H2 Chem: IE of elements

anpanman SG

I was told that the atomic radius of an atom is determined by the no. of electron shells, but it can also be determined by size of nuclear charge and the extent of shielding by inner electrons.

May I know how the extent of shielding by inner electrons affect the atomic radius? Is it more shielding, larger atomic radius (due to repulsion of inner electrons) and hence lower IE?

2. Is there any difference in determining the 2nd and 1st IE of elements? How do I accurately determine these? Sometimes questions told us to examine the 2nd IE of elements and I actually used the same explanation for such a case. I guess I need more clarification on this.

That aside, yes, I was told to sketch the graph of the 1st and 2nd IE from Na to Ar so I need this absic knowledge.

3.For a compound like CO3 2- which has mass no. of 13, if I want to determine the no. of electrons, protons and neutrons, do I consider each factor element by element?

I mean like,

C has 6 e- and O has 8 e- so O3 has 24e-. Total e- is 30. With a charge of -2, it will have gained 2 e-, so total e- for this compound is 32?

Do I consider them like this? Do explain that for proton and neutrons too. Hmm, yeah, have a prob with determining the total no. of neutrons in such a compound.

Thanks

UltimaOnline SG

I was told that the atomic radius of an atom is determined by the no. of electron shells, but it can also be determined by size of nuclear charge and the extent of shielding by inner electrons.

May I know how the extent of shielding by inner electrons affect the atomic radius? Is it more shielding, larger atomic radius (due to repulsion of inner electrons) and hence lower IE?

That aside, yes, I was told to sketch the graph of the 1st and 2nd IE from Na to Ar so I need this absic knowledge.

3.For a compound like CO3 2- which has mass no. of 13, if I want to determine the no. of electrons, protons and neutrons, do I consider each factor element by element?

I mean like,

C has 6 e- and O has 8 e- so O3 has 24e-. Total e- is 30. With a charge of -2, it will have gained 2 e-, so total e- for this compound is 32?

Do I consider them like this? Do explain that for proton and neutrons too. Hmm, yeah, have a prob with determining the total no. of neutrons in such a compound.

Thanks

1. Yes, you're correct.

2. The 2nd IE involves removing an electron from a unipositive cation, and is hence significantly more endogernic than the 1st IE. Note that there are anomalies in the trends of 2nd IEs that paralllel the 1st IE, eg. 2nd IE of Si lower than 2nd IE of Al, for the same reason that the 1st IE of Al is lower than that of Mg.

You're not expected to be able to "accurate determine" or quantitatively predict the 2nd, 3rd, 4th IEs; you're expected to refer to these values in the Data Booklet for all exams, including for the sketching of graphs for the 1st, 2nd, 3rd, 4th IEs.

3. Yes, your approach is correct. As for neutrons, you'll utilize the mass numbers given in the periodic table, which is a weighted average of the masses of the isotopes for each element.

However, you're also expected to be able to draw ions such as the carbonate(IV) ion, CO3(2-), including illustrating how many lone pairs and bond pairs are present in the valence shells of each atom.

anpanman SG

Thanks UltimaOnline, appreciate your advice!

I have one question I'm in doubt of.

Identify this element.

An excited state of this element has the electron configuration [Kr]5s2 4d6 5p2 6s1

I do realize that the written order is wrong. But how can I go about identifying this element? I mean in our school we were only taught that during excitement, the paired electrons in 1 subshell will see 1 of its electron promoted to higher energy level.

What happens if it involves TWO paired electrons? After we transfer 1 of the paired electron up the next energy level (eg. to a 4s subshell), do we still transfer the 2nd electron to the 4s subshell since it can accomdate two electrons? Or do we move it to the 4p subshell so the electron does not have to be paired again?

As question 2 in the earlier post, you mean we can ignore the mass no. 13 given in the question?

thanks!

UltimaOnline SG

Thanks UltimaOnline, appreciate your advice!

I have one question I'm in doubt of.

Identify this element.

An excited state of this element has the electron configuration [Kr]5s2 4d6 5p2 6s1

As question 2 in the earlier post, you mean we can ignore the mass no. 13 given in the question?

thanks!

The element is Ag. The question implies this is an atom, not ion. Hence, adding up the electrons gives you the proton number.

You cannot determine the electronic configuration of an excited states (there are too many possibilities, and the specifics of these are not relevant to the H2 syllabus). The configuration of excited states must be given to you in the question. All you need to do (as far as your syllabus is concerned), is recognize, "ahhh, it's excited! I'm excited! Chem is exciting!"

As for qn 2, the question is erroneous if it says the mass no. of the ion is 13. But if it refers to C, then use C-13 as the isotope present (to calculate total neutrons in ion), instead of C-12, the more common isotope.