3. Periodicity Flashcards
Define ‘degenerate’.
Orbitals in the same subshell with the same energy.
Why does the 4s subshell fill and empty first?
- Fills first as it is closer to the nucleus when empty.
- Empties first, as when full, it expands and is further from the nucleus.
What is the trend in successive relative ionisation energy of an element? Why?
- There is a general increase.
- Removing an electron from an increasingly positive ion requires more energy.
- The radius decreases because there is less shielding
Define ‘first ionisation energy’.
The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions.
What three factors does ionisation energy depend on?
- Atomic radius
- Nuclear charge
- Shielding
Why does first ionisation energy decrease as you go down a group?
- More shells.
- Greater shielding.
- Increasing atomic radius.
- Increasing nuclear charge.
Why is there a general increase in first ionisation energy as you go across a period?
- Same number of shells.
- Similar shielding.
- Decreasing atomic radius.
- Increasing nuclear charge.
Why is there a large decrease in first ionisation energy as you go from one period to the next?
- Additional shell.
- Further from nucleus.
- Force of attraction decreases.
Define ‘electronegativity’.
The ability of a bonded atom to attract the pair of electrons in a covalent bond.
What two factors does electronegativity depend on?
- Nuclear charge.
- Distance between nucleus and electron pair.
Why do group 8 have no electronegativity values?
They do not form covalent bonds.
Why does electronegativity increase as you go across the period?
There is greater nuclear charge.
Why does electronegativity decrease as you go down a group?
The atomic radius increases, meaning the nucleus is further away from the electrons and the force of attraction is weaker.
What is the trend in reactivity of group 1? Why?
- As you go down group 1, reactivity increases, as it is easier to lose an electron:
- Increasing electron shells and shielding
- Atomic radius increases.
- Valence electron further from nucleus.
- Attraction between valence electron and nucleus decreases
Define ‘electron affinity’.
The energy released when an additional electron is attached to a neutral atom or molecule.
Which is the only group to have an electron affinity trend? What is this trend?
- Group 1
- As you go down the group, the electron affinity decreases due to increased shielding.
Why does electron affinity increase as you go across a period?
Increasing nuclear charge.
What type of oxide do metals form?
Soluble alkaline oxide
What type of oxide do non-metals form?
Soluble, acidic oxides
Define ‘amphoteric’.
An element or compound that can act both as an acid and a base.
Which oxide is amphoteric?
Aluminium oxide
Is pure water alkaline, acidic or neutral at 298K
Neutral
What is the normal pH of rainwater? Why?
- pH 5.6
- Carbon dioxide dissolves in the water to form carbonic acid.
What naturally produces sulfur dioxides and nitrogen oxides?
Volcanoes and decomposing vegetation.
