Chemistry 001A Chapter 3 B

What quantum numbers specify these subshells?

1s: n=1, l=0 4p: n=4, l=1(since its in p-orbital) 4d: n=4, l=2(since its in d-orbital)

The principal quantum number, n, describes the energy level of a particular orbital as a function of the distance from the center of the nucleus. Additional quantum numbers exist to quantify the other characteristics of the electron. The angular momentum quantum number (ℓ), the magnetic quantum number (mℓ), and the spin quantum number (ms) have strict rules which govern the possible values. Identify allowable combinations of quantum numbers for an electron. Select all that apply.

Answer: n=5, l=3, ml=-1, ms=-1/2 n=3, l=0, ml=0, ms=-1/2 Incorrect: n=2, l=0, ml=0, ms=-1 n=3, l=-1, ml=0, ms=+1/2 n=4, l=4, ml=1, ms=-1/2 n=4, l=2, ml=3, ms=+1/2

What element forms an ion with an electronic configuration of [Xe] and a -2 charge?

Barium, if it loses two electrons, will have the electronic configuration of [Xe] when it loses the 6s2 electrons, but it will be a +2 cation, not an anion. However, Tellurium can adopt a -2 charge, and when it picks up two electrons, it fills the 5p shell with six electrons, so it will have the electronic configuration of [Xe].

Which of the following electron configurations of neutral atom represent the excited state:

Correct: 1s^2 2s^2 3s^2 3p^6 3d^2; 2s^2; [Xe]6s^2 4f^1. All of them skip an energy level. Incorrect: [Kr]5s^14d^5; [Ar]4s^2 3d^3

Determine the element of the lowest atomic number that contains a half-filled d-subshell in the groudn state:

Cr since it is 4s1 and 5d^5 (special case just like copper)

First Ionization Energy

Energy it takes to remove one electron in an atom. Look at shells to see stability. (Look at electron orbitals) Full=more stable than non full.

identify the neutral element represented by this excited-state electron configuration, then write the ground-state electron configuration for that element

Excited state: 1s^2,2s^2,2p^1,3s^1 Element Symbol: C Ground state: 1s^2, 2s^2, 2p^2 Look at electrons to figure out element.

if Ml=2 what can you say about l?

For ground state electrons ... if L = 0 (s-sublevel) then mL = 0 if L = 1 (p-sublevel) then mL has values of -1, 0,+1 if L = 2 (d-sublevel) then mL has values of -2, -1, 0, +1, +2 if L = 3 (f-sublevel) then mL has values of -3, -2, -1, 0, +1, +2, +3 Therefore, if mL = 2 then it could be in the d or f sublevel, so L would be 2 or 3.

A space probe identifies a new element in a sample collected from an asteroid. Successive ionization energies (in attojoules per atom) for the new element are shown below

I1=.507 I2=1.017 I3=4.108 I4=5.074 I5=6.147 I6=7.903 I7=8.294 Belong to 2(2A) because of of the increase in stability from I2 to I3.

What information is needed to determine the general shape of an orbital

L

Rank these ions according to ionic radius

Largest Radius: P^3-, S^2-, Cl^-, K^+, Ca^2+ Because more protons attracts more electrons

What information is needed to determine the orientation of an orbital?

Ml

What information is most important in determining the size of an orbital?

N

If l=1 what can you deduce about n?

N >1 since if L=1 1=(n-1) 2=n

What information is needed to determine the energy of an electron in a many-electron atom?

N and L

Rank the following elements by effective nuclear charge, Zeff, for a valence electron:

Z* = Z - S Z is the number of protons in the nucleus and S is the average number of electrons between the nucleus and the electron in question. If we are looking at the 3s Obital, the "S" will be the number of electrons in the orbitals in the 1s,2s,2p orbitals. *this number will remain constant as the elements mentioned are all below Neon. Cl>S>P>Al>Na

How many electrons does a Fe atom have in its 3d subshell? How many of those electrons are unpaired?

a) 6 3d electrons b)4 unpaired electrons: 1_1 (1_ 1_ 1_ 1_) 4 left.

Predict the groudn state electron configuration of the following ions. Write your answers in abbreviated form, that is, beginning with a noble gas in brackets.

a) Ru^2+=[Kr]5s^2 4d^6---> [Kr]4d^6 b)W^3+=[Xe]6s^2 4f^15 5d^3--->[Xe]4f^14 5d^3

For each electron in a ground-state Be atom, select the set of quantum numbers that represents it

a)n=2,l=0,ml=0,ms=-1/2 b)n=2,l=0,ml=0,ms=+1/2 c)n=1,l=0,ml=0,ms=-1/2 d)n=1,l=0,ml=0,ms=+1/2 because Be is in the S-orbital, making l and ml=0

1. principal quantum number n = 1, 2, . . . (as on Earth); 2. angular momentum quantum number ℓ = 0, 1, 2,. . . , n - 1 (as on Earth); 3. magnetic quantum number mℓ = 0, 1, 2, . . . , ℓ (only positive integers up to and including ℓ are allowed); 4. spin quantum number ms = -1, 0, 1 (that is, three allowed values of spin). a) assuming that the Pauli exclusion principle remains valid, what is the maximum number of electron that can populate a given orbital? b): electronic configuration of atomic number 8 c) What is the atomic number of the second noble gas?

a)the orbital is defined by n,L, mL.. so you could have (n, L, mL, -1), (n, L,mL, 0) and (n,L,mL, +1)... ie... 3 electrons for any given orbital b)Atomic number=8, 8 electrons and since each shell has 3 electrons in each orbitals, then 1s^3,2s^3,2p^2 C)Need to fill n=2: so the first noble gas has full n=1 shell, 1s^3. The second noble gas has full n=1 and n=2 shells. 12 electrons: 1s=111,2s=111,2p=111,111. Follow the order: (1, 0, 0, +1) (1, 0, 0, 0) (1, 0, 0, -1)... .. .<----- ideal gas!... 3 electrons.. so 3 protons and atomic # = 3 (2, 0, 0, +1) (2, 0, 0, 0) (2, 0, 0, -1) (2, 1, 0, +1) (2, 1, 1, +1) (2, 1, 0, 0) (2, 1, 1, 0) (2, 1, 0, -1) (2, 1, 1, -1).. .. .<----- 2nd ideal gas...12 e's.. so 12 p's and atomic # = 12

How many electrons in an atom could have these sets of quantum numbers?

n=3: 3s,3d,3p. (1 orbital+3 orbital +5 orbital)2.=18 electrons total in each orbital n=4, l=1: P orbital:= 6 electrons n=7,l=2,ml=-1:1 orbital b/c of ml=-1= 2 electrons.