The instructor took a piece of Li from its storage and smudge off the oil with absorptive paper. The Li is placed on a white tile and a little piece is cut off with a scalpel.
The instructor dropped a little piece of Li into H2O in the trough.
Observations of what happened to lithium were noted down the tabular array.
The instructor placed a lit splint merely above the Li in the trough.
Observations of what happened when the splint got near the Li were besides noted down.
The instructor dipped a piece of full scope index paper into the trough.
The coloring material of the full scope index paper was noted down.
The instructor repeated stairss 3 to 8 utilizing another trough for Na so K.
metal
Appearance
Observations of metal in H2O
Consequence of lighted splint
Coloring material of full scope index paper
Lithium
Silvery white
Reacts easy, effervescence- H2 given off, floats and easy moves one side of the trough to the other
Squeaky dad sound
Purple-indicating solution is alkalic and OH- ions present
Sodium
Silvery white
Reacts smartly. Floats and moves faster than Li. Effervescence- H2 given off, readily combusts, metal form turned to ball
Squeaky dad sound
Darker purple
Potassium
Silvery white/grey
More vigorous reaction than Na. Floats, moves faster than Na. Purple fire
Chemical reaction is so vigorous that H2 released already combusts without the demand for a fire
Much darker purple
Hydrogen gas is produced when the metals reacted with H2O.
Hydroxide ( OH- ) ions which make the solution acidic.
Sodium + H2O i? Na hydrated oxide + H2O + H
Traveling down the group, the metals become more reactive and so when they are placed in H2O, the reaction becomes more vigorous. When Li is placed in H2O, we see effervescence and that it floats and moves from one side of the container to the other. The gas given off is hydrogen and can be tested utilizing a lighted splint which will start to corroborate the presence of this gas.
When a piece of Na metal is placed in H2O, we see that its reaction is merely similar Li except it is more vigorous. The reaction occurs quicker, as the piece of Na floats and moves on the surface of the H2O faster. A faster reaction means that H is given off at a faster rate which is seen by the effervescence. Sometimes the piece of sodium visible radiations on fire as the H given off combusts without the demand for a lit splint. Other times, the piece of Na does non light until you bring a fire near by to prove for the H.
Responsiveness of the group 1 elements: Potassium & gt ; Sodium & gt ; Li
The general tendency is that responsiveness increases down the group, so Rb will be more reactive than K to a degree where it will detonate and cesium is more reactive than Rb. Francium may respond to fast in air before it could even be put in the H2O.
“ Francium is the least stable of the of course occurring elements: its most stable isotope, francium-223, has a maximal half life of merely 22 proceedingss. In contrast, At, the second-least stable of course happening component, has a maximal half life of 8.5 hours. ” ( 1 ) It continuously signifiers and decays into At, Ra, and Rn. Equally small as 20-30g exists at any given clip throughout the Earth ‘s crust. Its unstable nature is expected when looking at the other elements in the same group. The tendency of increasing responsiveness down the group, as shown above, helps us predict this for Fr. Because it has merely one negatron in its out shell and this negatron experiences really small attractive force from the karyons due to the big distance between them and the high sum of showing or shielding. In fact, Fr can derive an negatron or lose one or two to organize Ra, Rn and At severally. This shows the radioactive nature of the component and because it is radioactive, it is really harmful for animate beings and the environment.
In the reaction between the group 1 elements and H2O, H gas is produced
The H came from the H2O. Water molecule dissociates.
At the terminal of the reaction, the elements have wholly reacted to organize the merchandise, which are the hydroxide metal in aqueous solution and the H gas.
Component
Responsiveness
Gas
Floats
Dissolves
Lithium
Reasonably reactive
effervescence- H2 given off-squeaky dad when tested with fire
floats and easy moves one side of the trough to the other
No
Sodium
Strong
Effervescence- H2 given off, sometimes readily combusts
Floats and moves faster than Li.
No
Potassium
Very strong
Effervescence- H2 given off, readily combusts
Floats, moves faster than Na.
No
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Characteristic belongingss of Group 1 elements
They are soft metals and can be cut with a knife. Potassium is softer than Na which is softer than Li. Though Li is harder than both Na and K, it is soft plenty to be cut with knife. Newly cut surfaces are reflecting, but acquire covered with a bed of oxide or carbonate when kept in contact with air.
They have low densenesss: Li, Na, and K all float on H2O. Rubidium and cesium have higher denseness than H2O and sink. Lithium is the lightest metal known.
They have low thaw and boiling points
They have colorless compounds but when heated under a Bunsen burner, the fire will be coloured.
Down the group:
Responsiveness additions
Hydrogen gas given off when metal is inserted into H2O becomes more readily combustible.
Melting and boiling points lessening
First ionization energy lessening
Electronegativity lessenings
Q12.
The aqueous solutions are all strongly alkalic ( hence the name of this Group ) and hence unsafe to manage.
