1. Chapter 6 The Periodic Table 6.3 Periodic Trends
6.1 Organizing the Elements
6.2 Classifying the Elements
6.3 Periodic Trends
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2. Trends in Ionization Energy
Atomic Radius – one-half the distance between the nuclei of two atoms of the same element when the atoms are joined.
Ionization Energy – energy required to remove one electron from an atom.
Electronegativity – ability of an atom of an element to attract electrons when the atom is in a compound.
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3. Trends in Atomic Size
Atomic Radius: one-half the distance between the nuclei of two atoms of the same element when the atoms are joined.
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4. Trends in atomic size. Trends in Atomic Size
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5. Trends in Atomic Size
In general, atomic size increases from top to bottom within a group, and decreases from left to right across a period.
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6. Which atom in each pair has the larger atomic radius? Li or K Ca or Ni
CHEMISTRY & YOU
Which atom in each pair has the larger atomic radius?
Li or K
Ca or Ni
Ga or B
O or C
Cl or Br
f) Be or Ba
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7. Ions An atom or group of atoms that has a positive or negative charge.
Atoms become ions when electrons are lost or gained.
Atoms can become cations or anions
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8. Cation – ion with a positive charge
Ions
Cation – ion with a positive charge
Metals form cations.
Smaller than the atoms they form from
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9. Anion – ion with a negative charge
Ions
Anion – ion with a negative charge
Nonmetals form anions.
Larger than the atom they form from
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10. Group Trends in Ionic Size
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11. The figure below summarizes the group and period trends in ionic size.
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12. Trends in Ionization Energy
Ionization Energy – energy required to remove one electron from an atom.
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13. Ionization Energies of Some Common Elements
Interpret Data
Ionization Energies of Some Common Elements
Symbol
First
Second
Third H
1312
He (noble gas)
2372
5247 Li
520
7297
11,810 Be
899
1757
14,840 C
1086
2352
4619 O
1314
3391
5301 F
1681
3375
6045
Ne (noble gas)
2080
3963
6276 Na
496
4565
6912 Mg
738
1450
7732 S
999
2260
3380
Ar (noble gas
1520
2665
3947 K
419
3096
4600 Ca
590
1146
4941
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14. Electronegativity Values for Selected Elements
Interpret Data
Electronegativity – ability of an atom of an element to attract electrons when the atom is in a compound.
Electronegativity Values for Selected Elements H
2.1 Li
1.0 Be
1.5 B
2.0 C
2.5 N
3.0 O
3.5 F
4.0 Na
0.9 Mg
1.2 Al Si
1.8 P S Cl K
0.8 Ca Ga
1.6 Ge As Se
2.4 Br
2.8 Rb Sr In
1.7 Sn Sb
1.9 Te I Cs
0.7 Ba Tl Pb Bi
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15. Trends in Electronegativity
In general, electronegativity values decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a period.
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16. Trends in Electronegativity
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17. CHEMISTRY & YOU
Arrange the following groups of elements in order of increasing ionization energy.
Be, Mg, Sr → Sr, Mg, Be
Bi, Cs, Ba → Cs, Ba, Bi
Na, Al, S → Na, Al, S
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18. 1. Which has the smallest ionization energy;
Trends in Atomic Size
Practice Problems
1. Which has the smallest ionization energy;
Sodium, Calcium, Potassium, Magnesium
2. List in order of increasing ionization energy (smallest to largest)
Beryllium, Cesium, Oxygen,
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19. Which element in each pair has a higher electronegativity value?
CHEMISTRY & YOU
Which element in each pair has a higher electronegativity value?
Cl or F
C or N
Mg or Ne
As or Ca
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20. CHEMISTRY & YOU
When the elements in each pair are chemically combined, which has a greater attraction for electrons?
Ca or O
O or F
H or O
K or S
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21. Which element in each pair has the larger atomic radius? Na or Li
CHEMISTRY & YOU
Which element in each pair has the larger atomic radius?
Na or Li
Sr or Mg
C or Ge
Se or O
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22. Which particle has the larger radius in each atom/ion pair?
CHEMISTRY & YOU
Which particle has the larger radius in each atom/ion pair?
Na, Na+
S, S2-
I, I-
Al, Al3+
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23. Which element in each pair has a greater first ionization energy?
CHEMISTRY & YOU
Which element in each pair has a greater first ionization energy?
Li or B
Mg or Sr
Cs or Al
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