CH 04

What identifies whether an atom carries a charge as an ion or is neutral?

The number of electrons.

What identifies the type of element?

The number of protons.

What is expected in a spectrum of a star observed from above Earth's atmosphere compared to ground-based observation?

It would show slightly fewer absorption lines.

What type of spectrum would sunlight reflected from Saturn's moon Titan be expected to be?

Absorption spectrum.

If the temperature of neon gas is increased, what happens to the emission spectrum?

We would observe fewer red lines and more blue lines.

What can be inferred about a star with many red and blue absorption lines compared to one with many blue absorption lines?

It is cooler than the other star.

What are the basic components of a simple spectroscope?

A slit, a mirror, a detector, a prism, and an eyepiece or screen.

What additional components are used in spectrographs for modern astronomical observations?

A telescope, a dispersing device, and a detector.

What defines an atom that has been ionized?

It has different numbers of protons and electrons.

How many different photons can be emitted as a hydrogen atom in the third excited state falls to the ground state?

Up to 4 different photons.

Compared to a transition from the first excited state to the ground state, what is the energy of a photon emitted from the third excited state to the second excited state?

Lower energy.

Compared to complex atoms like neon, how many excited states does simple hydrogen have?

Fewer excited states.

What can astronomers determine from analyzing starlight?

The star's motion, composition, and temperature.

What is the characteristic of absorption lines in the hottest stars?

They are thin and distinct.

What is the characteristic of absorption lines in the fastest spinning stars compared to slowly rotating stars?

They are broad and fuzzy.

What happens if most electrons of a star's abundant element are not in a condition to absorb light?

The element may not produce strong lines.

What determines the properties of a star observed from its spectrum?

Composition, temperature, and motion.

What happens to a star's hydrogen lines if it is very hot?

The lines of hydrogen are weak due to ionization.

What does the temperature of a star help determine about its appearance?

The color of the star's glow (hotter stars appear bluer, cooler stars appear redder).