Atomic Structure Flashcards
Define binding energy.
The energy involved in the formation of a nucleus from free protons and neutrons.
Define principal quantum number.
The number of subshells in each shell.
Define ground state.
When the electrons are in orbitals of lowest available energy level.
Define excited state.
When at least 1 electron absorbs energy and is promoted to a higher energy level.
State the Aufbau Principle.
Electrons always go into an empty orbital with the lowest energy available.
State Hund’s Rule.
Where a number of orbitals of equal energy are available, electrons occupy them singly first before any pairing occurs.
State the Pauli Exclusion Principle.
Each orbital can only hold 2 electrons of opposite spin.
Define atomic number.
Number of protons contained in nucleus is same as number of electrons surrounding the nucleus. No 2 elements can have the same atomic number.
Define mass number.
Total number of protons and neutrons in nucleus.
Define nucleons.
A constituent (neutron or proton) of an atomic nucleus.
Define isotopes.
Atoms with the same number of protons but different number of neutrons. Elements with same chemical properties, but different physical properties, such as melting point, density, radioactivity…
Define orbital.
The region of space where there is a high probability of locating electrons.
Define shell.
A group of orbitals with the same principal quantum number n.
Define subshell.
A group of orbitals in the same shell and of the same energy level.
Define period.
Each horizontal row of elements in the periodic table.
Define group.
Each vertical column of elements in the periodic table.
Define ionisation energy.
The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms.
Define electronvolt.
A unit of energy acquired by an electron when it has accelerated through a potential difference of 1 volt.
Define excitation energy.
The energy required to raise an atom from its ground state to an excited state.
State Heisenberg’s Uncertainty Principle.
A principle that states that it is physically impossible to measure simultaneously the exact position and exact momentum of a particle.
What is wave-particle duality ?
A theory that proposes that every elementary particle has wave and particle properties.
Define relative atomic mass.
Weighted mean mass of masses of all isotopes of an element relative to the mass of 1/12 of carbon-12 atom.
Define convergence limit.
The point where the energy levels get closer together.
What is the screening effect?
It arises from the mutual repulsion between inner shell electrons and outer shell electrons.
Define energy levels.
Electrons in atoms can only have certain energy values.
What is an emission spectrum?
Coloured lines on a black background.
What is an absorption spectrum?
Black lines on a coloured background.
What is the Lyman series?
Electrons falling to lowest energy level (n=1). It is in the UV region.
What is the Bahmer series?
Electrons falling to the second lowest energy level (n=2). It is in the visible region.
What is the Paschen series?
Electrons falling to the third lowest energy level (n=3). It is in the infrared region.
