1a. Periodicity Flashcards
What is covalent radius?
Half the distance between bonding nuclei
Why is there no covalent radii for the Noble Gases?
They do not form covalent bonds.
What is the trend for covalent radius across a period?
Decreases due to greater pull of extra protons on shells
What is the trend for covalent radius down a group?
Increases due to greater number of electron shells (levels)
Why is there no covalent radius for the Noble Gases?
There are no bonding nuclei to measure between.
What is 1st Ionisation energy?
The energy required to remove 1 mole of electrons from 1 mole of atoms in the gaseous state
What is the trend for ionisation energy across a period?
Increases due to greater pull of extra protons on outer electrons
What is the trend for ionisation energy going down a group?
Decreases due to greater shielding effect of extra shells and greater distance of outer electrons from nucleus
Why is 2nd ionisation energy always greater than the 1st?
It takes more energy to remove an electron from a positively charged ion
Why is the 2nd ionisation energy of group 1 metals so much higher than the 1st?
or
Why is the 3rd ionisation energy of group 2 metals so much higher than the 2nd?
or
Why is the 4rd ionisation energy of group 3 metals so much higher than the 3rd?
- electron is being removed from a stable (full) shell or electron arrangement
- this shell has less shielding effect from the nucleus
- this shell lies closer to the nucleus
What is electronegativity?
The attraction an atom’s nucleus has for bonding electrons
What is the trend fo electronegativity down a group
Decreases due to
- greater shielding effect of extra shells
- greater distance of bonding electrons from nucleus
What is the trend for electronegativity across a period
Increases due to
- greater pull of extra protons on shared pair of electrons
- bonding electrons lying closer to nucleus
Why is there no electronegativity value for the noble gases?
They do not form (covalent) bonds due to having a complete outer shell
