This document summarizes key concepts about the periodic table including: - How the elements were discovered and their electron configurations - How cations and anions are formed by gaining or losing electrons to achieve a noble gas configuration - Trends in atomic radius, ionization energy, and electronegativity across periods and down groups - How the reactivity of elements in groups 1A, 2A, 3A and 7A changes based on their tendency to gain, lose, or share electrons.

1. The Periodic Table
Chapter 8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 8.1
When the Elements Were Discovered

3. 8.2
ns1
ns2
ns2
np1
ns2
np2
ns2
np3
ns2
np4
ns2
np5
ns2
np6
d1
d5
d10
4f
5f
Ground State Electron Configurations of the Elements

4. 8.2
Classification of the Elements

5. Electron Configurations of Cations and Anions
Na [Ne]3s1
Na+
[Ne]
Ca [Ar]4s2
Ca2+
[Ar]
Al [Ne]3s2
3p1
Al3+
[Ne]
Atoms ___________ electrons
so that cation has a noble-gas
outer electron configuration.
H 1s1
H-
1s2
or [He]
F 1s2
2s2
2p5
F-
1s2
2s2
2p6
or [Ne]
O 1s2
2s2
2p4
O2-
1s2
2s2
2p6
or [Ne]
N 1s2
2s2
2p3
N3-
1s2
2s2
2p6
or [Ne]
Atoms ____________
electrons so that anion
has a noble-gas outer
electron configuration.
Of Representative Elements
8.2

6. +1
+2
+3
-1
-2
-3
Cations and Anions Of Representative Elements
8.2

7. Na+
: [Ne] Al3+
: [Ne] F-
: 1s2
2s2
2p6
or [Ne]
O2-
: 1s2
2s2
2p6
or [Ne] N3-
: 1s2
2s2
2p6
or [Ne]
Na+
, Al3+
, F-
, O2-
, and N3-
are all ________________ with Ne
What neutral atom is isoelectronic with H-
?
__________________________________
8.2

8. Electron Configurations of Cations of Transition Metals
8.2
When a ___________________ is formed from an atom of a
_______________________, electrons are always removed
first from the ns orbital and then from the (n – 1)d orbitals.
Fe: [Ar]4s2
3d6
Fe2+
: [Ar]4s0
3d6
or [Ar]3d6
Fe3+
: [Ar]4s0
3d5
or [Ar]3d5
Mn: [Ar]4s2
3d5
Mn2+
: [Ar]4s0
3d5
or [Ar]3d5

9. ______________________________ (Zeff)
is the “positive charge” felt by an electron.
Na
Mg
Al
Si
11
12
13
14
10
10
10
10
1
2
3
4
186
160
143
132
ZeffCoreZ Radius
Zeff = Z - σ 0 < σ < Z (σ = ____________________)
Zeff ≈ Z – number of inner or core electrons
Within a Period
as Zeff increases,
________________
decreases
8.3

10. 8.3

11. Atomic Radii
8.3

12. 8.3

13. Cation is always ________________
than atom from which it is formed.
Anion is always _________________
than atom from which it is formed.
8.3

14. 8.3

15. ______________ is the minimum energy (kJ/mol) required to
remove an electron from a gaseous atom in its ground state.
I1 + X (g) X+
(g) + e-
I2 + X (g) X2+
(g) + e-
I3 + X (g) X3+
(g) + e-
I1 first ionization energy
I2 second ionization energy
I3 third ionization energy
8.4
I1 < I2 < I3

16. Filled n=1 shell
Filled n=2 shell
Filled n=3 shell
Filled n=4 shell
Filled n=5 shell
8.4

17. General Trend in First Ionization Energies
8.4
Increasing First Ionization Energy
IncreasingFirstIonizationEnergy

18. ____________________________ is the negative of the
energy change that occurs when an electron is accepted
by an atom in the gaseous state to form an anion.
X (g) + e-
X-
(g)
8.5
F (g) + e-
X-
(g)
O (g) + e-
O-
(g)
∆H = -328 kJ/mol EA = +328 kJ/mol
∆H = -141 kJ/mol EA = +141 kJ/mol

19. 8.5

20. 8.6
Reason: _____________________________________________

21. Group 1A Elements (ns1
, n ≥ 2)
M M+1
+ 1e-
2M(s) + 2H2O(l) 2MOH(aq) + H2(g)
4M(s) + O2(g) 2M2O(s)
Increasingreactivity
8.6

22. Group 2A Elements (ns2
, n ≥ 2)
M M+2
+ 2e-
Be(s) + 2H2O(l) No Reaction
Increasingreactivity
8.6
Mg(s) + 2H2O(g) Mg(OH)2(aq) + H2(g)
M(s) + 2H2O(l) M(OH)2(aq) + H2(g) M = Ca, Sr, or Ba

23. Group 3A Elements (ns2
np1
, n ≥ 2)
8.6
4Al(s) + 3O2(g) 2Al2O3(s)
2Al(s) + 6H+
(aq) 2Al3+
(aq) + 3H2(g)

24. Group 7A Elements (ns1
np5
, n ≥ 2)
X + 1e-
X-1
X2(g) + H2(g) 2HX(g)
Increasingreactivity
8.6