Q13. Lithium + H2O i? Li hydrated oxide + H
Sodium + H2O i? Na hydrated oxide + H
Potassium + H2O i? K hydrated oxide + H
Q14. 2Li ( s ) + 2H2O ( cubic decimeter ) i? 2LiOH ( aq ) + H2 ( g )
2Na ( s ) + 2H2O ( cubic decimeter ) i? 2NaOH ( aq ) + H2 ( g )
2K ( s ) + 2H2O ( cubic decimeter ) i? 2KOH ( aq ) + H2 ( g )
Q15. Sodium hydrated oxide ( NaOH ) is an base
Q16. Traveling down group 1 elements, the thaw and boiling points lessening but the denseness additions.
The thaw and boiling points are determined by the attractive force between the atoms in the metal. In the instance of group 1 metals, this attractive force is metallic adhering. Metallic bonding is the attractive force between the delocalised negatrons and the positive karyon. The stronger this attractive force is in an component, the stronger the metallic bonding will be. Traveling down the group 1 elements, the radius of the atoms additions, so the distance between the delocalised negatrons and the nuclei additions ; this reduces the strength of the attractive force between them.
Although the atomic charge additions down the group, the showing consequence besides increases so the delocalised negatrons do non see the increased drawing power of the karyon. So overall, merely the atomic radius is a altering factor down the group, doing the bond to go weaker and so less energy is required to interrupt it and divide the atoms.
The denseness of the group 1 elements depends on the atomic radius and mass of the component. The larger the mass figure of an atom, the higher the denseness and the larger the radius of the atom the lower the denseness ( because the weight is being spread out cut downing the downward force ) . Traveling down the group, the mass figure additions, so a certain figure of Na atoms will weigh more than the same figure of Li atoms ; nevertheless, the addition in mass figure besides means an addition in atomic radii ( because more negatrons ) , so 1 cm3 can pack more Li atoms than Na atoms. Overall, the addition in mass figure has a bigger consequence than the addition in atomic radii, so the denseness additions.
Q17. When heating group 1 compounds a alteration in the fire coloring material is observed. This happens because the metal ions in the compound absorb heat from the fire doing the negatrons to derive energy and go aroused. When excited, they jump into any empty orbital at higher degrees. For illustration, if the compound in inquiry contains lithium ions, the electronic constellation for Li in this unexcited province is: 1s22s2. When the negatrons are excited, they can leap into the 6s, 3d, 5p or whatever depending on how much energy a peculiar negatron absorbed from the fire. Because the negatrons are at this higher and energetically unstable degree, they tend to leap back to their original orbital but non needfully all in one spell. So, if the negatrons are at the 6th degree, they may leap back to the 4th degree so to the 2nd degree. The negatrons may even leap back from the 6th to 2nd degree all in one spell and this depends on the metal ion in inquiry. Every clip the negatrons jump from a high energy degree to a lower energy degree, they give out energy as light energy. The varied leaps produce a spectrum of colored lines which combine to give us the coloring material we see for a specific metal ion. The sizes of the negatron leaps vary from one metal ion to the other hence different sums of energy are released in the signifier of visible radiation. This produces different combinations of visible radiation to be emitted ; hence different fire colorss are seen.
18. Traveling down the group the ionization energy values of the elements lessening as less energy is required to take the outer negatron of a gaseous atom of an component. Ionisation energy depends on:
Charge of nucleus- the karyon of an atom is positively charged because each proton in the karyon carries a 1+ charge. The negatrons which surround the karyons have a 1- charge and are attracted and to the protons in the karyon. This keeps the negatrons is their orbitals and it would necessitate energy to take them. The higher the atomic charge is ( because many protons are present ) , the stronger the attractive force between the negatrons and the karyon will go, so the negatrons are non easy removed.
Nuclear charge- The more protons there are in the karyon, the more positively charged the karyon is, and the more strongly negatrons are attracted to it.
Distance from the nucleus- Attraction falls off really quickly with distance. An negatron stopping point to the karyon will be much more strongly attracted than one farther off. So an atom with many negatrons, the outer negatron will be far off from nucleus and easier to take.
Q19. The group 1 elements are cut downing agents as they give an negatron in a reaction. The tendency down the group 1 elements is that their cut downing power additions as shown by their addition in responsiveness with H2O.
Q20.
Component responding with O
Possible oxides
Chemical belongingss
M.P. ( K )
B.P. ( K )
Acid/Base
Lithium
Li2O
1987
–
Base
Li2O2
1250
–
Base
Sodium
NaO2
–
–
strongly basic
Na2O
1548
–
strongly basic
Na2O2
733
930
strongly basic
Potassium
KO2
653
–
Base
K2O
623
–
Base
K2O2
763
–
Base
Rubidium
Rb2O
673
–
Base
Rb2O2
873
–
Base
RbO2
685
–
Base
Cesium
Cs2O
763
673
Base
CsO2
873
–
Base
Francium
–
–
–
–
Lithium
When Li undergoes burning in O, the major merchandise formed from the reaction is lithium oxide:
Lithium peroxide is another possible merchandise to be formed from the reaction but in smaller sums:
Sodium
