohr’s model helps explain the _______ produced by hydrogen gas.
line spectrum
The line spectrum corresponds to specific energy levels of the hydrogen atom.
What is the currently accepted model of the arrangement of electrons in atoms?
The wave mechanical model
This model incorporates the wave-particle duality of electrons.
Who proposed that light can be both a wave and a particle?
Albert Einstein
Einstein’s work laid the foundation for understanding wave-particle duality.
What year did Louis de Broglie propose that electrons have wave properties?
1924
De Broglie’s proposal was a significant advancement in quantum mechanics.
What is the uncertainty principle proposed by Werner Heisenberg?
It is impossible to know both the velocity and the position of an electron at the same time
This principle highlights limitations in measuring quantum particles.
How does the uncertainty principle conflict with the Bohr model?
The Bohr model assumes precise knowledge of both the energy and position of an electron
The Bohr model does not account for wave properties of electrons.
In what year did Erwin Schrödinger derive a mathematical wave equation?
1927
Schrödinger’s work was essential for the development of quantum mechanics.
What does the Schrödinger wave equation help calculate?
The energy levels in a hydrogen atom
This equation is fundamental to modern quantum mechanics.
What is defined as a region in which there is a high probability of finding an electron?
An orbital
Orbitals are key concepts in understanding electron configurations.
Who proposed the existence of neutrons?
Rutherford in 1920
Rutherford’s proposal preceded the actual discovery of neutrons.
Who discovered the neutron and in what year?
Chadwick in 1932
Chadwick’s discovery was pivotal in understanding atomic structure.
What did Lise Meitner and Otto Hahn demonstrate regarding uranium atoms?
Uranium atoms could be split by bombarding them with neutrons
This work contributed to the understanding of nuclear fission.
What significant development resulted from the work of Meitner and Hahn?
The production of the first atomic bomb
Their research laid the groundwork for nuclear weaponry.
What is a scientific model?
A representation of a scientific idea
Models help to conceptualize complex scientific phenomena.
Why are models often developed in science?
When it is difficult to experiment directly
Models allow scientists to theorize and predict outcomes.
How do investigations of the atom affect its behavior?
They probably change the behavior of the atom
This is a consideration in quantum mechanics and atomic studies.
Is a scientific model open to proof?
No, a model is not open to proof
Models are instead evaluated based on their predictive power and adaptability.
What happens to a scientific model as new discoveries are made?
The model is adapted to incorporate new knowledge
This iterative process is essential for scientific progress.
Fill in the blank: A model gives scientists a common way of thinking about the _______.
atom
Common understanding is crucial for collaboration and communication in science.
What is the approximate atomic mass of hydrogen?
0.00000000000000000000000000167 kg
This value shows the extremely small mass of hydrogen, the lightest element.
How many zeros are there before the digits 167 in the atomic mass of hydrogen when expressed in kilograms?
26 zeros
This highlights the minuscule scale of atomic mass.
What is the atomic mass of uranium when expressed in kilograms?
0.000000000000000000000000395 kg
Uranium is the heaviest natural element.
How many zeros are there before the digits 395 in the atomic mass of uranium?
24 zeros
This illustrates the small mass of even the heaviest natural element.
What is the range of diameters for atoms?
1 × 10^-10 m to 4 × 10^-10 m
This indicates the extremely small size of atoms.
According to Rutherford’s scattering experiment, what accounts for most of the mass of an atom?
The nucleus
The nucleus is located at the center of the atom.
True or False: Most of the volume of an atom is occupied by solid matter.
False
Most of the volume of an atom is empty space.
Fill in the blank: The average mass of hydrogen is approximately _______ kg.
0.00000000000000000000000000167
This emphasizes the incredibly small mass of hydrogen.
What element is considered the lightest?
Hydrogen
Hydrogen has the smallest atomic mass of all elements.
What is the significance of Rutherford’s scattering experiment in understanding atomic structure?
It revealed that most of an atom’s volume is empty space
This experiment contributed significantly to the modern atomic model.
What is relative atomic mass?
A measure of the mass of an atom relative to hydrogen, which has a mass of 1.
Why was hydrogen chosen as the standard for the atomic mass scale?
Because it is the lightest element.
What value is assigned to hydrogen on the atomic mass scale?
1
How is the relative atomic mass of other elements calculated?
By using proportions relative to hydrogen’s mass.
If hydrogen has a mass of 1.67355 × 10^-27 kg, what is the relative mass of oxygen with a mass of 2.65659 × 10^-26 kg on the hydrogen scale?
15.87
Fill in the blank: The incredibly small values of atomic masses led to a search for a more suitable _______.
scale
True or False: The relative atomic mass of an element can be determined independently of hydrogen’s mass.
