Penodcly
8. PERODIC TABLE. 8.2 TRENDs IN PERIOD 3
lrends across perod 3
MELTING
Pt Na, Mq and Al have qant mttallie
structures with strong metallie bonds
S has aqiant covalent structure
Ps, c are simpie moiec uies with only
Van der Waals íorces
Na Ma Al Si P S Cl Ar
Ar is monatomC and hard to potarise
AL has a hgher melting point than Na and Ma beause it has the
strongest metallie bonds due to hugher charge On ions and more deloalised
electrons so theres a stronger electrustatic forces of attraction
higher than Pand (l as the moiecule is the largest ’
larger
number of electrons ’ strongest Van de Waals
Properties
- Atomnic radius decreases across a perIOd
increased nuclear charge, no add1t1onal shield1nq means electrons are
pulled doser to the nucleus
Ist ionisation enerqy increases aross a peciodr
increased nuclear charge, Similar shieldinq .decreas ed atomIc ocdius
means it's more difficult to remove an electron
Exceptions
mol to 1E trend
kd Between qroup 2 and 3- AL loses a
/ X electron, not a 3s elect ron sa it takes less
l¬
ehergy to (emove
Ist
Between group 5 and 6 S has a par ot
electrons in a 3p orbital whichepel and
No M Al Si PS C Ar So are easier to remove
8. PERODIC TABLE. 8.2 TRENDs IN PERIOD 3
lrends across perod 3
MELTING
Pt Na, Mq and Al have qant mttallie
structures with strong metallie bonds
S has aqiant covalent structure
Ps, c are simpie moiec uies with only
Van der Waals íorces
Na Ma Al Si P S Cl Ar
Ar is monatomC and hard to potarise
AL has a hgher melting point than Na and Ma beause it has the
strongest metallie bonds due to hugher charge On ions and more deloalised
electrons so theres a stronger electrustatic forces of attraction
higher than Pand (l as the moiecule is the largest ’
larger
number of electrons ’ strongest Van de Waals
Properties
- Atomnic radius decreases across a perIOd
increased nuclear charge, no add1t1onal shield1nq means electrons are
pulled doser to the nucleus
Ist ionisation enerqy increases aross a peciodr
increased nuclear charge, Similar shieldinq .decreas ed atomIc ocdius
means it's more difficult to remove an electron
Exceptions
mol to 1E trend
kd Between qroup 2 and 3- AL loses a
/ X electron, not a 3s elect ron sa it takes less
l¬
ehergy to (emove
Ist
Between group 5 and 6 S has a par ot
electrons in a 3p orbital whichepel and
No M Al Si PS C Ar So are easier to remove
