Electronic Structure and Periodic Properties of Elements

Gen Chem 1: Lecture 3

What does the Bohr model explain?

The emission spectrum of the hydrogen atom but not always the spectra of other elements.

What is the relationship between wavelength and frequency for electromagnetic waves?

The product of wavelength and frequency equals the speed of the wave (n * λ = c).

What is the principle behind the Uncertainty Principle proposed by Heisenberg?

The product of the uncertainties in both the position and speed of a particle is inversely proportional to its mass.

What does effective nuclear charge (Z_eff) measure?

The net attraction an electron feels from the nucleus, taking into account shielding from other electrons.

What is the Pauli Exclusion Principle?

No two electrons in the same atom can have the same set of quantum numbers; only two electrons can occupy the same orbital if their spins are opposite.

What do electrons in the outermost shell of an atom represent?

They are called valence electrons and are involved in chemical bonding.

What is the significance of the principal quantum number (n)?

It indicates the main energy level or shell of an electron in an atom.

What do the four quantum numbers describe?

They describe the state of an electron in an atom, including its energy level, shape, orientation, and spin.

What characterizes a cation?

A cation is formed when an atom loses one or more electrons, resulting in a positive charge.

What happens during the photoelectric effect?

Electrons are ejected from a metal surface when struck by light above a certain threshold frequency.

What is the arrangement of elements in the periodic table based on?

The periodic law states that properties of elements are periodic functions of their atomic numbers.

How is the energy of atomic orbitals affected by the principal quantum number (n)?

Energy increases as the principal quantum number increases, with sub-shells increasing in energy order as s < p < d < f.

What is the difference between ionic and molecular compounds?

Ionic compounds are formed by the transfer of electrons from metals to nonmetals, while molecular (covalent) compounds are formed by sharing electrons.

What does the term 'wave-particle duality' refer to?

The concept that light exhibits both wave-like and particle-like properties.

What is the role of the effective nuclear charge in atomic size?

As Zeff increases across a period, the atomic size decreases due to the greater attractive force on electrons.