honors chem chapter 10

Honors Chem Chapter 10

Periodic Properties

• The position of an elem in the periodic table and its properties are determined by the electron configuration of the atom.

10.1 Radii of Atoms

• Moving from top to bottom in the table, ea period represents a higher principal quantum number–\ as princ quant # incr, size of e- cloud incr– Size of atoms in ea group incr as you go down the

table• Atomic radius – the radius of an atom w/out

regard to surrounding atoms

10.1 Radii of Atoms

• Going across in a period, all atoms have the same n – The (+) chg on the nucleus incr by 1 p+ for every

elem in the period.–\Outer e- cloud is pulled in a little tighter– Atoms generally decr slightly in size from left to

right across a period.

10.1 Radii of Atoms

• Atomic radii increases top to bottom and right to left in the periodic table

10.2 Radii of Ions

• When atoms unite to form molecs or comps, their structures become more stable– When ionic comps are formed, e- are given up by

the metal (+ ion) and gained by the nonmetal (-) ion• Ex) Na has a 3s1 outer config• When it reacts w/ Cl, Cl takes this e- & becomes Cl-

• Na bcomes Na+ (10 e-’s, 11 p+’s)• Na+ ion is smaller than Na atom

10.2 Radii of Ions

• 2 reasons Na+ is smaller than Na– 1. + charged nucleus is attracting fewer e-’s• \ stronger nuclear attraction

– 2. Na+ has only 2 energy levels, while Na has 3• Na+ 1s22s22p6 - same as noble gas – Ne• Noble gas config is stable bec of full outer level

• Noble gas config is stable bec of full outer level

10.2 Radii of Ions

• Cl- is larger than Cl atom– Gains e-, 17 p+’s attracting 18 e-’s• \ weaker nuclear attraction

– Stable bec of noble gas config like Ar

10.2 Radii of Ions

• NaCl is a collection of = #’s of Na+ and Cl- ions– When melted or dissolved, ions are free to move

& conduct a current– Solid NaCl crystal can not conduct electricity bec

ions can’t move – tightly bound• Mobility of electric charge completes a circuit.

10.2 Radii of Ions

• Chemists use ionic radii to discuss size of ions– Na+ is smaller than Na; Mg2+ even smaller than Mg

• Loses 2 e-’s & unbalanced (+) charge is much larger than (-) charge on e- cloud– Cloud shrinks

• S-2 & Cl- are larger than their atoms– Gain e-’s to form ions

• (-) chg is larger than (+) chg – cloud grows

• Si & P don’t easily lose e-’s– Usually for comps by sharing outer e-’s

10.2 Radii of Ions

• Density is a periodic property– Densities vary in a regular way when plotted

against the atomic # of the elems• Metals have high densities• Nonmetals have low densities.

Trends which apply to any row of the periodic table

• Metallic ions – formed by loss of e-’s– Smaller than atoms from which they are formed

• Nonmetallic ions – formed by gaining e-’s– Larger than their atoms

• Metallic ions have stable outer level like the preceding noble gas.

• Nonmetallic ions have stable outer level like the noble gas in the same period.

10.3 Predicting Oxidation Numbers

• Outer level & highest energy e-’s are the ones involved in the rxn of atoms– Most atoms want to become stable (like noble

gases)• Group 1 atoms have 1 e- in outer shell– If it loses 1 e-, it will have a noble gas config• \ oxidation # is +1

– H may also gain 1 e- to have a config like He• \ H can also have a -1 oxidation #


• Group 2 atoms have 2 e-’s in outer level–\ lose 2 e-’s to gain stability • Oxidation # is +2

• Transition elems – highest energy e-’s not in outer level– E-’s are lost from outer (highest) energy level 1st

regardless of order in e- config• May lose some lower level e-’s as well as outer level e-’s


• Sc ends in 4s23d1 – may lose 2 e-’s & have a +2 oxid. #

• *** d e-’s may be lost one at a time–\ may also lose 1 d e- & have a +3 charge too

• Transition elems tend to have >1 oxid #– Vary from +1 to +8

• We may predict Sc to have +2 & +3 oxid #’s– Actually it only has a +3 oxid #


• Ti ends in 4s23d2 – may show +2, +3, +4 (it does)– V has a max oxid # of +5– Cr has a max oxid # of +6– Mn has a max oxid # of +7


