Periodictable - Questions

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So atomic radius (size) determined by:

1. Larger value of n for atom in a group, the larger the atom size. Size _ from top to bottom in group.

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Size across a period

As go across a period (n stays the same), the no. of protons in the nucleus increases. The e’s are very spread out and each electron feels the pull of the increasing +charge of the nucleus uninfluenced by the other electrons and size as go from left to right across a period.

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Group size increases

Period size decreases (with some exceptions)

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3.62; Arrange each of the lists according to increasing atomic size:

Al, S, P, Cl, Si

In, Ga, Al, B, Tl

Sr, Ca, Ba, Mg, Be

P, N, Sb, Bi, As

Na, K, Mg

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Ion size

Same charge, in group, size creases

Size of parent to cation:

Parent cation

Size of parent to anion:

Parent anion

Fe2+ Fe3+

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Which is smaller?

Cl or Cl-

Na or Na+

O2- or S2-

Mg2+ or Al3+

Au+ or Au3+

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Note for isoelctronic series:

Na+, Mg2+, Al3+, N3-, O2-, F-,

N3-> O2-> F-> Na+> Mg2+> Al3+

Most positive ion the smallest, most negative the largest

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Ionization energy

Minimum energy required to remove an electron from a ground-state, gaseous atom

Energy always positive (requires energy)

Measures how tightly the e- is held in atom (think size also)

Energy associated with this reaction:

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Trends in ionization energy

Top to bottom in group: 1st I.E. creases. Why?

Across a period, 1st I.E. creases (irregularly) Why? Note that noble gases have the largest I.E. in a given period; the halogens the next highest; the alkali metals the lowest, etc.

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In a group (column), I1 decreases with increasing Z.

valence e’s with larger n are further from the nucleus, less tightly held