What does the location of electrons in the electron cloud help us do?
Predict reactivity
Electromagnetic Radiation
-form of energy
-travels in waves
Speed of Light
-3.00 x 10^10 cm/s OR 3.00 x 10^8 m/s
-C=λν
Wavelength
-λ (lambda)
-distance between corresponding points on adjacent waves
Frequency
-ν (nu)
- # of waves that pass a given point in a specific amt. of time, usually one second
-SI unit for frequency is a Hertz
Hertz
1 Hertz = 1 wave/sec = 1/sec
Continuous Spectrum
a spectrum in which all wavelengths within a given range are included
Wave/energy theory of Light
-moved w/ wavelength + frequency
- has no standing mass
- de-localized (everywhere - no definite spot)
- Young double-split experiment
Particle/matter
-exists in tiny bundles (photons)
-photons possess energy
-photoelectric effect
Photoelectric effect
-emission of electons by certain metals when light shines on them
- dependent on frequency of light
-particle/matter theory
electromagnetic spectrum
consists of all electromagnetic radiation, arranged according to increasing wavelengths
Max Planck
when hot objects lose heat it is not continuous - it is lost in small specific amts. called QUANTA
Quantum
a finite quantity of energy that can be gained/lost by an atom
Photon
-a particle of electromagnetic radiation carrying a quantum of energy
-smallest piece of energy
E = hν
E - energy of a photon
h - Planck’s constant
ν - frequency of radiation (1/s)
Energy level
ex : n=3
Energy level orbital
ex: 3s ; 3p ; 3d
What was the Neil Bohr Model based on?
Solar System
Niel Bohr Model
1) electrons orbit the nucleus in set paths (orbit is a 2D path)
2) total energy of an electron increases as it moves farther from the nucleus
*Only worked for H atom
Bohr’s approach did not explain
1) spectators of atoms w/ more than 1 electron
2) chemical behaviors of an atom
Visible Light
emitted when an electron passes from a state of higher energy to a state of lower energy
Ground State
state of lowest energy of an atom
Excited State
state in which an atom has a higher potential energy than it has in its ground state
Visible Light Is Produced when:
1) atom is at ground state
2) energy is added to atom + electrons absorb energy
3) electrons gain energy + jump to higher energy levels (excited state)
4) electrons do not have enough energy to stay in excited state they fall back down to ground state
5) any extra energy electrons have is emitted … thus a quantum of energy (light) is given off