• Fe ends in 4s23d6 – has only +2 &+3 oxid #’s– +2 – gives up s e-’s– +3 – gives up s e-’s & only 1 d e- which makes a ½-

full sublevel• Will not give up any more bec it will become less stable


• Group 13 lose 3 e-’s & have +3 oxid #– Tl also has a +1 oxid #• Ends in 6s24f145d106p1

• Large diff in energy betw 6p &6s• \ may lose only 1 e- - the 6p


• Group 14 may have oxid #’s of +2 or +4• Elems in groups 15-17 have outer shells that are >

half full– \ tendency to gain e-’s to achieve an octet

• Group 15 gains 3 e-’s, \ oxid # of -3• Group 16 gains 2 e-’s, \ oxid # of -2• Group 17 gains 1 e-, \ oxid # of -1

• It’s poss for them to lose & have (+) oxid #’s– Tendency to lose e-’s incr as you move down a column.


• For “A” group elems – column # gives maximum (+) oxid # for elems in that column– Column # minus 8 gives lowest poss oxid #

• For “B” group elems, the maximum oxid # is the same as the column label

10.4 First Ionization Energy

• The attraction of an atom for e-’s determines the type of bond formed on a comp.

• Ionization Energy – energy required to remove an e- from an atom

• First Ionization Energy – energy required to remove the most loosely held e- in an atom– (KJ/mole)


• Ionization energies are periodic properties– Tend to incr as Z incr in a period (left to right)– Tend to decr as you move down a group

• Metals have low ioniz energies• Nonmetals have high ioniz energies


• As you go dn a column, outer level e-’s are farther from the nucleus–\ held less tightly– Also, there’s a decr in nuclear attraction betw

outer e-’s & nucleus bec of other e-’s betw them• Shielding Effect

– E-’s are held less tightly – less energy to remove them• \ lower ionization energy


• As you move across the table in a period, atoms get smaller bec of increased nuclear attraction– E-’s held tighter, \ higher ionization energy


• There are deviations from the expected as we move across the table– Small decr betw Be (1s22s2) & B (1s22s22p1)• Be – a 2s e- must be removed from a fairly stable atom• B – a lone 2p e- must be removed

– Ion is more stable, \ takes less energy

– Small decr betw N(1s22s22p3) & O (1s22s22p4)• N is more stable w/ ½-filled sublevel

Factors Affecting Ionization Energy

1. Nuclear Charge (nuclear attraction)2. Shielding Effect3. Radius 4. Sublevel

10.5 Multiple Ionization Energies

• It’s poss to meas 2nd, 3rd, … ionization energies of an atom

• Ionization energy incr w/ removal of ea successive e-– Ex) 2nd ioniz energy of Al ~ 3x the first• 1st ioniz removes a p e-• 2nd ioniz removes an s e- from a full sublevel• 3rd ioniz energy is ~ 1 ½ X the 2nd

– 2nd & 3rd e-’s are in the same s sublevel

10.5 Multiple Ionization Energies

• **Successive ioniz energies incr bec the nuclear chg remains the same as the # of e-’s decr–\ remaining e-’s are held even tighter– 4th ioniz energy of Al is ~ 4 X the 3rd

• After 3rd e- is removed, 4th e- is in lower energy level– Closer to nucleus, \ held MUCH tighter

10.6 Electron Affinities

• Attraction of an atom for an e- (usually an extra e-)

• Factors which affect e- affinity are the same as those affecting ioniz. Energy

• Generally – as e- affinity incr, ioniz energy incr– Metals have a low e- affinity– Nonmetals have a high e- affinity

10.6 Electron Affinities

• Electron affinities show periodic trends– Not as regular as ioniz energies

• As you go across a period, e- affinities incr– Greater nuclear attraction for e- bec of incr

nuclear charge– There are exceptions in this trend bec of full & ½-

full sublevels

• All these properties are involved when atoms react w/ ea other to form compounds.– Props of compounds depend on the structures of

their atoms.

honors chem chapter 10

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