A New Atomic Model

1. A New Atomic Model Chapter 4 Section 1

2. Problems with Rutherford’s Model • Did not explain where the __________ were specifically arranged • Did not explain why the ___________ charged ________ did not get drawn into the positively charged __________ • How could the positively charged protons be ___________________in the nucleus?

3. The Wave Description of Light • _________________________: a form of energy that exhibits wavelike behavior as it travels through space • __________is a form of electromagnetic radiation • ______________________: all the forms of ________________________

4. More Facts about Light • Light travels at ______________ through a vacuum • ____________: (λ) is the _______ between corresponding points on adjacent waves • Units like _________ or ______________ etc. • _________: (ν) is the number of waves that pass a given point in a specific time • Measured in waves/s (cycles / sec or just sec-1)which is called a __________(Hz)

5. Wave (a) has a ___________ wavelength and a _________frequency than wave (b). They are ____________related.

6. The Photoelectric Effect • ____________________: the emission of electrons from a metal when light shines on the metal • The ___________ of the light striking the metal must have a certain ___________ __________or no electrons were emitted, even if the light was very bright or shown on it for a long time.

7. More about Light • The wave theory of light predicted that light of _______________would supply enough energy to eject an __________ from the metal • _________, a German physicist, proposed that light must travel in _____________(packets; photons) of energy • Albert Einstein expanded on this theory by introducing the ____________________theory

8. The Wave- Particle Description of Light • ________: the minimum quantity of ______ that can be lost or gained by an atom • __________: a particle of ____________ radiation having zero ______and carrying a quantum of __________ • The energy of a particular photon depends on the _________of the radiation. They are __________related.

10. Visual of Photoelectric Effect • Electrons in different metals require _________________________________ to exhibit the photoelectric effect.

11. Ground State vs. Excited State • ___________: the lowest energy state of an atom • ________: a state in which the atom has a _________ potential energy than it has in the ground state • Excited atoms will return to the _______ ________upon losing the proper amount of ____________.

12. Radiant Energy Spectrum • The complete radiant energy spectrum is an uninterrupted band, or _____________________. • The radiant energy spectrum includes most types of radiation, most of which are invisible to the human eye.

13. Visible Spectrum • _____________ usually refers to radiant energy that is visible to the human eye. • The _________________________is the range of wavelengths between 400 and 700 nm. • Radiant energy that has a wavelength lower than 400 nm and greater than 700 nm cannot be seen by the human eye.

14. Emission-Line Spectrum • When an atom returns to its ground state, it emits _________________ • __________________: a diagram or graph that indicates the degree to which a substance emits radiant energy with respect to wavelength; shows the type of ________________(“color”).

15. Hydrogen Atom Emission-Line Spectrum • An _______current is passed through __ at low pressure • There was a _________ light emitted • When the light was passed through a prism, it was separated into ________ colors of ___________. • This was the _____________________.

16. Emission Line Spectra • When an electrical voltage is passed across a gas in a sealed tube, a series of narrow lines is seen. • These lines are the _________________________. The emission line spectrum for hydrogen gas shows three lines: 434 nm, 486 nm, and 656 nm.

17. More about Hydrogen • There were other series of lines in the UV and IR regions of hydrogen’s emission-line spectrum • The series are called Lyman (UV), Balmer(visible), and Paschen (IR) after their discoverers

18. The Bohr Model • _____________was a Danish physicist. • He linked the atom’s electron _______to ___________________. • According to his model, the electrons can circle the nucleus only in __________ allowed paths, or _________. • The electron is in its ___________energy state (ground state) when it is closest to the _______________.

19. Electrons Around the Nucleus • The orbit is separated from the nucleus by an _________space where the electron __________exist. • When the atom is in the _________state, the electron is in a ________orbit farther from the nucleus. • There are only ________orbits available, like the rungs of a ladder.

20. Evidence for Energy Levels • Bohr realized that this was the evidence he needed to prove his theory. • The electric charge temporarily excites an electron to a higher orbit. When the electron drops back down, a photon is given off. • The red line is the least energetic and corresponds to an electron dropping from energy level 3 to energy level 2.

21. Energy must be added to the atom to move an electron to a higher level. This is called ____________. • When a hydrogen atom is in an _______ state, the electron is in a ________orbit. • When the atom returns to the ground state, it emits energy in the form of a photon. This is called ______________.

22. More about Bohr’s Model • Bohr related the possible energy-level changes to the lines in the hydrogen emission-line spectrum • He calculated mathematically values for the lines • Unfortunately, Bohr’s model did not explain the emission-line spectrum of atoms with _______________________.

23. Emission-Line Spectra • The emission spectrum of each element is ____________. • Emission spectra can be used to ______ __________________. • Also used to determine the relative composition of stars

24. “Fingerprints”- Emission-Line Spectra