Atomic Orbitals & Electron Structure Flashcards
What does VSEPR stand for?
Valence Shell Electron Pair Repulsion
VSEPR theory is used to predict the geometry of individual molecules.
What does the first law of thermodynamics state?
Work, heat, internal energy, enthalpy, and Hess’s law
It emphasizes the conservation of energy in chemical reactions.
What is entropy associated with in thermodynamics?
The Second Law of Thermodynamics
Entropy is a measure of disorder in a system.
What is Gibbs energy used to determine?
Chemical equilibrium, equilibrium constant, reaction quotient
It helps predict the spontaneity of a reaction.
What are the types of orbitals mentioned?
- s
- p
- d
- f
Each type of orbital has distinct shapes and energy levels.
What was Dalton’s classical atomic theory?
- elements are made of tiny identical particles called atoms
- atoms of different elements combine in whole-number ratios to make chemical compounds
- in chemical reactions, atoms are combined or separated or rearranged
What did Thomson discover?
The electron
He identified subatomic particles through cathode ray experiments.
What was Rutherford’s key discovery?
The nucleus
His gold foil experiment showed that atoms have a dense central nucleus.
What is Bohr’s model of the atom known for?
Quantization of energy levels
It proposed fixed orbits for electrons around the nucleus.
What principle did Heisenberg introduce?
It is impossible to know both the velocity and exact position of a particle simultaneously
It is only possible to measure the probability of finding an electron in a given volume of space
Fill in the blank: The energy of a photon is proportional to its _______.
frequency
This relationship is described by Einstein’s photoelectric effect.
What does the wavefunction (Ψ) represent?
The probability of finding an electron in a specific area of 3-dimensional space
It is a fundamental concept in quantum mechanics.
What characterizes the Principal Quantum Number (n)?
Describes the energy level
Will be a positive value = 1, 2, 3 etc
It indicates the shell in which an electron resides.
What is the significance of quantum numbers?
They describe the energy and shape of orbitals
Each orbital is defined by a unique set of quantum numbers.
What are the three quantum numbers used to describe an orbital?
- Principal Quantum Number (n)
- Orbital Angular Momentum Number (l)
- Magnetic Quantum Number (ml)
True or False: The 1s orbital is a spherical shape.
True
The 1s orbital is symmetric around the nucleus.
What causes the Coulomb potential energy of an electron to become more negative?
Decreasing distance from the nucleus
This reflects the increasing electrostatic attraction between the electron and nucleus.
What does the term ‘degeneracy’ refer to in orbitals?
Orbitals with the same quantum number (n) having the same energy
Degeneracy is only observed in hydrogen atoms.
What do radial nodes indicate in atomic orbitals?
Areas where there is zero probability of finding an electron
Radial nodes appear in the probability density plots of orbitals.
What is the probability of finding an electron in a 3s orbital close to the nucleus?
There is a high probability of finding an electron in a symmetrical sphere close to the nucleus
The probability density decreases sharply as we move further from the nucleus.
What happens to the probability density as we move further from the nucleus in a 3s orbital?
The probability density decreases sharply and reaches a radial node, then increases again further out
A radial node is an area where there is zero probability of finding an electron.
How many radial nodes does the 3s orbital have?
Two radial nodes
What distinguishes p orbitals from s orbitals?
P orbitals have a dependence on angular momentum and are not spherically symmetrical
They consist of a radial part and an angular part.
What are the lobes in a p orbital?
Each p orbital has a positive part and a negative part arranged along an axis, each called a lobe.
What is a nodal plane?
An area of zero probability of finding an electron in the space between the two lobes of a p orbital.
How do the 3p orbitals compare to 2p orbitals?
The 3p orbitals lie along the x, y, and z axes and have radial nodes that cut each lobe in half.
What is the significance of electron spin?
Electrons have spin, which is a type of angular momentum, either +1/2 or -1/2.
This is ‘ms’
What does the Aufbau Principle state?
Electrons fill the orbitals one electron at a time starting with the lowest energy state orbital.
Added in order of increasing values of (n+l) or subshell with lowest ‘n’ value
What is Hund’s Rule?
When electrons are added to states of the same energy, a single electron enters each state before a second electron enters any state.
Electrons are alone before they pair
What does the Pauli Exclusion Principle state?
No two electrons can have all four quantum numbers the same.
Must have opposite spin
How does electron-electron repulsion affect multi-electron atoms?
Electron-electron repulsion increases potential energy, while attraction to the nucleus lowers it.
Higher ‘n’ means stronger attraction and decreased distance
What happens to the size of orbitals in multi-electron atoms compared to hydrogen?
Orbitals are lower in energy and different in size due to higher positive charge in the nucleus.
What is the effective nuclear charge (Z_eff)?
The reduction of the true nuclear charge due to electron shielding.
What trend is observed in atomic radius as you go down a group?
Atomic radius increases due to a greater number of completed shells.
What trend is observed in atomic radius as you move from left to right across a period?
Atomic radius decreases due to increasing effective nuclear charge attracting electrons more strongly.
What happens to the size of an atom when it gains an electron?
It becomes larger than the parent atom.
What happens to the size of an atom when it loses an electron?
It becomes smaller than the parent atom.
What is ionization energy?
The energy required to remove an electron from an atom.
What is the trend in ionization energy as you go across a period?
Ionization energy increases due to increasing nuclear charge.
What is the trend in ionization energy as you go down a group?
Ionization energy decreases because the distance from the nucleus increases.
What is electronegativity?
The ability of an atom to attract an electron when it is part of a compound.
How does electronegativity change across a period?
Electronegativity increases as you go across a period.
How does electronegativity change down a group?
Electronegativity decreases as you go down a group.
What did De Broglie discover?
Particles exhibit both particle and wave properties which related wavelength to particle mass
λ = h/mv
What is quantum mechanics?
Describes the behaviour of atoms and molecules and their electrons
Energy is quantised into discrete packets (energy levels), it is not continuous
What does quantum mechanics show?
- Energy of a particle is quantised - can only take specific values
- We can only state the probability that a particle will be at a certain position
- A particle has a wavefunction (Ψ) associated with it which specifies its energy and probability of being in a specific location
What are the characteristics of the 1s atomic orbital?
- Lowest energy wavefunction
- Depends only on distance (r) between the electron and nucleus
- Has spherical symmetry
What is the Orbital Angular Momentum Number (l)?
Determines angular momentum and designates the subshell (shape of orbital(
Values 0 to (n-1)
What is the Magnetic Quantum Number (ml)?
Related to (l)
Designates the orbital orientation
Ranges from -l to +l
What is the 2s atomic orbital characterised by?
- High probability of finding an electron in a symmetrical sphere close to the nucleus
- Probability density decreases as we move farther away from the nucleus and reaches a radial node (zero probability here)
What is the guiding principle?
To keep total energy as low as possible
