Exploring Atomic Emission Spectra

Which of the following best describes the quantum mechanical model of the atom?

• Electrons orbit the nucleus in fixed paths.

• Electrons exist in probability clouds called orbitals.

• Electrons are embedded in a positively charged sphere.

• Electrons are stationary around the nucleus.

Answer explanation

The quantum mechanical model describes electrons as existing in probability clouds called orbitals, rather than in fixed paths or as stationary particles. This reflects the uncertainty and wave-like nature of electrons.

Tags

DOK Level 2: Skill/Concept

Answer explanation

To find the energy of a photon, use the formula E = h * f. Substituting h = 6.626 x 10^-34 Js and f = 5 x 10^14 Hz gives E = 3.313 x 10^-19 J, which matches the correct answer.

Tags

DOK Level 2: Skill/Concept

What is the relationship between wavelength and frequency in the electromagnetic spectrum?

• They are directly proportional.

• They are inversely proportional.

• They are unrelated.

• They are equal.

Answer explanation

Wavelength and frequency are inversely proportional, meaning as one increases, the other decreases. This relationship is described by the equation: speed = wavelength × frequency, where speed is constant in a vacuum.

Tags

DOK Level 2: Skill/Concept

Answer explanation

To find the wavelength, use the formula \( \lambda = \frac{c}{f} \). Here, \( c = 3 \times 10^8 \, \text{m/s} \) and \( f = 6 \times 10^{14} \, \text{Hz} \). Thus, \( \lambda = \frac{3 \times 10^8}{6 \times 10^{14}} = 5 \times 10^{-7} \, \text{m} \), which is the correct answer.

Tags

DOK Level 2: Skill/Concept

Which of the following statements is true about atomic emission spectra?

• They are continuous spectra.

• They consist of discrete lines.

• They are identical for all elements.

• They are only visible in the ultraviolet range.

Answer explanation

Atomic emission spectra consist of discrete lines, which represent specific wavelengths emitted by electrons transitioning between energy levels. This is unique to each element, unlike continuous spectra.

Tags

DOK Level 2: Skill/Concept

How does the quantum mechanical model explain the stability of atoms?

• Electrons are fixed in place, preventing collapse.

• Electrons are in constant motion, creating stability.

• Electrons exist in quantized energy levels, preventing collapse.

• Electrons are repelled by the nucleus, maintaining distance.

Answer explanation

The quantum mechanical model explains that electrons exist in quantized energy levels, which prevents them from spiraling into the nucleus. This quantization leads to stable atomic structures.

Tags

DOK Level 2: Skill/Concept

Answer explanation

To find the frequency (f), use the formula f = c / λ. Here, c = 3 × 10^8 m/s and λ = 4 × 10^{-7} m. Thus, f = (3 × 10^8) / (4 × 10^{-7}) = 7.5 × 10^{14} Hz, which is the correct answer.

Tags

DOK Level 2: Skill/Concept

Answer explanation

To find the energy of a photon, use the formula E = hc/λ. Substituting h = 6.626 x 10^-34 Js, c = 3 x 10^8 m/s, and λ = 3 x 10^-7 m gives E ≈ 9.939 x 10^-19 J, which matches the correct answer.

Tags

DOK Level 2: Skill/Concept

Which of the following is a key application of the quantum mechanical model?

• Predicting planetary motion.

• Explaining chemical bonding.

• Describing gravitational forces.

• Calculating kinetic energy.

Answer explanation

The quantum mechanical model is essential for explaining chemical bonding, as it describes how electrons behave in atoms and molecules, influencing their interactions and bond formation.

Tags

DOK Level 2: Skill/Concept

Answer explanation

To find the frequency of a photon, use the formula E = hf, where E is energy and h is Planck's constant. Rearranging gives f = E/h. Substituting E = 4 x 10^{-19} J and h = 6.626 x 10^{-34} Js yields f = 6.04 x 10^{14} Hz.

Tags

DOK Level 2: Skill/Concept