People's Education Press High School Chemistry: Elective Compulsory Course Part Two: Observing the Atomic Microscopic World Through Spectra

Welcome to this millennium-spanning journey into the microscopic world. Our story begins in ancient Greece, where philosopher Democritus proposed the concept of“atom (ATOM)”meaning "indivisible." Throughout the long history of science, humanity's quest for the essence of matter has never ceased. From Dalton's solid sphere model to modern quantum mechanics, we have finally found a messenger capable of bridging the microscopic gap and allowing atoms to 'speak'—spectra.

The Atom's 'Digital Fingerprint'

As shown in [Figure 1-26], Ramsay (William Ramsay) revealed the mysteries of the microscopic world through spectral analysis of noble gases. Spectra are not continuous rainbows but discrete lines. Thisdiscretenessconveys a profound conclusion: atomic internal energy is discontinuous, i.e.,quantized. Each spectral line corresponds to an 'elegant transition' of electrons between different energy levels.

Energy Levels and Sublevels: The Staircase of the Microscopic Theater

Energy Shells (Shells): Ordered from lowest to highest energy as K, L, M, N, O, P, Q. This determines how far electrons are from the nucleus.
Subshells (Subshells): Divided within the same energy shell into different orbital types such as s, p, d, f. The s orbital resembles a sphere, while the p orbital looks like a pair of dumbbells.
Aufbau Principle: Electrons always occupy the lowest-energy orbitals first. It is precisely these arrangement rules that build the vast and varied world of chemistry.

Historical Fact: The Discovery of Helium

In 1868, helium was first discovered in the solar spectrum by humans, predating its discovery in laboratory settings on Earth. This proves that spectral analysis can not only identify known substances but also explore the unknown. Spectra are humanity's 'eyes' for probing the microscopic world.

QUESTION 1

The electron configuration of Zn outside the nucleus is __________________.

[Ar]3d¹⁰ 4s²

[Ar]4s² 4p⁶

[Ar]3d¹⁰ 4s¹

1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁸ 4s² 4p²

QUESTION 2

Using S and P as examples, how can you determine the valence electron count based on a main-group element’s position in the periodic table?

The number of valence electrons equals its period number

The number of valence electrons equals its group number

The number of valence electrons equals half its nuclear charge

QUESTION 3

Why does the ground-state nitrogen atom's orbital diagram show three unpaired electrons with parallel spins in the 2p orbital, rather than one pair and one single electron?

Following the energy minimum principle

Following the Pauli exclusion principle

Following Hund's rule

QUESTION 4

Which of the following curves correctly shows the trend of melting points of halogen elements' pure substances changing with increasing nuclear charge?

Increases with increasing nuclear charge

Decreases with increasing nuclear charge

Shows periodic fluctuations

QUESTION 5

Why is the ground-state electron configuration of helium 1s² instead of 1s¹ 2s¹?

The energy of the 1s orbital is lower than that of the 2s orbital

The Pauli principle limits the filling of the 2s orbital

An s orbital can hold only one electron