Chapter 5: The sun, atoms, spectra

What can excite atoms?

light/photons

For an electron to jump from an inner to an outer orbit, what must the electron do?

the electron must absorb a specific amount of energy

What must an electron do to jump from an outer orbit to an inner orbit?

the electron must emit a specific amount of energy

______________ in atoms have distinct energy levels

electrons

What type of spectrum does neon light produce?

emission

How does light tell us the temperatures of stars?

thermal radiation spectrum

What do astronomers learn from spectra?

-Temperature of a hot body (continuous spectrum) -elemental and molecular composition of stars/hot clouds or absorbing gas/dust clouds (emission and absorption spectrum) -relative velocity of approach or recession (Doppler shift)

Why is the sky red?

-The setting Sun passes through a thicker amount of atmosphere. -More blue light is scattered to space.

How do we know what happens under the surface of the sun/inside the sun?

-mathematical models that use law of physics -by measuring doppler shifts

What are the 3 types of spectra?

1. Continuous 2. Emission 3. Absorption

What is the temperature of the suns core?

15 million K

What is the composition of the sun?

3/4 (70%) of Hydrogen, 1/4 (28ish%) helium, and 2% of other elements. SO almost entirely hydrogen and helium (98%)

What is the surface temperature of the sun?

6000K

What are the major layers of the Sun, from inside out?

Core, radiation zone, convection zone, photosphere, chromosphere, and corona

Can a photon with too much or too little energy be absorbed by electrons?

No. Will not drive electron to exact energy level

What phase of matter is the sun in?

Plasma

_______________ is the process of dispersing light into its spectrum (different wavelengths). It allows astronomers to determine chemical composition of stars.

Spectroscopy

The ___________ ___________ law shows the relationship between energy radiated by the body and the temperature. Higher the temperature, higher the total amount of energy radiated.

Stefan Boltzman law

_________ (absorption) lines in the sun's spectrum are caused by atoms in the sun's (or Earth's) atmosphere between you and the sun's photosphere

dark

Why does fusion occur at the suns core?

The core temperature and pressure are so high that colliding nuclei can come close enough together for the strong force to overcome electromagnetic repulsion and bind them together. Forces shit the repels to bind together.

Why don't we glow in the dark?

We only emit light that is visible to our eyes. Infrared.

Does each chemical element, ion, molecule have unique set of energy levels?

YES

We know the composition of the sun by identifying the ______________ lines in the Sun's spectrum. This is also why we know chemical composition of other stars as well.

absorption

The radiation emitted by an opaque (non transparent) object is called _____________ radiation/ Its continuous thermal radiation spectrum depends on only one property: its temperature

blackbody

What colour is the hottest star?

blue

white light means that all colours are ___________, while black light means ____ _________.

combined no light

the __________ state of an atom is when one of its electrons is in a higher energy orbital than the ground state. Atoms can become ___________ by absorbing a photon of a specific energy, or by colliding with a nearby atom. Happens by simply illuminating the atoms by giving them photons/energy.

excited

The sun is a cloud of ___________ that used to be cold, then gravity heated it up until the heat was high enough for fusion reactions.

gas

Bright blobs on photosphere are where hot gas is reaching surfaceThe visual pattern is called _________________. It lasts for only 10 to 20 minutes before fading away. Faded granules are continuously replaced by new ones

granulation

____________ _____________ causes the suns size to remain stable. It is the outward pressure of hot gas balances the inward force of gravity at every point within the Sun

gravitational equilibrium

_________ state is the lowest energy state that an electron can have within an atom.

ground

At the centre of the sun, what does fusion turn hydrogen into?

helium, energy, neutrinos

___________ is a state of an atom that has had at least one of its electrons removed.

ionized

By gaining or loosing the correct amount of energy, what can an electron do? What is this called?

jump from one orbit to another. This is called quantum jump.

How does the Sun generate energy today?

nuclear fusion

What process creates energy in the sun?

nuclear fusion of hydrogen into helium in the suns core generates the suns energy.

the ______________ is the visible surface of the sun

photosphere

The number of ____________ in the nucleus decides what kind of atom and element it is. Each is unique.

protons

If you put two protons near each other, due to electromagnetic force the two protons will _________ each other.

repel

Why is the sky blue?

small particles scatter blue light more effectively, and since air molecules are smaller than visible light, they scatter blue light.

Every element can be fingerprinted by its ______________.

spectra

Each type of atom, ion, and molecule has a unique ___________ fingerprint of absorption or emission lines. Observing the fingerprints in a spectrum tells us which kinds of atoms are present.

spectral

We can identify the chemicals in gas by their fingerprints in the _____________ and with additional physics, we can figure out abundances of the chemicals, and much more.

spectrum