Metals Characteristics Variation in Periodic Table

Every metal has different characteristics than a another metal. Metals are located in all blocks of the periodic table. (s,p,d,f blocks) Metals prefer to eliminate electrons and form positive ions always and ionic compounds in most occasions.



In this lesson, we discuss following topics.

  • Physical properties differences of metals according to the block and groups
  • Chemical reactivity with oxygen, Water, acids and more compounds


Metals in periodic table

Metals are located in all blocks in periodic table. ( s block, p block, d block, f block). But their characteristics such as chemical reactivity are very much different from metal to metal.


s block metals

Group Metals
Alkali Metals - IA Group Li, Na, K, Rb, Cs, Fr
Alkali Earth Metals - IIA Group Be, Mg, Ca, Sr, Ba, Ra

p block metals

Group Metals
IIIA Group Al, Ga, In, Tl
IVA Group Ge, Sn, Pb
VA Group Sb, Bi
VIA Group Po


3d metals

Metals
3d Metals Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn


Few examples to explain metal characteristics are different

Sodium, a s block metal reacts with water very vigorously to give sodium hydroxide and hydrogen gas. But lead, a p block element does not reacts with water. Both are metals. But they have different characteristics.

Both lithium and beryllium are s block metals. But only lithium reacts with water.




Common characteristics of metals

  • Metals prefer to eliminate electrons in their last shell. Therefore they form cations. Also oxidation number of a metal in a compound is always a positive value.

Examples to oxidation number of metals

  • NaCl : Oxidation number of Na is +1
  • CaCO3: Oxidation number of Ca is +2
  • CuSO4: Oxidation number of Cu is +2

Variable Oxidation Numbers

d block metals show variable oxidation numbers. As an example, iron can form +2 and +3 oxidation numbers. According to the oxidation number, colours, solubility and more parameters are changed. Few examples are discussed now.


  • Let's consider solids of two oxidation states of iron, +2 and +3. So aqueous compounds may be FeCl2 and FeCl3. FeCl2 is greenish white crystalline solid. But, FeCl3, is brownish-black colour.

  • Sometimes solubility varies with oxidation number of metal. Aqueous CuCl2 is a blue colour solution and has a solubility of 70.6 g/100 cm3 of water at 00C. But CuCl is a white precipitate.

  • When metals have higher oxidation number or state, they hydrolysis and form an acidic solution. As an example, aqueous aluminium chloride solution is acidic.



Metallic characteristics variation going down the group

Alkali metal series (group IA) is chosen to discuss this variation.

  • When going down the group, metallic radius increases. It will decrease the electron's attraction towards nucleus which will ease the removing electron of the last energy level.
  • So potassium has higher metallic characteristics than sodium because potassium is situated below the sodium in the periodic table.

Metallic characteristics along a period (left to right)

Metallic characteristics decreases along the period when going from left to right. When consider sodium, magnesium and aluminium, sodium has the best metallic characteristic while aluminium is the lowest from those three.



Physical properties of metals


Melting and boiling points of metals

First, we see some metals from different blocks to get an idea how melting and boiling points vary. Take sodium, aluminium and vanadium as metals.


You know, melting and boiling points of metals mainly depends on the metallic lattice. The stronger the lattice, melting and boiling points increase.

Aluminium has a strong metallic lattice than sodium. So melting and boiling points of aluminium is higher than sodium. Vanadium has the highest melting and boiling point in 3d electrons because it's metallic lattice is very strong. Vanadium can participate five electrons to the lattice while sodium and aluminium can participate one and three respectively.


Summary about meting and boiling points of s, p, d block metals

s block elements are soft and have lesser melting and boiling points than d block metals.


Group 1, group 2 melting and boiling points in a same period

In a same period, group 2 metals have higher melting and boiling points than group 1 metals.

Example:

Magnesium has a strong metallic lattice and have a higher melting and boiling point than sodium.



