1 Reactivity – When reacting, atoms collide so their outer-most electrons (valence electrons) interact Those electrons that are “seen” by another atom or molecule – Valence electrons are the reacting electrons – Some atoms gain electrons, while others lose them metals are “born losers” – always give up their electrons to become more stable (to end with a complete valence shell – a complete octet) non-metals acquire those electrons lost by the metal – take on electrons to become more stable (to fill up their orbitals and complete the octet)

2 Silver (Ag) – In the 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 1 4d 10 state 1 valence electron to react – Ag wants to lose the electron, emptying its 5s-sublevel – Becomes Ag + » 47 protons but only 46 electrons – The +1 ion is the most stable configuration that Ag can be in

3 Lead (Pb) – Pb has a partially filled and a completely filled sublevel as its valence shell 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 2 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 6s 2 6p 2 – Pb wants to exist in the lowest energy state possible Pb loses 6p 2 electrons to become Pb 2+ ion - lead(II) – 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 6s 2 Pb loses 6s 2 6p 2 electrons to become Pb 4+ ion – lead(IV) –1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 Valence Electrons

4 Tin (Sn) – Tin has very similar properties to lead, except that its most abundant state is Sn 4+ - tin(IV) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 2 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 5s 2 5p 2 Lose 5s 2 5p 2 electrons to become Sn 4+ Lose just 5p 2 electrons to become Sn 2+ Valence Electrons

5 Bismuth (Bi) and Thallium (Tl) – Both bismuth and thallium exhibit similar reactivity Tl: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 1 – 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 6s 2 6p 1 Tl can lose either the 6p 1 or the 6s 2 6p 1 electrons to form a +1 or +3 species respectively Bi: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 3 – 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 6 4d 10 4f 14 5s 2 5p 6 5d 10 6s 2 6p 3 Bi can lose the 6p 3 or the 6s 2 6p 3 electrons to form the +3 or +5 ions respectively

6 Halogens – The halogens have a similar desire for stability and lower energy, but it’s acquired differently Fluorine – 1s 2 2s 2 2p 5 [He] 2s 2 2p 5 Chlorine – 1s 2 2s 2 2p 6 3s 2 3p 5 [Ne] 3s 2 3p 5 Bromine – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 – 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 4p 5 – All halogens have a completely filled s-sublevel and are 1 electron from a full p-sublevel They can gain 1 electron to fill their p-sublevels – “Completing the octet” What do you notice about the valence electrons?

7 Halogens – When the halogens gain an electron, they become -1 anions (F -, Cl -, Br - ) – In completing their octets, halogens become isoelectronic with the next element, the noble gas Two species are isoelectronic if they have the same electronic configurations – F - is isoelectronic with Ne » 1s 2 2s 2 2p 6 – Cl - is isoelectronic with Ar » 1s 2 2s 2 2p 6 3s 2 3p 6 – Br - is isoelectronic with Kr » 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6

8 To be isoelectronic … – O 2- is isoelectronic with Ne 1s 2 2s 2 2p 6 – The same way that non-metals can be isoelectronic with the noble gases, metals can too Na + (losing the 3s 1 electron) is isoelectronic with Ne – 1s 2 2s 2 2p 6 (complete octet is in the 2nd energy level) Sr 2+ is isoelectronic with Kr – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 Fr + is isoelectronic with Rn – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6

9 Metals and Isoelectronic – Some metals have similar (but not exact) electron configurations to other atoms when charged – Zn can lose its 4s 2 electrons, giving it the same valence configuration as Ar 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 Zn has a full d-sublevel, whereas Ar does not – Zn 2+ :1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 – Ar:1s 2 2s 2 2p 6 3s 2 3p 6 Zn is pseudo-isoelectronic with Ar

10 Isoelectronic or Pseudoisoelectronic? – State whether the atoms are isoelectronic or pseudoisoelectronic with the indicated noble gases Na + Ne Ca 2+ Ar Cu + Ar I - Xe Pd 4+ Kr Hf 4+ Xe Isoelectronic Pseudo-isoelectronic Isoelectronic Pseudo-isoelectronic Isoelectronic

11 Electronic Trends in the Periodic Table Alkali Metals (Group 1) – H1s 1 – Li1s 2 2s 1 – Na1s 2 2s 2 2p 6 3s 1 – K1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 – Rb1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 1 – Cs1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 1 – Fr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 1

12 Electronic Trends in the Periodic Table Alkaline Earth Metals (Group 2) – Be1s 2 2s 2 – Mg1s 2 2s 2 2p 6 3s 2 – Ca1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 – Sr1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 – Ba1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 – Ra 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 2

13 Electronic Trends in the Periodic Table Halogens (Group 17) – F1s 2 2s 2 2p 5 – Cl1s 2 2s 2 2p 6 3s 2 3p 5 – Br1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 – I1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 5 – At 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 5

14 Electronic Trends in the Periodic Table Nobel Gases (Group 18) – He1s 2 – Ne1s 2 2s 2 2p 6 – Ar1s 2 2s 2 2p 6 3s 2 3p 6 – Kr1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 – Xe1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 – Rn 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6