Chem Unit 6 Test
What are the possible values of mℓ for an electron in a d orbital?
-2,-1,0,1,2 Since the allowed values for mℓ range from −ℓ to +ℓ, once you know the value for ℓ you know the values for mℓ.
What is the only possible value of mℓ for an electron in an s orbital?
0 Since the allowed values for mℓ range from −ℓ to +ℓ, once you know the value for ℓ you know the values for mℓ.
What is the maximum number of electrons that a d subshell can hold?
10
Give the complete ground-state electron configuration for silicon (Si).
1s^22s^22p^63s^23p^2
How many electrons can an n = 6 shell theoretically hold?
72 electrons
How many orbitals are there in the third shell (n=3)?
9 Nine orbitals (one s, three p, and five d) can hold a maximum of 18 electrons.
What is the aufbau principle?
An electron occupies the lowest-energy orbital that can receive it
Which atom in the following pair would you expect to be larger? Ba or Mg. Explain.
Ba, Atoms get larger as you go down a group.
Quantum Numbers - what do they mean?
Every electron in an atom is described by a unique set of four quantum numbers: n, ℓ, mℓ, and ms. The principal quantum number, n, identifies the shell in which the electron is found. The angular momentum quantum number, ℓ, indicates the kind of subshell. The magnetic quantum number, mℓ, distinguishes the orbitals within a subshell. The spin quantum number, ms, specifies the electron spin.
Which type of electromagnetic radiation has the greatest energy?
Gamma rays
Which atom in each of the following pairs has a larger radius? Na or K
K
Which atom in the following pair would you expect to be larger?Rh or Nb. Explain.
Nb. Atoms get smaller as you go across a period.
What is the Pauli Exclusion principle?
No two electrons in an atom can have the same set of four quantum numbers (n, ℓ, mℓ, and ms).
Quantum Number Rules
Quantum numbers can be thought of as labels for an electron. Every electron in an atom has a unique set of four quantum numbers. The principal quantum number n: - corresponds to the shell in which the electron is located, can be any integer. For example, an electron in the 2p subshell has a principal quantum number of n=2 because 2p is in the second shell. The angular momentum quantum number ℓ: - corresponds to the subshell in which the electron is located, s subshells are coded as 0, p subshells as 1, d as 2, and f as 3. For example, an electron in the 2p subshell has ℓ=1, ℓ can have integer values ranging from 0 to n−1. The magnetic quantum number mℓ: - corresponds to the orbital in which the electron is located, the three 2p orbitals can be labeled −1, 0, and 1, mℓ can have integer values ranging from −ℓ to +ℓ. The spin quantum number ms: - corresponds to the spin of the electron in the orbital, value of 1/2 means an "up" spin, −1/2 means a "down" spin
When you compare the atomic radius of silicon (Si) to that of phosphorus (P), ____.
Silicon is a larger atom than phosphorus because phosphorus has one more proton than silicon, thereby increasing the attraction for all electrons and decreasing the atomic radius.
Which atom in each of the following pairs has a larger radius? V or Ta
Ta
Atomic Radii and Effective Nuclear Charge
The atomic radius of an element can be predicted based on its periodic properties. Atomic radii increase going down a group in the periodic table, because successively larger valence-shell orbitals are occupied by electrons. Atomic radii generally decrease moving from left to right across a period because the effective nuclear charge increases.
The Bohr Equation
The electron from a hydrogen atom drops from an excited state into the ground state. When an electron drops into a lower-energy orbital, energy is released in the form of electromagnetic radiation.
Give the ground-state electron configuration for silicon (Si) using noble-gas shorthand.
[Ne]3s^23p^2
Why do elements in the 6th period have a greater atomic size than elements in the 1st period?
as you add more protons, you add more shells --> bigger size
Why do elements in the IA group of periodic table have a greater atomic size than elements in the VIIA group?
because elements in the IA group have a smaller number of protons, therefore they the nucleus is pulling less on the valence shell electrons (effective nuclear charge), thus making their atomic size greater
What are valence electrons?
electrons on the outermost shell of an atom
What is Hund's Rule?
every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.
What is the octet rule?
hi It states that elements react to form compounds that put 8 electrons in their outermost valence shell in order to achieve the identical configuration of a noble gas --> stability
What is the atomic size trend on the periodic table?
horizontal: <------- (right to left) vertical: ↓ increases top to bottom
Give the possible combinations of quantum numbers for the following orbitals. A 2p orbital
n = 2, l = 1, ml= -1,0,1
Give the possible combinations of quantum numbers for the following orbitals. A 3s orbital
n = 3, l = 0, ml= 0
Place the following elements in order of decreasing atomic size: arsenic, sulfur, neon, cesium, calcium, and phosphorus.
small to large: Ne, S, P, As, Ca, Cs
What are shielding electrons?
the electrons in between the nucleus and valence electrons - basically, all of the electrons except for the ones on the outermost shell
As an electron drops from the n=5 level to the n=2 level, what happens?
the light of one color (depending on the eV in each shell) is emitted
What is effective nuclear pull?
the pull of the nucleus on the valence shell electrons
