Periodic Trends
CSEC CHEMISTRY
NOTES ON PERIODIC TRENDS
From Chemistry for CSEC by Tania Chung-Harris and Mike Taylor Chemistry for CAPE by Susan Maraj and Arnold Samai
Periodic Trends in Group II
Elements in Group II
The elements in Group II are called alkaline earth metals.
Be, Mg, Ca, Sr, Ba, Ra
Beryllium, Magnesium, Calcium, Strontium, Barium, Radium
These elements bond by metallic bonds (intramolecular forces) to form giant metallic structures.
The size of the atoms increases down the group
Physical properties of Group II metals
Ionization
The process of removing an electron from an isolated atom (or an ion) to form a cation.
First ionization: M(g) M+(g) + 1e-
Second ionization: M+ (g) M2+(g) + 1e-
Ease of ionization
All the Group II elements have two electrons in their outer shell. They can lose these electrons to form positive ions. e.g. Ca Ca2+ + 2e-
In the neutral atoms the electrons are held to the nucleus by the electrostatic attraction of the protons in the nucleus. The further the electrons are away from the nucleus, the more weakly they are held. First and second ionization energies are the energies required to remove the first and second electron respectively.
The larger the Group II atom, the smaller the ionization energies. The larger the atom, the easier it is to ionize it.
Reactivity
The reactivity of Group II elements depends on their ease of ionization. Reactivity of Group II INCREASE down the group.
Reactivity with oxygen
Magnesium metal + oxygen gas magnesium oxide
Mg (s) + O2 (g) MgO (s) unbalanced
2Mg (s) + O2 (g) 2MgO (s) balanced
Calcium metal + oxygen gas calcium oxide
Ca (s) + O2 (g) CaO (s) unbalanced
2Ca (s) + O2 (g) 2CaO (s) balanced
Barium metal + oxygen gas barium oxide
Ba (s) + O2 (g) BaO (s) unbalanced
2Ba
NOTES ON PERIODIC TRENDS
From Chemistry for CSEC by Tania Chung-Harris and Mike Taylor Chemistry for CAPE by Susan Maraj and Arnold Samai
Periodic Trends in Group II
Elements in Group II
The elements in Group II are called alkaline earth metals.
Be, Mg, Ca, Sr, Ba, Ra
Beryllium, Magnesium, Calcium, Strontium, Barium, Radium
These elements bond by metallic bonds (intramolecular forces) to form giant metallic structures.
The size of the atoms increases down the group
Physical properties of Group II metals
Ionization
The process of removing an electron from an isolated atom (or an ion) to form a cation.
First ionization: M(g) M+(g) + 1e-
Second ionization: M+ (g) M2+(g) + 1e-
Ease of ionization
All the Group II elements have two electrons in their outer shell. They can lose these electrons to form positive ions. e.g. Ca Ca2+ + 2e-
In the neutral atoms the electrons are held to the nucleus by the electrostatic attraction of the protons in the nucleus. The further the electrons are away from the nucleus, the more weakly they are held. First and second ionization energies are the energies required to remove the first and second electron respectively.
The larger the Group II atom, the smaller the ionization energies. The larger the atom, the easier it is to ionize it.
Reactivity
The reactivity of Group II elements depends on their ease of ionization. Reactivity of Group II INCREASE down the group.
Reactivity with oxygen
Magnesium metal + oxygen gas magnesium oxide
Mg (s) + O2 (g) MgO (s) unbalanced
2Mg (s) + O2 (g) 2MgO (s) balanced
Calcium metal + oxygen gas calcium oxide
Ca (s) + O2 (g) CaO (s) unbalanced
2Ca (s) + O2 (g) 2CaO (s) balanced
Barium metal + oxygen gas barium oxide
Ba (s) + O2 (g) BaO (s) unbalanced
2Ba