Atomic Structure Flashcards
Definitions, history of the atom, electron configuration and orbitals.
Define elements
The simplest substances, made up from simple particles.
Consist of atoms which are all the same (as single atoms, He, or bonded together, O2).
Define molecules
More than one atom bonded together (can be the same/different).
Define compounds
Combinations of different types of atom e.g. CO2.
Pure = two or more elements chemically combined.
Define pure substance
Made of only one type of particle.
Define atom
The smallest part of an element that can exist chemically (but not the smallest particles).
Define atomic number
The number of protons in the nucleus of an atom.
Define relative atomic mass
The sum of the number of protons plus neutrons in the nucleus of an atom.
Define isotope
Atoms of the same element with different numbers of neutrons.
Define a mole
Mass of a substance containing 6 x 10^23 atoms (or particles).
Define electron, what is strange about them?
Subatomic particles with an electric charge of -1.
Demonstrate wave particle duality.
Define atomic orbital
Region around an atom in which there is a high probability of finding an electron/pair of electrons.
Region of space defined by a wavefunction.
What did John Dalton propose in 1803?
The solid sphere model.
Based on the Ancient Greek idea that atoms are indivisible.
Atoms of a given element are identical.
(Compounds = combinations of different types of atoms).
What did J.J Thomson propose in 1904?
Plum pudding model.
After his discovery of electrons in 1897.
Atom composed of electrons scattered throughout a spherical cloud of positive charge.
What did Ernest Rutherford propose in 1911?
Nuclear model.
Fired positive alpha particles at gold foil, only some deflected at large angles (most passed through with little deflection).
Concluded atom mostly empty space with positive charge concentrated in central nucleus.
What did Niels Bohr propose in 1913?
Planetary model.
Electrons moved around nucleus in orbits of fixed sizes and energies but electron energy quantised (limited to specific energy values).
What did Erwin Schrodinger propose in 1926?
Quantum model.
Electrons move in waves, impossible to know exact locations of electrons but have clouds of probability = orbitals where electrons are likely to be found.
What do atoms of the same element have in common?
All have the same number of protons in their nucleus (atomic number).
Give the symbols for protons, neutrons and electrons.
p, n , e
Give the masses of p, n and e.
p = 1.673 x 10^-27 kg
n = 1.675 x 10^-27kg
e = 9.109 x 10^-31kg
Give the charges of p, n and e.
p = +1
n = 0
e = -1
Why are moles used?
A mole of atoms is easier to weigh compared to a single atom.
In terms of moles what does relative atomic mass report on?
The mass of a mole of atoms e.g. 6 x 10^23 carbon atoms weigh 12.011g
Give units for relative atomic mass (solids and liquids).
gmol^-1
molL^-1
What did Schrödinger suggest the behaviour of electrons in atoms could be explained by?
Properties of waves.
What is a wavefunction?
Describes electrons in particular orbit.
An equation to model movement of an electron in an atom.
What is the current model of the atom?
A nucleus surrounded by a cloud of electron density.
How are electrons arranged in atoms?
In successive principal energy levels/shells.
1st shell is closest to nucleus.
Each shell is split into smaller sublevels (s, p, d, f).
Each subshell split into smaller atomic orbitals.
Each atomic orbital holds a maximum of 2 electrons.
Orbitals have direction represented by cartesian axes: x, y and z.
How many electrons are in principal quantum number 1?
Give the subshells and atomic orbitals.
Electrons: 2
Subshells: 1s
Atomic orbitals: 1s
Principle quantum number - describes the energy of an electron and the most probable distance of the electron from the nucleus.
How many electrons are there in principle quantum number 2?
Give the subshells and atomic orbitals.
Electrons: 8
Subshells: 2s, 2p
Atomic orbitals: 2s, 2px, 2py, 2pz (subscript)
How many electrons are there in principle quantum number 4?
Give subshells and atomic orbitals.
Electrons: 32
Subshells: 4s, 4p, 4d, 4f
Atomic orbitals: 4s, 4px, 4py, 4pz, 4dxy, 4dxz, 4dyz, 4dx^2-y^2, 4dz^2, seven f orbitals
How many electrons are there in principle quantum number 3?
Give subshells and atomic orbitals.
Electrons: 18
Subshells: 3s, 3p, 3d
Atomic orbitals: 3s, 3px, 3py, 3pz, 3dxy, 3dxz, 3dyz, 3dx^2-y^2, 3dz^2
Describe s orbitals. Give details about:
- shape
- how many orbitals there are
- principal quantum number(s) found at
- the number of electrons each orbital holds
Spherical - symmetrical about all three axes.
One s orbital.
Found at all principal quantum numbers.
Hold a maximum of two electrons.
Describe p orbitals. Give details about:
- shape
- how many orbitals there are
- principal quantum number(s) found at
- the number of electrons each orbital holds
Identical in shape (dumbbell) and point in different directions.
Three p orbitals
Found at principle quantum number 2 and above.
Each orbital holds a maximum of 2 electrons.
Describe d orbitals. Give details about:
- shape
- how many orbitals there are
- principal quantum number(s) found at
- the number of electrons each orbital holds
Complicated shape (double dumbbell).
Five d orbitals.
Found at principle quantum number 3 and above.
Each orbital holds a maximum of 2 electrons.
Describe f orbitals. Give details about:
- shape
- how many orbitals there are
- principal quantum number(s) found at
- the number of electrons each orbital holds
Very complicated shape.
Seven f orbitals.
Found at principle quantum number 4 and above.
Each orbital holds a maximum of 2 electrons.
What is meant by orbitals being degenerate?
They have equal energies.
List 3 electron configuration rules.
- Pauli exclusion principle
- The Aufbau principle
- Hund’s rule of maximum multiplicity
What does the Pauli exclusion principle state?
Each orbital contains a maximum of 2 electrons and for 2 electrons to occupy one orbital, the spins must be paired/opposite.
(Clockwise rotation around the axis of the electron represented by up arrow and anticlockwise represented by down arrow).
What does Hund’s rule of maximum multiplicity state?
Electrons occupy a set of degenerate energy orbitals by keeping their spins parallel.
An atom in the ground state adopts a configuration with the greatest number of unpaired electrons.
(Ground state = the lowest possible energy an atom can have)
What does the Aufbau principle state?
Electrons occupy the lowest energy vacant orbital.
How many blocks is the periodic table comprised of?
Four - s, p, d, f.
How is each block named?
For the orbital in which the ‘last’ electron resides.