False
List the steps to find the relative atomic mass of an element.
- Identify the mass of hydrogen
- Use the mass of the element
- Calculate using proportions
What is the significance of choosing a convenient standard mass in atomic mass calculations?
It simplifies the comparison of atomic masses between elements.
Why was hydrogen found unsuitable as a standard for atomic masses?
Hydrogen was replaced first by oxygen, and later by carbon-12.
What standard value was assigned to carbon-12?
12
What is necessary to understand the concept of carbon-12?
To find out more about the structure of an atom.
What are the three fundamental subatomic particles in an atom?
Protons, neutrons, electrons
Where are protons and neutrons located in an atom?
In the nucleus
What occupies the relatively large region around the nucleus of an atom?
Electrons
In a neutral atom, what is the relationship between the number of electrons and protons?
They are equal
What happens to the charge of an atom if an electron is removed?
It becomes positively charged
What is an ion?
An atom that has a charge on it
How does the size of an atom compare to the size of its nucleus?
About one hundred thousand times greater
What is the approximate diameter of an atomic nucleus?
10^-15 m
What analogy is used to compare the size of a nucleus to the size of an atom?
A tennis ball in the center of a football field
What is the density of the nucleus relative to the overall atom?
Very dense
What comprises almost all the mass of an atom?
The nucleus
Fill in the blank: An atom’s nucleus is very small, but also very _______.
Dense
True or False: Electrons are located in the nucleus of an atom.
False
What is the atomic number?
The number of protons in the nucleus of an atom
The atomic number is symbolized by Z.
What does the mass number represent?
The sum of protons and neutrons in an atom
The mass number is also known as the nucleon number and is symbolized by A.
How is the number of neutrons in an atom calculated?
A minus Z
A represents the mass number and Z represents the atomic number.
True or False: All atoms of a particular element have the same number of neutrons.
False
Atoms of the same element can have different numbers of neutrons, leading to isotopes.
Fill in the blank: The atomic number is given the symbol _______.
Z
The atomic number uniquely identifies an element.
Fill in the blank: The mass number is given the symbol _______.
A
The mass number is crucial for understanding the composition of an atom.
What is the atomic number?
The number of protons in the nucleus of an atom
The atomic number is symbolized by Z.
What does the mass number represent?
The sum of protons and neutrons in an atom
The mass number is also known as the nucleon number and is symbolized by A.
How is the number of neutrons in an atom calculated?
A minus Z
A represents the mass number and Z represents the atomic number.
True or False: All atoms of a particular element have the same number of neutrons.
False
Atoms of the same element can have different numbers of neutrons, leading to isotopes.
Fill in the blank: The atomic number is given the symbol _______.
Z
The atomic number uniquely identifies an element.
Fill in the blank: The mass number is given the symbol _______.
A
The mass number is crucial for understanding the composition of an atom.
What defines isotopes of an element?
Isotopes of an element are defined by having the same atomic number but different numbers of neutrons.
How do isotopes differ from each other?
Isotopes differ in their mass numbers and atomic masses.
What is the atomic number of carbon?
The atomic number of carbon is 6.
What are the main isotopes of carbon?
The main isotopes of carbon are carbon-12 and carbon-13.
What is the mass number of carbon-12?
The mass number of carbon-12 is 12.
What is the mass number of carbon-13?
The mass number of carbon-13 is 13.
How do you calculate the number of neutrons in an atom?
The number of neutrons can be calculated using the formula A - Z.
Fill in the blank: The number of neutrons in a carbon-12 atom equals _______.
6
Fill in the blank: The number of neutrons in a carbon-13 atom equals _______.
7
True or False: Most elements exist in nature as a mixture of isotopes.
True
What are the three fundamental subatomic particles?
Protons, neutrons, electrons
What does the term ‘continuous spectrum’ refer to?
The spread of colors seen when white light is refracted through a prism
What is the speed of electromagnetic radiation in a vacuum?
c = 3.00 x 10^8 m•s
How is the energy of electromagnetic radiation related to its frequency?
Energy is proportional to frequency
What is the visible part of the electromagnetic spectrum characterized by?
Different colors corresponding to different frequencies
What color flame is produced when lithium reacts with oxygen?
Scarlet flame
What color flame is produced when sodium reacts with oxygen?
Yellow-orange flame
What color flame is produced when potassium reacts with oxygen?
Lilac flame
Why are flame tests useful for identifying Group 1 metals?
Each element produces a specific flame color
What happens to an electron when it is ‘excited’ by heating?
It moves to a higher energy level
What occurs when an excited electron drops back to its normal energy level?
