Periodic Patterns Flashcards
What is covalent radius
Half the distance between nuclei of atoms that are covalently bonded together
As you go down a group, covalent radius…
Increases
Why does covalent radius increase as you go down a group
- number of electron shells increases
- increased shielding
- electrons further away from nucleus
- atom size increases
As you go across a period, covalent radius…
Decreases
Why does covalent radius decrease as you go across a period
- electrons are gradually filling up energy levels
- more protons
- increased nuclear charge
- electrons pulled in closer and tighter
- atom size decreases
What unit is atomic size measured in
Picometers (pm)
1 x 10^-12 m
What is Van der Waals radius
Half the distance between atoms nuclei that aren’t bonded together
What is the first ionisation energy
The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms
What is the general equation for the first ionisation energy
M (g) ——> M+ (g) + e-
What is the second ionisation energy
The energy required to remove a second mole of electrons
What is the general equation for the second ionisation energy
M+ (g) ——> M 2+(g) + e-
What is the third ionisation energy
The energy required to remove a third mole of electrons
What is the general equation for the third ionisation energy
M 2+(g) ——> M 3+(g) + e-
As you go down a group, ionisation energy…
Decreases
Why does ionisation energy decrease as you go down a group
- number of electron shells increases
- atomic size increases
- outer electrons are further away from nucleus
- increased shielding
- less energy required to remove e-
As you go across a period, ionisation energy…
Increases
Why does ionisation energy increase as you go across a period
- gradually filling up e- shells
- more protons
- nuclear charge increases
- outer e- held tighter and closer to nucleus
- atomic size decreases
- more energy required to remove e-
What is electronegativity
The measure of an atoms attraction for bonding electrons
What does it mean if an atom is said to be highly electronegative
It has a strong attraction for bonding electrons
As you go down a group, electronegativity…
Decreases
Why does electronegativity decrease as you go down a group
- number of e- shells increases
- shielding increases
- outer e- further away from nucleus
- less attraction for bonding e-
As you go across a period, electronegativity…
Increases
Why does electronegativity increase as you go across a period
- more protons
- nuclear charge increases
- covalent radius decreases
- +ve nucleus attracts bonding electrons more strongly
Why does group 8 (noble gases) not have electronegativity values
They have no bonding electrons
