[kavin011]

Dear All,

    1) Why "d" group (or) Transition metals started in 3rd series of periodic table,because its located in 4th series how we can easily understand?

     2) All chemical reaction is based on Valance electron (outer shell electron) ?
     3) Am confused for Copper valance electron is it 1 (or) 2 ?
     4) Can silver reacted with oxygen ? if not why its not reacted ? silver valance electron is 2 and oxygen valence is 6,the both can reacted easily know?

Kindly advise me to understanding the above things.

[chenbeier]

1. The reason is the outer shell can carry maximum 8 Electrons. With d group wie have possibilities from 9 Scandium to 18 Zinc. In periodic table of elements you can see that the 4th series start with potassium and calcium. You can also see that almost all d elements have 2 electrons the 4s² in outer shell. Exeptions chromium and copper.
2. yes
3. copper has only one 4s because the other electron is transferred into the 3d orbital, more stable. But copper can built up Cu⁺ and Cu²⁺ compounds.
4. Yes it can.  see https://en.wikipedia.org/wiki/Silver_oxide

[pripankaj]

Why "d" group (or) Transition metals started in 3rd series of periodic table,because its located in 4th series how we can easily understand?

[Borek]

Why "d" group (or) Transition metals started in 3rd series of periodic table,because its located in 4th series how we can easily understand?

Do you know the Aufbau principle?

[Enthalpy]

2) All chemical reaction is based on valence electron (outer shell electron)?

In transition elements, several shells or subshells have energies close to an other, so they can participate more or less to chemical bonds.

That's no so exceptional. Carbon too can has the valences 2 or 4, despite the 2s electrons are more strongly bound than the 2p.

The 2 or 4 electrons from carbon come from the same level, as opposed to transition elements. But the only reason is that the sublevels have energies in a sequence not trivial to predict nor understand, for which our naming convention isn't adequate. And anyway, the sequence changes with orbital filling, so no naming convention would be good.

4) Can silver react with oxygen ? if not why its not reacted ? silver valence electron is 2 and oxygen valence is 6,the both can reacted easily know?

This reasoning would be perfect if reacting lone atoms, but this happens seldom. Usually, molecules react, and these must be broken to create new molecules.

While silver does tarnish in air, especially if helped by other molecules, gold for instance does not. Metallic gold is a very stable molecule.

The ability to form bond and possibly release energy doesn't suffice to make predictions. For instance stainless steel should transform in a heap of rust based on the heat of reaction, but the layer of chromium oxide at its surface stops the oxygen.