Ib Chemistry Hl Topic 12

1. Explain how evidence from first ionization energies across periods accounts for the existence of main energy levels and sub-levels in atoms.

Ionisation energy: The energy that is required (or given out) to overcome the attraction of the nuclear charge and remove an electron from a gaseous atom. Removing 1 electron results in a +1 charge.
Main (or principal) energy levels, sub-levels and orbitals: The main energy levels, nare assigned whole number integers, n = 1, 2, 3, 4... . n = 1 represents the lowest energylevel. Each main energy level contains n sub-levels and a total of n^2 orbitals.
The magnitude of the ionisation energy will depend onthe charge on the nucleus.
The more electrons that have been removed from anatom, the greater the energy required to remove thenext electron. When the successive electrons are all inthe same energy level this is because of a reduction inthe amount of electron-electron repulsion and hencethe greater nuclear-electron attraction that results causesthe remaining electrons to move closer to the nucleus.

The number of protons in the nucleus influences the ionisation energy.

Sub-levels and orbitals are primarily determined by the number of neutrons in an atom.

The atomic mass of an atom affects its sub-levels and orbitals.

The main energy levels, sub-levels, and orbitals are determined by the whole number integer assigned to the main energy level, denoted by 'n'. Removing electrons and the Ionisation energy are key factors in understanding the structure of atoms.

Explanation

The main energy levels, sub-levels, and orbitals are determined by the whole number integer assigned to the main energy level, denoted by 'n'. Removing electrons and the Ionisation energy are key factors in understanding the structure of atoms.

2. Explain how successive ionization energy data is related to the electron configuration of an atom.

Successive ionization energies decrease as you move across a period due to a decrease in nuclear charge.

Sometimes with successive ionisation energies the nextelectron must be removed from a filled inner energy level,so that this electron will experience a much higher effectivenuclear charge and there is a sudden largerise in ionisation energy.
There is a steadyincrease in successive ionization energies for every element(decrease in e?-e? repulsion) and a steady increase goingacross the period (increase in nuclear charge).

Successive ionization energies remain constant regardless of changes in electron configuration.

Successive ionization energies increase as you move down a group due to a decrease in nuclear charge.

Successive ionization energies tend to increase due to factors such as higher effective nuclear charge and decreased electron-electron repulsion, resulting in a greater energy required to remove subsequent electrons.

Explanation

Successive ionization energies tend to increase due to factors such as higher effective nuclear charge and decreased electron-electron repulsion, resulting in a greater energy required to remove subsequent electrons.

3. State the relative energies of s, p, d and f orbitals in a single energy level.

P

State. s

D

F

In a single energy level, the relative energies of orbitals follow the order s

Explanation

In a single energy level, the relative energies of orbitals follow the order s

4. State the maximum number of orbitals in a given energy level.

Electrons in the same orbital must have the same spin.

Each orbital can have a maximum of 4 electrons.

Energy levels are not divided into orbitals.

Orbital: The cloud shapes that electron pairs travel around the nucleus in the quantum mechanicalmodel.
Each energy sub-level is divided into orbitalseach of which can contain up to two electrons, whichmust have opposite spins, as a consequence of the Pauliexclusion principle, which says that no two electrons in anatom can be in exactly the same state.
Each orbital can have a maximum of 2 electrons. n = 1 has one sub-level which iscalled an s sub-level and which contains one s orbital. n = 2 has two sub-levels: 2sand 2p; n = 3 has 3 sub-levels: 3s, 3p and 3d; n = 4 has 4 sub-levels:4s, 4p, 4d and 4f,etc.

In a given energy level, each sub-level is divided into orbitals, each of which can contain up to two electrons with opposite spins due to the Pauli exclusion principle.

Explanation

In a given energy level, each sub-level is divided into orbitals, each of which can contain up to two electrons with opposite spins due to the Pauli exclusion principle.

5. Draw the shape of an s orbital and the shapes of the px, py and pz orbitals.

Circular shape for s orbital and dumbbell shape for px, py, pz orbitals.

Rectangular shape for s orbital and spherical shape for px, py, pz orbitals.

Star shape for s orbital and cubic shape for px, py, pz orbitals.

See image.

The s orbital is spherical in shape while the px, py, and pz orbitals are dumbbell-shaped along the x, y, and z axes respectively.

Explanation

The s orbital is spherical in shape while the px, py, and pz orbitals are dumbbell-shaped along the x, y, and z axes respectively.