Electrons Electrons are found circling the nucleus at extremely fast speeds. + and – attract. The reason e- are not pulled into the nucleus is because of how fast they are moving. (Kinetic Energy)

Energy E- near the nucleus require lower energy E- away from the nucleus require higher energy E- can jump from one level to another by gaining or losing energy Because of this, an e- is most likely to be found in the 1 st energy level, closest to the nucleus. (ground state) Aufbau Principle Energy Level Max. # of e- Energy 12Lowest Higher

Electron Energy Levels There is a maximum # of e- each level can hold. The first energy level can hold only 2 e- (H and He) The second can hold 8 more (Li-Ne) The third can hold 18, but 8 will fill up first (Na-Ar) Nameelectrons1 st 2 nd 3 rd Be422 Na11281 N Ar

Valence Electrons The e- in the outer most energy level are called valence electrons. The number of valence e- determines how an element bonds. We can easily find out how many valence electrons elements in columns 1, 2, and have. Transition metals (middle of PT) usually have 1 or 2 valence e-. (We cannot predict)

Valence Electrons Skip 3-12

Valence cont. How many valence electrons do the following elements have? Ca _______Si _________ Li ________Cl _________ P ________F __________ Ar _______B __________

Answers Ca= 2 Si = 4 Li = 1 Cl = 7 P = 5 F = 7 Ar = 8 B = 3

Sublevels Within the energy levels, electrons occupy specific sublevels. S- group 1, 2 (2 e-) P- group (6 e-) D- group 3-12 (transition metals) (10 e-) F- Lanthanide, Actinide (14 e-)

Energy The energy levels don’t fill up perfectly in order. E- fill up in order of energy. The 4s sublevel requires less energy than the 3d sublevel, so e- fill it first. The correct order follows the Periodic Table.

Electron Configuration on the Periodic Table S Block P Block D Block F Block

What the PT really looks like 6s 4f 5d

Electron Configuration Write the electron configuration of the following elements: Aluminum ___________________ Chlorine _____________________

Answers Aluminum: 1s 2 2s 2 2p 6 3s 2 3p 1 Chlorine: 1s 2 2s 2 2p 6 3s 2 3p 5

Noble Gas Configuration Put the previous noble gas in ( ) and start from there. Aluminum –Noble gas [Ne]3s 2 3p 1 Chlorine –Noble gas [Ne] 3s 2 3p 5

Electron Configuration-3 rules Aufbau Principle: e- occupy orbitals of lowest energy first. Pauli Exclusion Principle: To occupy the same orbital e- must have opposite spin Hund’s Rule: e- don’t double up in an orbital until they have to. Carbon: 1s 2s 2p

Find the e- config for Fe Fe= ____________________________ 1s 2s 2p 3s 3p 4s 3d

Electromagnetic spectrum The quantum mechanical model grew out of the study of light. Around 1900 light was believed to consist as a wave. Electromagnetic spectrum: Radiation over a broad range of wavelengths. (radio waves longest, gamma rays shortest) Visible light was in the middle

c = f x λ c = speed of light (3.0 x 10 8 m/sec) f = frequency of wave (waves per sec) in Hz λ= wavelength in meters If the wavelength increases, what should happen to the frequency?

Atomic Emission Spectrum When electric current is passed through a gas, the e- are energized. When atoms absorb energy, their e- move to higher energy levels. These e- lose energy by emitting light when they return to lower energy levels. Each element emits a different of spectra of light-like an element fingerprint.

Photoelectric effect e- are ejected when light shines on metal…but not every frequency of light works E=hv

Einstein Einstein determined light can also be described as a quanta of energy that behave as if they were particles. (photon) Light behaves as both a wave and a particle.

Heisenberg Uncertainty Principle It is impossible to know both the position and velocity of a tiny particle at the same time. Once you use lab methods to find position, you alter its motion The act of measuring the position of an e- changes its velocity

Electron Dot Diagrams Write the element symbol Use dots to represent the # of valence e- Make a square with up to 2 dots on each side, up to a total of 8.