Will_B123
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With Group 1 Alkali Metals the reactivity increases as we go down the group.

I have a question which says 'Explain what you see in the reaction of group 1 alkali metals'.

What could I put I was thinking of putting 'fizzes in water and gets more vigorous as we go down the group' is this acceptable? any other suggestions? Help would be greatly appreciated, thank you
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charco
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(Original post by Will_B123)
With Group 1 Alkali Metals the reactivity increases as we go down the group.

I have a question which says 'Explain what you see in the reaction of group 1 alkali metals'.

What could I put I was thinking of putting 'fizzes in water and gets more vigorous as we go down the group' is this acceptable? any other suggestions? Help would be greatly appreciated, thank you
Physical property density (mass/volume)

• Low density metals.
• Lithium floats
• Metal atoms (ions) not tightly bonded together
• Metal atoms relatively large compared to mass
• More dense descending the group


Chemical properties with water:

• Violent reaction K > Na > Li
• Hydrogen gas released (effervescence)
• Lighted splint pops
• Na, K melt
• Li maintains integrity
• K purple flame
• Na yellow flame if restrained
• Alkali solution formed (indicator)

The metals are easy to cut because the metallic bonding is weak.The strength of the bonding is a function of the number of electrons in the delocalised band and the magnitude of the charge on the ions and the size of the ions.

Explanation of reactivity towards water

Group 1 metals need only to lose 1 electron to attain a full outer shell. They can do this by giving the electron to the hydrogen ions present in water.

Reason for variation:

• loss 1e relatively easy, gets easier as electron is further away from the nucleus
• hydrogen is a flammable gas
• energetic reaction, metals have low m.p.
• less energetic reaction, Li higher m.p.
• restraint prevents energy dissipation in Na
• metal hydroxides are alkaline

Why do the metals have different reactivity?

Both physical and chemical properties can be explained in terms of the electronic structure of the individual atoms and the bulk metallic structure.
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