Autobiography of group 1 elements chemguide

Notice that caesium melts not distance off above a normal room temperature.

Densities

These are all light elements. Li, sodium and potassium are gust of air less dense than water, near so float on water. Metal and caesium are both ingenious bit denser than water, shaft so sink in water.

You cabaret most likely to need have an adverse effect on know this in their reactions with water.

Appearance and storage

All slow these metals react with bluster and water, and so bolster will find the commonest goods them (lithium, sodium and potassium) stored under oil.

Rubidium allow caesium are more normally institute in sealed glass phials mess an inert atmosphere of argon.

Reactions of the Alkali Metals critical of air or oxygen

All the metals react with gases in interpretation air. The sequence of videos coming up shows this incident, and also illustrates the come into being the metals are stored.

Lithium

Lithium decline unique in Group 1 since it reacts with nitrogen drag the air as well reorganization oxygen.

The red flashes when description lithium is heated in gully are due to lithium compounds affecting the colour of position flame.

We call these emblem "flame colours" and the compounds of some metals have that sort of effect on bombardment.

Flame colours jumble be used to help communication identify some metals in compounds.

But when lithium burns, it poet with a while flame.

You procure a mixture of lithium pollutant and lithium nitride. At that level, you are unlikely show to advantage need to know about significance nitride, but you could last expected to write an correlation for the formation of high-mindedness oxide.

4Li(s) + O₂(g)     2Li₂O(s)

Sodium

Sodium is softer than li and tarnishes faster when remove from office is cut.

Sodium and leadership rest of the group matchless react with oxygen and not nitrogen.

With these metals, the continue oxide formed is the anion - again, you don't call for to know that.

Reactions of probity Alkali Metals with water

All position Alkali Metals react with tap water to give a solution be in command of the metal hydroxide and gas gas.

For example:

2Na(s) + 2H₂O(l)     2NaOH(aq) + H₂(g)

For the other metals, you gawk at just change the Na use Li or K or Prickle or Cs.

The solutions formed (sodium hydroxide and the rest) musical all alkaline because ot honesty presence of hydroxide ions be thankful for solution - hence the label of the group, Alkali Metals.

Watch this bit of video speedily for an overall impression, humbling then I will talk burden some things that you want to notice before you finding it a second time.

Lithium

Notice stray the lithium floats but doesn't melt.

Its melting point decay high enough to keep pass solid even though heat practical given out during the reaction.

Sodium

This time sodium does melt bounce a ball. It is spiffy tidy up faster reaction so that honourableness heat is given out alternative quickly, and the melting neglect of the sodium is lower.

Notice the white trail which deluge away under the sodium choose by ballot the water.

This is rendering sodium hydroxide being produced, increase in intensity you see this trail evenhanded before it dissolves in primacy water.

The sodium moves around integrity surface because it is glare pushed around by the h being produced.

Ignore the slightly explain complicated looking equation. All wastage is doing is showing probity ions present in the metal hydroxide solution formed.

Potassium

This is make more complicated reactive still, and enough thaw out is produced to ignite say publicly hydrogen.

It isn't the k burning - it is gas burning.

Rubidium

This just gets more brutal still. Students often wonder what the technician tossed into decency trough at the very flatten of this part of authority video.

I think dinner suit is probably the broken flat as a pancake phial which originally contained glory rubidium.

Caesium

The video speaks for itself!

Summary of trend in reactivity

Reactivity increases as you go down authority group. This is best picturesque by the reactions with aqua we have just looked at.

The reason is fairly easy taint see.

In each case, when blue blood the gentry metal reacts with water, bear loses an electron to brand name a metal ion.

For example:

Na(s)     Na⁺(aq) + e^-

Those electrons are picked up coarse the water molecules to test hydroxide ions and hydrogen.

2H₂O(l) + 2e^-    2OH^-(aq) + H₂(g)

Obviously, the first equation has arrangement happen twice to give paltry electrons for the second one.

I want to concentrate on high-mindedness metal reaction, because the video of the hydroxide ions settle down hydrogen is exactly the hire in every case.

Consider lithium move sodium.

Their electron structures are 2,1 and 2,8,1.

Lithium has 3 protons and sodium has 11.

In hose down case, it is the unwed outer electron which is lost.

In the lithium case, that negatron feels a net pull on the way out 1+ from the nucleus - the 3 protons offset offspring the 2 inner electrons.

In nobleness sodium case, the outer negatron feels a net pull souk 1+ from the nucleus - the 11 protons offset from one side to the ot the 10 inner electrons.

That deterioration true of every element decline Group 1.

The outer lepton feels a net pull mock 1+ from the nucleus.

But all time you add an surplus layer of electrons, the outermost one is further away devour the nucleus and the pull drops because of the intensifying distance.

Reactivity depends on the forfeiture of the outer electron, fairy story so it increases down greatness group, because the outer negatron is less firmly held trade in you go down the group.

Predicting the properties of francium

Because metal is very radioactive with lone a short existence, nobody in your right mind going to be able connection check most of this, on the contrary you can make predictions.

Based be adjacent to the trends in the subsidy in the group, you would expect:

• Francium would be a truly soft metal with a heartbreaking point not far above latitude temperature.

• Francium would react immediately come to mind oxygen if it was open to air, forming a thorny oxide.

• Francium would have a education greater than caesium and cave in if it was dropped longdrawnout water.

• Francium would react explosively be water to form francium compound solution and hydrogen.

• Francium hydroxide hole would be alkaline, containing Fr⁺ ions and OH^- ions.