Atoms and Structure
What is meant by “atoms are electrically neutral”?
Equal numbers of protons and electrons cancel charge
What region contains most of an atom’s volume?
The electron cloud
What are energy levels in an atom?
Energy levels are fixed regions where electrons can exist in an atom
What do we call the pattern of light an element emits?
The pattern of light emitted is called a spectrum
A photon is a packet of light energy
What part of the atom has the most mass?
Most mass is in protons and neutrons in the nucleus (either protons/neutrons, or nucleus as answer)
Where are electrons located in an atom?
Electrons are located in the electron cloud around the nucleus
What happens when an electron gains energy?
When an electron gains energy, it jumps to a higher energy level (excited state)
What type of spectrum shows bright lines on a dark background?
A spectrum with bright lines on a dark background is an emission spectrum
What type of energy do photons carry?
Photons carry electromagnetic energy
How does atomic number define an element’s identity?
Atomic number = number of protons, defines element
Why can electrons only absorb specific photon energies?
Only photons with exact energy gaps can be absorbed
What happens when an electron falls to a lower energy level?
When an electron falls to a lower level, it releases energy as a photon (light)
Why does each element have a unique emission spectrum?
Each element has a unique spectrum because it has unique electron energy levels
What happens when a photon is absorbed by an atom?
When a photon is absorbed, an electron moves to a higher energy level
Explain why protons determine chemical identity but neutrons do not
Protons define element identity; neutrons change isotope only
Why do electron transitions produce different types of emitted light (high energy vs low energy photons)?
Different transitions involve different energy gaps between levels, and larger gaps produce higher-energy (higher frequency, shorter wavelength) photons while smaller gaps produce lower-energy (lower frequency, longer wavelength) photons.
What process releases a proton from an electron? How about when it takes in a proton?
Emission, absorption (respectively)
What is the difference between emission and absorption spectra?
Emission spectra are light emitted when electrons drop energy levels, while absorption spectra are dark lines where light is absorbed
How is photon energy related to wavelength?
Photon energy is inversely proportional to wavelength (higher energy = shorter wavelength)
Compare how changing protons vs neutrons affects an atom
Protons change element; neutrons change mass/isotope
Explain why electron transitions between energy levels can be thought of as having “different sizes of jumps,” and how this relates to the type of photon produced.
Electron energy levels are quantized, so electrons can only move between fixed levels. Each possible transition corresponds to a specific energy difference. A larger jump releases more energy as a higher-frequency, shorter-wavelength photon, while a smaller jump releases less energy as a lower-frequency, longer-wavelength photon. This is why spectra show discrete lines instead of a continuous range.
Explain why energy levels are quantized.
Energy levels are quantized because electrons can only exist in discrete allowed energies, not continuous values
How can spectra be used to identify elements in stars?
Spectra identify elements in stars by matching observed spectral lines to known elements, visible in the bright and dark bands shown
Why do different elements emit different wavelengths of light?
Different elements emit different wavelengths because they have different spacings between electron energy levels. One element can have different eV between each energy level compared to others.