Question

1. Which of the following atoms would you expect to release less energy than carbon when an electron is added to its valence?

oxygen (O)

fluorine (F)

chlorine (Cl)

neon (Ne)

2. Suppose a laboratory wants to identify an unknown pure substance. The valence electrons of the substance's atoms feel an effective nuclear charge of +4. If the unknown substance has a higher electronegativity value than silicon (Si), what other characteristics would you expect the substance to exhibit?

It would have larger atomic radii than Si and higher ionization energies than Si.

It would have larger atomic radii than Si and lower ionization energies than Si.

It would have smaller atomic radii than Si and higher ionization energies than Si.

It would have smaller atomic radii than Si and lower ionization energies than Si.

3. The trend for ionization energy is a general increase from left to right across a period. However, nitrogen (N) is found to have a higher first ionization energy value than oxygen (O). Explain this exception to the general trend in terms of electron arrangements and attraction/repulsion.

4. A hydrate of Na2CO3 has a mass of 4.31 g before heating. After heating, the mass of the anhydrous compound is found to be 3.22 g. Determine the formula of the hydrate and then write out the name of the hydrate. Please show all your work for the calculations for full credit.

Answer 1

1. the element that's less electronegative than carbon

Answer 2

which would that be?

Answer 3

that would mean that the electronegativity is lower than that of carbons but all of them are higher

Answer 4

using the allen scale it says 4.789 for the electronegativity of neon

Answer 5

ok i guess i'm really not helping...let's try this instead....wouldn't you agree that more energy would be released when an electron is added to the more electronegative elements (O, F, and i believe Cl too)? if so, then neon has to be the correct choice.

Answer 6

okay thanks...can you help with the rest?

Answer 7

on 2: the effective charge is the same, so it looks like this unknown element has to be in the same group as silicon, and it is higher than silicon. what do you think this tells us about the atomic radius and ionization energy?

Answer 8

it has a larger atomic radius and lower ionization energy?

Answer 9

guess again... "higher in the same group/column", what does it tell us about the principal quantum number (n) of the valence shell?

Answer 10

im drawing a blank... is any part of my answer right?

Answer 11

okay...let's try this...say two elements, X and Y are in the same group and X is higher than Y in the group. Compared to Y, are the valence electrons of X closer or further from the nucleus?

Answer 12

closer?

Answer 13

neon

Answer 14

excuse me 0_o its oxygen

Answer 15

touseli: i agree.

when the valence electrons are closer to the nucleus, does it make the atomic radius larger or smaller?

the elements are in the same group and so the valence electrons feel the same effective nuclear charge. if the electrons are closer to the nucleus, would it cost more energy or less energy to remove them?

Answer 16

smaller?
less?

Answer 17

smaller and more...look it up in the "periodic trends" section in your book.

Answer 18

ohh okay...any others you can help with?

Answer 19

wait so its
smaller atomic radius and higher ionization energies?

Answer 20

3. However, nitrogen (N) is found to have a higher first ionization energy value than oxygen (O). Explain...

each of the p orbitals of nitrogen is singly occupied, but one of the p-orbitals of oxygen is doubly occupied. what do you think...is there more or less electron repulsion in oxygen compared to nitrogen?

Answer 21

more right?

Answer 22

i agree with you my friend...since there is more electron repulsion in oxygen (compared to the strange case of nitrogen), wouldn't you think that it'd be easier to ionize that first electron?

Answer 23

yes?

Answer 24

yes i agree! why don't you open a new question for the last one so other people can help you without having to scroll a mile?

Answer 25

okay uhm one thing

This is how i wrote my answer...

Each of the p orbitals of nitrogen is singly occupied, but one of the p-orbitals of oxygen is doubly occupied causing more electron repulsion than in nitrogen. Since there is more electron repulsion in oxygen (compared to the strange case of nitrogen), it'd be easier to ionize the first electron.

is it good or should i change some things?