Question 1

Which property of helium makes it suitable for use in modern blimps instead of hydrogen?

Accepted Answer

Helium is an inert gas with a stable electron configuration.

Question 2

What is the relationship between wavelength ($$\lambda) $$and frequency ($$
u) of $$electromagnetic radiation?

Accepted Answer

They are inversely proportional: $$\lambda \propto \frac{1}{
u}$$

Question 3

Arrange the following types of electromagnetic radiation in order of increasing energy per photon: microwaves, visible light, X-rays.

Accepted Answer

Microwaves \u003c Visible light \u003c X-rays

Question 4

Which statement best explains why the emission spectrum of hydrogen contains only specific wavelengths?

Accepted Answer

Energy levels in hydrogen are quantized, so electrons transition between fixed orbits.

Question 5

According to the quantum-mechanical model, what does an orbital represent?

Accepted Answer

A probability map showing where an electron is likely to be found.

Question 6

Which principle states that no more than two electrons can occupy the same orbital, and they must have opposite spins?

Accepted Answer

Pauli exclusion principle

Question 7

A neutral atom of sodium (Na) has the electron configuration $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^1. $$How many valence electrons does sodium have?

Accepted Answer

1

Question 8

Which element is most likely to form a $$2^+$$ ion in chemical reactions?

Accepted Answer

Magnesium (Mg)

Question 9

What is the electron configuration for phosphorus (P), atomic number 15, using noble gas core notation?

Accepted Answer

$$[Ne] 3s^2$ 3p^3$

Question 10

Which periodic trend describes the change in atomic size as you move down a column in the periodic table?

Accepted Answer

Atomic size increases due to higher principal quantum number ($$n).$$

Question 11

Why are noble gases chemically inert?

Accepted Answer

They have a full set of valence electrons, resulting in a stable, low-energy configuration.

Question 12

Which block of the periodic table contains the transition metals?

Accepted Answer

d block

Question 13

Which of the following statements about ionization energy is correct?

Accepted Answer

Ionization energy increases as you move to the right across a period.

Question 14

A red shirt appears red because:

Accepted Answer

It reflects red light and absorbs all other colors.

Question 15

Which type of electromagnetic radiation has the shortest wavelength and highest energy per photon?

Accepted Answer

Gamma rays

Question 16

Which rule explains why electrons occupy orbitals of equal energy singly before pairing?

Accepted Answer

Hund's rule

Question 17

Which of the following elements has the greatest metallic character?

Accepted Answer

Sodium (Na)

Question 18

What is the effect of increasing the number of protons in the nucleus as you move across a period?

Accepted Answer

It decreases atomic size due to greater nuclear pull on electrons.

Question 19

Which of the following best describes the difference between the Bohr model and the quantum-mechanical model of the atom?

Accepted Answer

The Bohr model uses fixed orbits, while the quantum-mechanical model uses probability maps (orbitals).

Question 20

Which electron configuration represents a completely filled principal shell?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$

Electrons in Atoms and the Periodic Table: Chapter 9 Study Notes

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