# Chapter 5 Chemistry

Chapter 5: Electron Clouds and Probability

## Terms

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- If all points of = probability are connected,
- some 3-D shape is formed.
- As the wavelength of an object increases,
- its momentum decreases.
- Light
- has the properties of both waves and particles
- in the 3rd and 4th levels
- there is overlapping
- in an atom there are many points of
- equal probability
- f
- 7 pairs electrons & 7 orbitals
- The 3rd quantum # is m -
- represents orbitals and indicates their direction in space
- orbital
- The space that can be occupied by one pair of electrons
- vectors have both
- magnitude and direction
- The more certain we are of the momentum
- the less certain we are of position and vice versa.
- DeBroglie thought
- if Planck were correct then it might be possible for particles to have some of the properties of waves
- wave-particle duality of nature
- The two-sided nature of waves and particles
- Each electron in an atom can be described
- as a unique set of four quantum numbers: n, l, m, s
- Max Planck
- theorized that energy is made up of discrete amounts of energy called quanta. This theory seemed to give waves properties of particles
- An electron effectively occupies
- all the space around a nucleus.
- d
- 5 pairs electrons & 5 orbitals
- sublevel names:
- (lowest energy to highest) s, p, d, f
- Momentum
- is a vector quantity which consists of mass times velocity
- Quantum mechanics describes
- the behavior of extremely small particles traveling at velocities near that of light
- The # of sublevels in an energy level =
- the value of n, the principal quantum #.
- Heisenberg's Uncertainty Principle
- the exact position and momentum of an electron cannot be determined at the same time.
- DeBroglie's equation
- ʎ=h/mv
- s
- 1 pair electrons & 1 orbital
- An energy level is actually made up of
- many energy states closely grouped together ( called sublevels )
- p
- 3 pairs electrons & 3 orbitals
- The symbol --> above a quantity
- means it is a vector quantity
- An electron can only occupy specific energy levels when:
- 1. The energy levels are numbered with positive integers starting with 1, 2. The principal quantum number, n, describes the energy level, 3. The maximum # of electrons in an energy level = 2n^2
- Newtonian or classical mechanics describes
- the behavior of visible objects traveling at normal velocities
- Momentum equation
- p = mv
- Particles (matter) also have both properties
- In large particles we can ignore wave characteristics. In small particles (like electrons) we cannot.
- since p = mv
- then ʎ= h/p
- probability =
- # of times in position X/ divided by sum of times in all positions
- The position of an electron can best be represented by
- a cloud
- We cannot observe
- both the wave characteristics and particles characteristics of an electron at the same time.
- The second quantum number, l
- describes sublevels