Question 4(Multiple Choice Worth 4 points) (02.05 LC)

Which quantum number describes the orientation of an orbital within a sublevel?

Spin quantum number

Principal quantum number

Magnetic quantum number

Angular momentum quantum number

The quantum number that describes the orientation of an orbital within a sublevel is the magnetic quantum number.

Explanation:

There are four quantum numbers in chemistry. These are the principal quantum number, the angular momentum quantum number, the magnetic quantum number, and the spin quantum number. These all follow these three foundational rules in chemistry.

The Pauli exclusion principle states that if two electrons inhabit the same orbital, they will spin in different directions.

Hund's rule states that if an orbital does not have an electron, an electron will need to fill it first before any of the other orbitals can have two electrons of differing spins.

The Aufbau principle states that all electrons will fill orbitals in an orderly fashion based on the quantum numbers.  An attachment is included of this fill order for your reference.

The four quantum numbers for chemistry are:

The principal quantum number describes the sublevel in which the orbital is located. This occurs at n = 1, 2, 3, etc. all the way to 7.

The angular momentum quantum number describes the orbital that an electron fills. It will refer to the shape and the type of orbital.  

The magnetic quantum number refers to the orientation of an orbital. Based on the angular momentum quantum number, there can be 1, 3, 5, or 7 orientations.

The spin quantum number refers to the Pauli exclusion principle. This number is assigned a negative or positive based on the orientation of the electron.

Therefore, because the magnetic quantum number is the one that refers to the orientation of the orbital, this is our answer.

C.  Magnetic quantum number

Explanation:

The principal quantum number defines the general value of the electronic energy. The angular momentum quantum number determines the shape of the orbital. And the magnetic quantum number specifies orientation of the orbital in space.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.