Electronegativity

Usually electronegativity of metals are less than non-metals. Electronegativity of sodium and oxygen are 0.9 and 3.5 in pauling scale (fluorine has the maximum value of 4.0). 3d metals have higher electronegativity than s block metals.



Which metals have the most metallic characteristics, s or 3d?

Metallic characteristic depend on easiness of valence electrons removing. If a metal can remove its valence electrons easily, they have good metal characteristics.

  • s block metals remove their electrons very easily than d block metals. Check first ionization enthalpy value, second enthalpy value and more. When ionization enthalpy is low, it means that removing electron is easy to remove rather than an electrons which have higher ionization enthalpy.


Density

Atomic volumes of 3d elements are lower than those of s block metals due to increased nuclear charge. Therefore density of 3d elements are higher than s block elements.



Magnetic Properties

Many compounds of the transition elements (contains 3d) are paramagnetic due to partially filled electron shells. No magnetism is shown by alkali metals and alkali earth metals.


Magnetic metals in the periodic table

  • Iron
  • Cobalt
  • Nickel
  • Manganese


Conductivity

Conductivity is a major metal characteristic because it has a wide range of applications in the world.

  • Silver is the best electric and thermal (heat) conductor metal. Copper, gold are next good conductors for electricity and heat.
  • aluminum, zinc, nickel, iron, and platinum are other good conductors.

How metals conduct electricity and heat and why some metals have higher conductivity?

Due to presence of free electrons which are movable. Number of free electrons are depend on the valence of the metal. Also according to the crystal structure of metal, conductivity vary.


Conductivity list of metals

s block metals

Place Metal
1 Ag
2 Cu
3 Au
4 Al
5 Zn
6 Ni

You will see, most of the good conductors are transition metals. There are not s block metals in good conductors list. But s block metals are also conductors.



Catalyst behavior

Transition metals (3d metals) and their compounds can behave as catalysts. Alkene hydrogenation is catalyzed by Ni or Pt or Pd metals. But s block elements are not shown catalyst behavior as 3d metals.

Also 3d elements, aluminum compounds can act as catalysts. Anhydrous aluminium chloride (AlCl3) is used to benzene alkylation and chlorination as a catalyst. Aluminium is p block element.



Chemical Reactivity Characteristics of Metals

s block metals are more reactive than d block metals. From s block metals, alkali metals are much reactive than alkali earth metals .


Explanation 3d metals are less reactive than s block metals

Let's take some metals, potassium (group 1), calcium (group 2) and iron (3d metal) reactions with water.


  • Potassium reacts with water vigorously (may be with explosions) with water and produce potassium hydroxide (KOH) and hydrogen gas.
  • Calcium slowly reacts with water to produce calcium hydroxide and hydrogen gas.
  • Iron does not react either with cold or hot water.

So, it is clear that, potassium is the most reactive element in those three elements and iron is the lowest reactive element.



Reactivity with oxygen

Reaction of metals with oxygen explains the metals' reaction characteristics very nicely. Metals reacts with oxygen and produce metal oxides. When a metal exposes to the air, an oxide layer is formed on the metal.


In a oxygen stream, very reactive metals such as sodium, potassium, rubidium give peroxide and super oxide as products.



With acids

Metals except (copper, mercury, silver and gold) react with dilute acid and produce salt and hydrogen gas. As with other reagents, s block metals react very quickly with dilute acids.



References

  • Budavari, S. (ed.). The Merck Index - Encyclopedia of Chemicals, Drugs and Biologicals. Rahway, NJ: Merck and Co., Inc., 1989., p. 634
  • O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition, Whitehouse Station, NJ: Merck and Co., Inc., 2001., p. 712
  • Weast, R.C. (ed.) Handbook of Chemistry and Physics, 68th ed. Boca Raton, Florida: CRC Press Inc., 1987-1988., p. B-88


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Oxidation Numbers of Elements in Periodic Table Why alkali metals are strong reducing agents? Inorganic Chemistry Alkali metals Alkaline earth metals Chloride, bromide, iodide ions Carbonate ions Sulfate ions