Astronomy Physics & Chemistry Flashcards
3 forms of energy
- Kinetic (motion)
- Radiative (light)
- Potential (stored energy which may be converted)
Mass-energy?
Embodies idea that mass itself is form of energy, which Einstein discovered with E = mc^2
Thermal energy?
Represents collective kinetic energy of many individual atoms or molecules moving randomly within substance like rock or the air. Higher temperature = more rapid motion = more thermal energy.
Law of conservation of energy?
Energy can change from one form to another but it can’t be created or destroyed.
Electromagnetic waves?
Light which is characterized by rapidly changing electric & magnetic fields.
Light is characterized by?
Wavelength, the distance between adjacent peaks
Frequency, rate at which electric & magnetic fields change.
Unit of frequency = Hertz = waves or cycles per second.
Photons
The distinct pieces in which light comes with.
What is the speed of light?
Wavelength of photon x frequency of photon.
Longer wavelength = lower frequency
Shorter wavelength = higher frequency.
Electromagnetic spectrum?
Complete range of possibilities of light.
Visible light?
Lilght that we can see, which is tiny portion. Goes from 400nm to 700nm (one nanometer is a billionth of a meter).
Infrared?
Light with wavelengths longer than those of red light.
Radio waves are longest-wavelength light.
Region near border between infrared & radiowaves?
Microwaves.
Ultraviolet?
Light with wavelengths shorter than blue light. Shortest wavelength is gamma rays.
Region between ultraviolet and gamma rays?
X-rays.
Spectroscopy?
Collecting light through telescope then dispersing it into a spectrum in much the same way a prism disperses light into rainbow of color.
3 basic types of spectra that we observe?
- Continuous spectrum - smooth light across broad range of wavelengths
- Emission line spectrum - bright lines on dark background
- Absorption line spectrum - dark lines on continuous background.
Thermal radiation?
Dense objects which emits light with a continuous spectrum, which allows us to determine the object’s surface temperature.
What can spectral lines tell us?
Each chemical element, ion and molecule produces its own unique pattern of spectral lines - this pattern helps us to identify what produced it and can allow us to determine the chemical composition of distant objects. Sometimes we can even determine isotopes.
What are atoms build of?
Protons, neutrons & electrons.
Where are protons & neutrons found?
Tiny nucleus at center of atom. Rest of atom’s volume contains electrons which surrounds nucleus. Most of atom’s mass resides in its nucleus because protons and neutrons are each about 2000 times as massive as an electron.
What do properties of atom mainly depend on?
Electrical charge in its nucleus.
How do charges of protons and electrons and neutrons work?
We define the proton as basic unit of positive charge. An eelctron has a negative charge. Neutrons are neutral.
An atom is held together by attraction between positively charged protons in nucleus and negatively charged electrons that surround the nucleus.
Ions?
Atoms that lose or gain electrons, which means they have a net electrical charge. Positive ion: atom that has lost one or more electrons, so it has an overall positive charge. Negative ion: atom that has gained one or more electron, giving it a net negative charge.
Relationship between charged particles?
Opposite charged attract one another, similarly charged repel.
Most of atoms contain same number of electrons as protons, making them electrically neutral.
Interactions between atoms are almost exclusively interactions between electrons (as nucleus is deeply buried).
