S3.1 The periodic table HL Flashcards
What evidence do discontinuities in first ionisation energy provide?
Discontinuities in first ionisation energy provide evidence for the existence of energy sublevels within atoms, as shown by anomalies in ionisation energy trends across the periodic table.
What causes the anomalies in ionisation energy trends?
Anomalies in ionisation energy trends, or discontinuities, are caused by the occupation of electrons in different energy sublevels, affecting their attraction to the nucleus.
The transition from an s to a p sublevel results in a weaker attraction between the nucleus and the outer valence electrons, leading to a lower than expected ionisation energy.
What does the pattern of discontinuities across the periodic table indicate?
The pattern of discontinuities across the periodic table supports the existence of sublevels within the main energy levels of atoms, correlating with changes in electron configuration.
What properties do transition elements exhibit?
Variable oxidation states, high melting points, magnetic properties (paramagnetic and ferromagnetic), catalytic properties, formation of colored compounds, formation of complex ions with ligands.
Why do transition elements have variable oxidation states?
Due to the involvement of both s and d orbitals in bonding, which are close in energy, allowing electrons to be lost from either, leading to different oxidation states.
How are the electron configurations of ions of the first-row transition elements determined?
By removing electrons first from the s orbital followed by the d orbitals. For example, Fe ([Ar] 4s2 3d6) forms Fe2+ ([Ar] 3d6) and Fe3+ ([Ar] 3d5) by removing electrons from the 4s orbital first, then the 3d orbital.
Why do transition elements exhibit variable oxidation states?
Transition elements have variable oxidation states due to their unique electron configurations, with valence electrons in both s and d sublevels. Electrons are typically lost from the s-sublevel first, followed by the d-sublevel, allowing these elements to form ions with multiple oxidation states.
How are the electron configurations of ions for the first-row transition elements determined?
For first-row transition elements, ions’ electron configurations result from losing electrons from the 4s sublevel before the 3d sublevel. For example, Fe3+ is formed by losing two electrons from 4s and one from 3d, leading to a configuration of 1s²2s²2p⁶3s²3p⁶3d⁵.
How is a colour wheel used to deduce wavelengths and frequencies of light absorbed by a solution?
The colour wheel predicts absorbed wavelengths and colours based on a solution’s appearance. If a solution absorbs certain wavelengths, it reflects or transmits complementary colours, opposite on the colour wheel, allowing inference of absorbed wavelengths from the solution’s observed colour.
Why do transition metal complexes appear coloured?
Transition metal complexes are coloured due to d-sublevel splitting in their electron configuration. Ligands coordinating with metal ions split the d-orbital energy levels. Electrons can absorb visible light to transition between these levels, with the complex absorbing specific wavelengths. The observed colour is the complementary colour of the absorbed light, influenced by the metal ion’s nature, its oxidation state, ligand types, and the complex’s geometry.
