Chapter 1 Atomic Structure Flashcards
What are the three subatomic particles and what are their charges?
protons- positive (+1/+1e)
neutrons- neutral
electrons- negative (-1/-1e)
e = 1.6x10-19C
Where are protons found, and what is their mass?
Protons are found in the nucleus, and they are approximately 1 AMU (atomic mass unit)
What does the atomic number of an element refer to? How does atomic number change between isotopes?
The atomic number of an element refers to the number of protons an element has.
Isotopes are elements with the same number of protons, but they vary in NEUTRONS, thus the atomic number does not change between isotopes.
What is an element’s mass number?
An element’s mass number is the sum of the protons and neutrons in an atom’s nucleus.
What are isotopes?
Isotopes are atoms that share an atomic number (number of protons) but have different mass numbers.
Number of neutrons varies between isotopes but the number of protons remains constant.
What does each letter represent?
X: atom/element
A: Mass number of atom X
Z: atomic number
Mass number v Atomic Number
Mass number: sum of protons and neutrons in an atom’s nucleus; varies between isotopes
Atomic number: sum of atom’s protons; constant between isotopes
Where do electrons move and what are they associated with?
Electrons move through the same surrounding the nucleus, and they are associated with varying levels of energy
How does the distance of an electron from the nucleus impact its energy level?
Electrons closer to the nucleus are at lower energy levels
Electrons that are farther from the nucleus are at higher energy levels.
What are valence electrons, and what are they more likely to do and why?
Valence electrons are electrons that are farthest from the nucleus. They have the strongest interactions with the surrounding environment and the weakest interactions with the nucleus.
Valence electrons are more likely to become involved in bonds with other atoms because they experience the least electrostatic pull from their own nucleus.
Losing electrons results in the atom gaining a ___ charge.
Gaining electrons results in the atom gaining a ___ charge.
Losing electrons results in the atom gaining a positive charge.
Gaining electrons results in the atom gaining a negative charge.
What is a cation?
What is an anion?
A cation is a positively charged atom.
An anion is a negatively charged atom.
Atomic mass v atomic weight
The atomic mass of an atom is nearly equal to its mass number (sum of protons and neutrons in an atom’s nucleus)
The atomic weight is the weighted average if different isotopes, and it is the number reported on the periodic table.
What is the Planck relation (equation), and what does it provide?
Planck relation: E = hf (where h = 6.626x10-34 J *s)
h = Planck’s constant; f is the frequency of radiation
This describes the energy of a quantum
Ground state v Excited State
Ground State of an atom: the state of lowest energy, in which all electrons are in the lowest possible orbital
Excited State: an atom is an excited state when at least one electron has moved to a subshell of higher than normal energy
What is the most significant difference between the Bohr Model and the Modern Quantum Mechanical Model
Bohr postulated that electrons follow a clearly defined circular pathway (orbit) at a fixed distance from the nucleus. Modern Quantum Mechanics shows that this is not the case; electrons are localized in orbitals (regions of space around the nucleus)
What does the Heinsenberg Uncertainty Principle state?
It is impossible to simultaneously determine, with perfect accuracy, the momentum and position of an electron
What are the four quantum numbers (in order)?
principal quantum number (denoted by n)
azimuthal (angular momentum) quantum number (denoted by l)
magnetic quantum number (denoted by ml)
spin quantum number (denoted by ms)
what does the Principal quantum number (n) describe
describes the average energy of a shell
can theoretically be any positive integer
the larger the integer value, the higher the energy level and radius of the electron’s shell
What is the maximum number of electrons within a shell?
2n2
where n is the principal quantum number
How is the difference in energy between two shells impacted as the distance from the nucleus increases?
The difference in energy between two shells decreases as the distance from the nucleus increases
What does the second quantum number refer to?
The second quantum number is the azimuthal (angular momentum) quantum number (l), and it refers to the shape and number of subshells within a given principal energy level (shell).
How does the value of n limit the value of l?
l = n-1
What is the spectroscopic notation for the azimuthal quantum numbers?
l=0 ⇒ s
l=1 ⇒ p
l=2 ⇒ d
l=3 ⇒ f
What subshell (using spectroscopic notation) is an electron in if it is in shell n=4 and subshell l =2?
the electron is in the 4d subshell
What does the third quantum number refer to?
The third quantum number is the magnetic quantum number (ml), and it specifies the particular orbital within a subshell where an electron is most likely to be found at a given moment in time
How does the value of the second quantum number impact the value of the third quantum number?
ml = values ranging from ±l (including 0)
How many orbitals are in the d subshell?
5
d = l=2
ml= -2, -1, 0, 1, 2
What are the shapes of the s orbitals and the p orbitals?
the two s orbitals are spherical
the three p orbitals are dumbbell shaped, and align along the x, y, and z axis
the three p orbitals are denoted by: 2px, 2py, 2pz
What is the fourth quantum number?
The fourth quantum number is the spin quantum number (ms), and its value is either +½ or -½
indicates spin orientation
what are paired electrons?
what are electrons with parallel spin?
paired electrons: electrons in the same orbital with opposite spins
parallel electrons: electrons in different orbitals with the same spin
What does the Pauli Exclusion Principal state?
No two electrons in a given atom can possess the same set of four quantum numbers
What is an electron’s energy level?
An electron’s energy level is the position and energy of an electron described by its quantum numbers
What does the Aufbau principle state?
Electrons fill from lower to higher energy level subshells, and each subshell will fill completely before electrons begin to enter the next one
What is the n+l rule used for?
It is used to rank subshells by increasing energy
Which subshell will fill first: the 5d subshell or the 6s subshell?
5d: d=2→ l=2; 5=n; 5+2=7
6s: s=0→l=0; 6=n; 6+0 =6
6s will fill first because it has a lower energy level
Which subshell will fill first: the 5d subshell or the 6s subshell?
5d: d=2→ l=2; 5=n; 5+2=7
6s: s=0→l=0; 6=n; 6+0 =6
6s will fill first because it has a lower energy level
What does Hund’s Rule state?
Orbitals fill according Hund’s rule
Hund’s rule states that there are a max number of half-filled orbitals with parallel spins
half-filled and fully filled orbitals have lower energies (and thus higher stabilities) than other states
What are the two exceptions for electron configuration (and give their electron configurations)?
Chromium: [Ar]4s13d5
Copper: [Ar]4s13d10
Paramagnetic materials v Diamagnetic materials
Paramagnetic: unpaired electrons present that align with magnetic fields, attracting the material to a magnet
diamagnetic: only paired electrons, which cannot easily be realigned, thus they are repelled by magnets
how does presence of unpaired or paired electrons impact magnetic properties of an atom/molecule?
materials composed of atoms with unpaired electrons will orient their spins in alignment with a magnetic field, and thus will be weakly attracted to the magnetic field
materials composed of atoms that only have paired electrons will be slightly repelled by a megnetic field
What are the valence electrons for groups 1, 2, and 13-18
valence electrons found in the s and/or p orbitals
where are the valence electrons found for transition elemenets?
valence electrons found in s and either d or f orbitals
