Trends of the Elements on the Periodic Table

Atoms want to gain stability ECN trends Periods Groups

What allows atoms to be able to achieve s2p6 Remember: it takes energy to remove an e- from an atom

Atomic radii Size of atoms Measured as distance between nuclei of 2 of the same atoms sitting next to each other

Differs across a Period and down a Group Follows a trend Period

Radii of Ions Metallic Ions On the left and center of the P.T. Ions formed by a loss of e- Ions are smaller than the atoms from which they were formed Nonmetallic ions Located on right side of P.T. Formed by a gain of e- Ions are larger than the atoms they were formed from

Metallic ions have an outer level that resembles Noble Gas at end of preceding period Nonmetallic ions have an outer level that resembles Noble Gas at end of same period HW read pgs. 249-255 pg.255 # 1,2 pg. 257 # 3,4

Ionization Energy amount of energy required to remove an e- from an atom First ionization energy Energy required to remove the most loosely held e- from an atom Atoms/ions have multiple ionization energies

The first ionization energy tends to increase as atomic number increases in a period Ionization energy tends to decrease as atomic number increases in a group Metals are characterized by a low 1st ionization energy Nonetals are characterized by a high 1st ionization energy

Factors affecting Ionization Energy Nuclear charge strength of charge relative to an atoms position in a Period Stronger relative charge, greater ionization energy

Shielding effect Dependent on number of energy levels More levels, more shielding Greater the shielding Lower the ionization energy of the atom

Radius Distance from nucleus to valence electron(s) Short distance(small atom) Large distance(large atom)

Sublevels s,p,d,f Act as shields within energy levels Full or half-filled sublevels More stable Require additional energy to remove e- Ex. Noble gases, Cu & Zn(d sublevel)

Electron Affinity Ability of atom to accept e- Greater nuclear charge Greater affinity Small atoms (non-metals): high Large atoms (metals): low

Group 1 Group 2 Alkali metals Largest atoms in group Lowest affinity Alkaline earth metals 2nd largest group atoms More affinity than Group 1 Still very low

Group 16 Group 17 Very small atoms in Group High affinity Halogens Smallest atoms of any Group Greatest affinity

Group 18 Noble gases Little or no affinity Already have s2p6 ECN Are highly stable Do not need e-

Electronegativity A measure of the attraction for an e- of another atom during the bonding process The greater the electronegativity of an atom,the greater the attraction for another atoms e- Atoms with high Ionization energy have high Electronegativity

Metals Large atoms Low ionization energy and low electronegativity Let e- go in bonding Non-metals Small atoms High ionization energy and high electronegativity Hold on to e- and pull hard on other atoms e- F is the highest, O is second Noble gases have no electronegativity