It emits energy in the form of light
Fill in the blank: The energy between electron levels is _____ for different types of atoms.
different
True or False: The flame color produced during a reaction is the same for all elements.
False
What did Bohr propose about electrons in atoms?
Bohr proposed that it is possible to excite the electrons of a particular type of atom to a number of different energy levels.
This concept is fundamental to understanding atomic structure and the behavior of elements.
What is the significance of line emission spectra?
Line emission spectra are significant because they illustrate the specific wavelengths of light emitted by electrons transitioning between energy levels in an atom.
Each element has a unique emission spectrum, which can be used for identification.
Fill in the blank: Bohr’s model is primarily concerned with the _______ of electrons.
[energy levels]
True or False: Line emission spectra are the same for all elements.
False
Each element has a distinct line emission spectrum based on its unique electron configuration.
What does the excitation of electrons lead to in terms of light emission?
It leads to the emission of light at specific wavelengths when electrons transition back to lower energy levels.
This process is responsible for the characteristic colors observed in different elements.
What do atoms emit when heated or subjected to electric discharges?
Line emission spectra
Each set of frequencies corresponds to a particular type of atom.
What is produced when the light emitted from heated hydrogen gas is passed through focusing slits and refracted by a prism?
A line spectrum
This spectrum shows an uneven pattern of lines of different colors.
What does each line in a line emission spectrum indicate?
One particular frequency being emitted
The lines correspond to specific frequencies of light.
What is the Balmer series associated with?
Visible range frequencies emitted by hydrogen
It is one of the sets of frequencies that can be observed.
What is an example of a series that emits frequencies in the ultra-violet range?
Lyman series
This series is not visible to the human eye.
True or False: All emitted frequencies from atoms are in the visible range.
False
Atoms can emit frequencies that are not visible, such as in the Lyman series.
Fill in the blank: The set of frequencies emitted by atoms produces _______ when gases are heated.
Line emission spectra
This phenomenon occurs due to the excitation of electrons.
What corresponds to light of a definite frequency in a line spectrum?
Each colored line
The colors represent specific frequencies emitted by the atom.
Who proposed the explanation for the line spectrum of hydrogen in 1913?
Niels Bohr
Bohr’s proposal laid the foundation for modern atomic theory.
What is the concept of energy quantisation in relation to electrons in hydrogen atoms?
Electrons have fixed energy values
This means that electrons can only occupy certain energy levels or stationary states.
What are the fixed energy levels that electrons can occupy in hydrogen atoms called?
Stationary states
Electrons can transition between these states by absorbing or emitting energy.
What must occur for an electron to move from one energy level to another?
Absorb or emit fixed amounts of energy
The energy change must equal the difference between the two levels.
How can energy levels in hydrogen atoms be visualized?
Like a set of steps
Electrons can only occupy certain steps, representing quantized energy levels.
What analogy is used to describe how electrons lose energy when moving to lower energy levels?
A ball rolling down steps
The ball loses potential energy in fixed amounts corresponding to the height of each step.
What is the relationship between energy (E) and frequency (f) according to Planck’s equation?
E = hf
In this equation, h is Planck’s constant.
What is the value of Planck’s constant (h)?
6.63 × 10^-34 J•S
This constant relates energy and frequency in quantum mechanics.
True or False: Electrons can occupy any energy level continuously.
False
Electrons can only occupy specific, quantized energy levels.
Fill in the blank: The concept of quantisation of energy was put forward by _______.
Max Planck
Planck’s work in quantum theory laid the groundwork for Bohr’s model.
What phenomenon did Bohr’s proposal account for?
The line emission spectrum of hydrogen
This spectrum is a series of specific wavelengths of light emitted by hydrogen when electrons transition between energy levels.
What happens when electrons move from higher to lower energy levels in hydrogen atoms?
Energy is emitted as light of a particular frequency
This emission corresponds to specific wavelengths in the hydrogen spectrum.
How are the energy levels in hydrogen atoms labeled according to Bohr’s model?
They are labeled as n = 1, n = 2, and so on
The variable n represents quantum numbers.
What are the values for n in Bohr’s model called?
Quantum numbers
Quantum numbers indicate the discrete energy levels of electrons in an atom.
True or False: Bohr’s model suggests that energy is emitted continuously.
False
Energy is emitted in discrete quantities corresponding to specific frequency transitions.
Fill in the blank: The transitions of electrons between energy levels in hydrogen are illustrated in _______.
Figure 3.11
This figure visually represents the concept of electron transitions and energy levels.
What does an energy level diagram illustrate in relation to the energy of electrons in a hydrogen atom?
The energy of the electron can only change by fixed amounts
This means that electrons can only occupy specific energy levels.
