Trends in Periodic Table - Ch7 Flashcards
Atomic radius
Half the distance between the nuclei of two atoms of the same element that are joined together by a single covalent bond.
Trend of atomic radius across period and why?
Decrease:
- More electrons
- More effective nuclear charge
- No charge in screening
Trend of atomic radius down a group and why?
Gets larger:
- More energy levels
- More screening
- Decreasing effective nuclear charge
Ionisation energy
The minimum energy required to completely remove the most loosely bound electron from a neutral gaseous atom in its ground state.
Trend of ionisation energy across period and why?
Increases:
- Atomic radius is decreasing
- Effective nuclear charge is increasing
- No charge in screening
Trend of ionisation energy down a group and why?
Decreases:
- Atomic radius is increasing
- Effective nuclear charge is decreasing
- More screening
Exceptions across periodic table: Li (520), Be (900), B (801). Why Be higher?
SPDF configuration:
- The 2s in Be is full, therefore it is very stable
Second ionisation energy
Energy required to remove an electron from an ion with one positive change in the gaseous state.
Why is 2nd I.E always bigger than 1st?
Taking from a monopositive ion.
Electronegativity:
Relative attraction that an atom in a molecule has for the shared pair of electrons in a covalent bond.
Trend of electronegativity across period and why?
Increases:
- Atomic radius is decreasing
- Effective nuclear charge is increasing
- No charge in screening
Trend of electronegativity down a group and why?
Decreases:
- Atomic radius is increasing
- Effective nuclear charge is decreasing
- More screening
Trends in alkali metals group
Reactivity increases down a group. (Give reasons of other trends)
Trends in halogens group and why?
Reactivity decreases going down a group, because electronegativity increases up the group.
