My OperaGroup 1 Metals - Alkali
Sunday, February 28, 2010 1:35:48 AM
Let's watch our News Channel for today...... (hello Mr.teo, sorry for this inconvinience,we tried to upload the video but it cannot; so can you please refer to the video inside the thumbdrive we gave you. Thank you)
Do you feel anything relating to Chemistry here???? Let's refer to our understanding questions to know more...
Do you feel anything relating to Chemistry here???? Let's refer to our understanding questions to know more...
At the scene at the car accident, explain why Mr. So Di-Um (Na) got less injures than Mr. Po-ta Ssium (K) even though both of them experienced the same accident. Use your knowledge of Group I metals’ physical properties to answer.[/FONT]
A[/I][/B]: Even with the same force applied, Mr. Sodium suffered less injury, and in terms of physical properties of Group I’s metals, Na is actually harder than K. This is because Na has a smaller atomic radius which results in shorter metallic bond between Na atoms compared to that of K. These shorter bonds require more force applied to overcome, so Na is harder than K. [/I]
Under the high temperature of the fire (assumed to be 350.0 K), why is it that only Mr. Po-ta Ssium was melted, not Mr So Di-Um? Use your knowledge of group I metals’ physical properties in your answer.
A[/I][/B]: At the same temperature (approximately 350.0K), since Mr Potassium melted while Mr Sodium did not, it shows us that Potassium has lower melting point compared to Sodium. It is because Potassium atoms have larger atomic radius, which results in longer metallic bonds between metal atoms. The longer the bond is, the weaker it is, so this longer bond between Potassium atoms requires less energy to overcome and break compared to that of Sodium. Therefore, it’s easier to melt Potassium, which means Potassium has lower melting point compared to Sodium’s. It goes the same for boiling point. [/FONT]
At the scene at the factory, why is it that Mr. Li Thium (Li) managed to float and survive while Mr. Rubidium (Rb) did not? Use your knowledge of group I metals’ density properties in your answer.
A[/I][/B]: Since Mr. Lithium managed to float while Mr. Rubidium sank, it shows that Rb is denser than Li. This is mainly because of the difference in atomic radius of Rb and Li atoms. Rb has larger radius compared to Li, so Rb atom’s volume is larger than Li’s. Down the group, mass increases, so Rb has a bigger mass than Li. Since density = mass/volume, we can see that Rb’s density is greater than that of Li. If we calculate out the densities, we can find that Rb’s density is higher than that of water while Li’s is lower, supporting the fact that Rb sinks and Li floats.[/FONT]
The CCTV showed the “struggling” effort of Mr. Lithium and Mr. Rubidium, but it seems that Mr. Rubidium struggled much more. How does this “struggle” show the level of “reactivity” and ability of Li and Rb to be reducing agents?
A[/I][/B]:In this case, “struggling” actually represents the reactivity of the metals: the more struggling there is, the more vigorously the metals react with water. This reactivity of group 1 metals is based on the ability to give/lose electrons of atoms of different elements. They have the same number of valence electrons, but Li atoms have 1 less electron shell, so nuclear charge of Li atom (Nuclear Charge- the force of attraction between valence electrons and positively-charged nucleus) is larger. This means that:
o Li atoms have lesser tendency to lose electrons compared to that of Rubidium, so Li atoms are less powerful reagents than Rubidium atoms.
o Li atoms are less stable; hence Li atoms are more reactive than Rubidium. [/FONT]