What do the upward arrows in the energy level diagram represent?
Electrons absorbing fixed amounts of energy to move from lower to higher energy levels
This indicates that energy absorption is quantized.
What do the downward arrows in the energy level diagram indicate?
Fixed amounts of energy are released as light of particular frequencies when electrons move from higher to lower energy levels
This process is known as emission.
Fill in the blank: Electrons can only absorb or emit energy in _______ amounts.
fixed
True or False: Electrons in a hydrogen atom can exist at any energy level.
False
Electrons can only exist in specific, quantized energy levels.
What does an energy level diagram illustrate in relation to the energy of electrons in a hydrogen atom?
The energy of the electron can only change by fixed amounts
This means that electrons can only occupy specific energy levels.
What do the upward arrows in the energy level diagram represent?
Electrons absorbing fixed amounts of energy to move from lower to higher energy levels
This indicates that energy absorption is quantized.
What do the downward arrows in the energy level diagram indicate?
Fixed amounts of energy are released as light of particular frequencies when electrons move from higher to lower energy levels
This process is known as emission.
Fill in the blank: Electrons can only absorb or emit energy in _______ amounts.
fixed
True or False: Electrons in a hydrogen atom can exist at any energy level.
False
Electrons can only exist in specific, quantized energy levels.
What are quantum numbers?
They are numbers that describe the energy levels of electrons in atoms
Originally referred to by Bohr for different energy levels.
What is the principal quantum number?
It is the number originally used by Bohr to denote different energy levels
It indicates the relative distance of the electron from the nucleus.
What is the principal quantum number for the lowest energy level?
n = 1
This level is closest to the nucleus of the atom.
What is the principal quantum number for the second lowest energy level?
n = 2
This level is further from the nucleus than n = 1.
True or False: The principal quantum number can only be a positive integer.
True
Quantum numbers are always positive integers.
Fill in the blank: The principal quantum number for the third energy level is _______.
n = 3
This continues the pattern of increasing energy levels.
What did Bohr’s proposals regarding quantum numbers help explain?
The existence of many more lines in atomic spectra
This indicated that there are numerous possible energy states for electrons.
What are quantum numbers?
They are numbers that describe the energy levels of electrons in atoms
Originally referred to by Bohr for different energy levels.
What is the principal quantum number?
It is the number originally used by Bohr to denote different energy levels
It indicates the relative distance of the electron from the nucleus.
What is the principal quantum number for the lowest energy level?
n = 1
This level is closest to the nucleus of the atom.
What is the principal quantum number for the second lowest energy level?
n = 2
This level is further from the nucleus than n = 1.
True or False: The principal quantum number can only be a positive integer.
True
Quantum numbers are always positive integers.
Fill in the blank: The principal quantum number for the third energy level is _______.
n = 3
This continues the pattern of increasing energy levels.
What did Bohr’s proposals regarding quantum numbers help explain?
The existence of many more lines in atomic spectra
This indicated that there are numerous possible energy states for electrons.
What is the arrangement of electrons in an atom called?
Electron configuration
This includes core and valence electrons.
In the wave mechanical model of the atom, what dual properties do electrons exhibit?
Waves and particles
This duality means their exact position cannot be determined.
What term describes the probability of finding an electron within a region of space around the nucleus?
Orbital
Orbitals represent areas where electrons are likely to be found.
What are the energy levels of an atom defined by?
Principal quantum numbers (n)
These numbers can be 1, 2, 3, etc.
How are the number of subshells and types of orbitals related to principal quantum numbers?
They are equal to the principal quantum number
For example, for n=1, there is 1 subshell; for n=2, there are 2 subshells.
Fill in the blank: The arrangement of electrons into _______ and valence electrons.
Core electrons
True or False: It is possible to know the exact location of an electron at any given time.
False
Due to the probabilistic nature of quantum mechanics, only the likelihood of finding an electron can be determined.
What defines the structure of energy levels in an atom?
Subshells and orbitals
These are organized according to principal quantum numbers.
What is the electron configuration of an atom?
The arrangement of the electrons around the nucleus of an atom.
It normally applies to an atom in its ground state.
What does ground state mean in terms of electron configuration?
The state in which electrons occupy the lowest possible energy levels.
This is the most stable state of an atom.
What principle is used to find the ground state electron configuration of an element?
The Aufbau principle.
‘Aufbau’ means ‘building up’ in German.
What does the Aufbau principle state?
Electrons occupy atomic orbitals in order of increasing energy.
This principle guides how electrons fill up orbitals.
What is required to understand how electrons fill up atomic orbitals?
Knowledge of the energy order of the orbitals.
This is essential for determining the correct electron configuration.
