Flashcards in The atom and redox Deck (21)
What is an isotope?
An isotope is an atom of the same element with the same number of protons and electrons but different number of neutrons.
What is the atomic number of an atom?
The number of protons it has.
What is the mass number of atom?
The total number of protons and electrons in its nucleus.
What is the relative atomic mass of an element?
The weighted mean mass of an atom of an element relative to one twelfth of the mass of a carbon-12 atom.
Relative isotopic mass?
The mass of an atom of an isotope of an element relative to one twelfth of the mass of an atom of carbon-12.
What is the first ionisation energy?
The energy required to form one mole of 1+ ions from 1 mole of gaseous atoms by removing one electron from each atom.
What is an orbital?
A space in an atom that can hold up to two electrons of opposite spins.
What is a sub-shell?
Orbitals with the same principal quantum numbers grouped together in terms of their type and shape.
What is the electron configuration of an atom?
The arrangement of electrons in an atom in terms of their principle quantum number, sub-shell and orbital.
What is the principle quantum number?
The relative overall energy level of each orbital which increases as distance from nucleus increases.
What is the relative molecular mass?
The weighted mean mass of a simple molecule relative to one twelfth of the mass of an atom of carbon-12.
What is the relative formula mass?
The weighted mean mass of a formula unit relative to one twelfth of the mass of an atom of carbon-12.
What is the formula to determine the number of electrons a shell can hold?
2n^2, where n = principal quantum number.
What is so special about the way d shells fill up?
d shells actually have a higher energy level than the s shells of the next principal quantum number. This means that the s shells will fill up before the d shells of the quantum level below do.
What is so special about the electron configuration of chromium and copper.
If you look at the electron configuration, both elements do not have complete 4s orbitals. This is because as the electrons fill up, the 3d shell will reach a state of lower energy compared to the 4s shell. When this happens, an electron from the 4s shell moves to the 3d shell and the energy levels are balanced again. However, after the first ionisation of the two elements, electron configuration shifts back to what is expected as losing an electron brings the 3d shell back to a higher energy level.
What are the 3 factors affecting first ionisation energies?
1. Distance from nucleus.2. Amount of electron shielding.3. Charge of the nucleus.
What are successive ionisation energies?
The energy required to remove exactly one mole of electrons from one mole of gaseous species by removing one electron from each atom.
What is oxidation?
The loss of electrons or an increase in oxidation number.
What is reduction?
A gain in electrons or a reduction in oxidation number.
What is an oxidising agent?
A reagent that oxidises (takes electrons from) another species.