CHEMISTRY COMMUNITY

Adela Henry 1I

Oh, I see. Thank you guys for your help!

Adela Henry 1I

This is what I did.

Adela Henry 1I

Hi, for question 2 I had to find the most stable lewis structure for TiCl4. I thought I had did it right because of the formal charges but it was wrong. Could someone please explain the answer?
Thanks

Adela Henry 1I

That is correct. When looking at dipole moments you need to consider the shape with regard to the effect lone pairs have on it. The lone pairs push atoms closer together and thus not all dipole moments will cancel out depending on the structure.

Adela Henry 1I

A smaller bond angle means that it has less of a chance of canceling each other out. When the bond angles are really small they go in practically the same direction meaning that the cancellation between the two is really small compared to larger bond angles where they could partially cancel each oth...

Adela Henry 1I

When you draw out the lewis structure, there are 2 single bonds between the Cl and the O atoms. O-Cl-O. There is also a lone pair of electrons around the Cl atom. This makes 3 regions of electron density meaning that the shape is trigonal pyramidal based on the arrangement of electrons. When conside...

Adela Henry 1I

Bond angles will change because double and triple bonds have higher electron concentrations compared to single bonds which leads to electron repulsion, thus affecting the angles.

Adela Henry 1I

For this question I started out by finding the element the given configuration led to. From there since it is a 3+ ion, that meant that 3 electrons were subtracted from the configuration so I added them back which meant first adding back the 2 in the s-orbital and then one in the d-orbital giving th...

Adela Henry 1I

That is correct. A structure with a lower formal charge is more likely to contribute to a resonance structure.

Adela Henry 1I

This question from the midterm was number 2.27 from the homework.

Adela Henry 1I

Generally you would look at the information provided in the question. For the values given that you will use, whichever one has the lowest number of sig figs is the number of sig figs your answer should have.

Adela Henry 1I

Basically the maximum positive and negative oxidation number is the maximum number of electrons the element has to gain or lose to reach the next noble gas. Positive = electrons lost. Negative = electrons gained.

Adela Henry 1I

Most likely yes because finding the formal charge helps to draw the most stable Lewis structure of the molecule.

Adela Henry 1I

I don't fully know why that is but if it is any help, on the list of problems to do it said to omit part d from 45. We probably won't have a question like that on the midterm.

Adela Henry 1I

If the electron configuration is equal to a noble gas then you should use the one in the row above it and then write out the rest of the electron configuration. I think Dr. Lavelle would prefer this instead of just writing [Ar] because it shows that you understand how to write an electron configurat...

Adela Henry 1I

There would be 2 unpaired electrons because the p-orbital can hold 6 electrons total. You would first begin by putting the 3 electrons as unpaired but then there is still 1 electron left which you would place with one of the first 3 single electrons. Thus there would be 1 pair and 2 unpaired electro...

Adela Henry 1I

Atomic radii decrease across a period and since P3- appears first it has the greatest atomic radii and S2- and Cl- appear after it respectively on the periodic table meaning that their atomic radii are less than it. Therefore, since it asks for increasing atomic order it would be Cl- < S2- < P3- I d...

Adela Henry 1I

They should provide you with that information by giving you the element such as K+ or N^2- An element with a + is a cation (and thus you take away electrons) and an element with a - is an anion (so you add electrons). So two elements when in the ion form could have the same electron configuration bu...

Adela Henry 1I

ms=+1/2 just means that the electron is spinning up whereas ms=-1/2 means that the electron is spinning down

Adela Henry 1I

Could someone explain how to do #7 from test 2
Thanks

Adela Henry 1I

DeBroglie's equation calculates the wavelength of any particle with wavelike properties and that have mass
lambda=Plack's constant(h)/(mass*velocity)

Adela Henry 1I

The formula is explained a little more in section 1.3 Atomic Spectra in the book.
R in the equation is Rydberg's constant and the n's are the lines (different quantum levels) on the spectrum you start at subtracted from the one you go to.
Hope this helps

Adela Henry 1I

0.09 would have 1 sig fig because the zeros come before the 9.
0.0900 would have 3 sig figs because there are 2 trailing zeros after the 9. the two zeros before the 9 are not counted as sig figs.

Adela Henry 1I

It depends on where they fall in relation to numbers that are 1 or greater.
if the number is 0.00031 there are only 2 sig figs
if the number is 300001 then there are 6 sig figs
as far as applying this with scientific notation 0.00031 becomes 3.1x10^-4 and still has 2 sig figs
Hope this helps!

Adela Henry 1I

It usually depends on what information is given in the question that I use to determine what equation to use. Wavelength c=v x and E=hv for energy of light. Use both when it is the ejection of an electron.

Adela Henry 1I

For our purposes right now I don't think the order matters, but later on in the course it might become something to pay attention to. I usually remember the order with CHNOPS for the elements that are used the most. Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfer.
Hope this helps!

Adela Henry 1I

I'm pretty sure we don't actually have to know anything about them for this course. They were only mentioned to show that unlike atoms and molecules, there is something that can absorb or emit 'all' frequencies. It was just used as a comparison.

Adela Henry 1I

If you only want 1 sig fig then you would round up to 1.
You don't have to put a decimal after the 1 because it is one sig fig without it but you can put it if you want to.
Hope this helps

Adela Henry 1I

Rounding for answers depends on the individual problem and its significant figures in the question. If the question has only 1 sig fig than rounding to 3 is fine but it it has 2 sig figs than you should leave it as 2.8

Adela Henry 1I

Frequency and cycle are the same thing because 1 cycle per second is called a Hertz which is the unit used for frequency.

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