Daily Science (pg. 33 or 34) Write the short hand notation for Iron- 56. What does the number 56 tell you? Write a nuclear reaction for the alpha decay of Amercium-244. Write a nuclear reaction for the beta decay of Einsteinium-254. If Plutonium-244 decays to form Amercium-244, what type of radioactive particle was emitted? If the half-life of Uranium is 1.2 hours, how much of a 94 g sample will have decayed after 7.2 hours? Carbon’s half- life is 5.6 years. If after 16.8 years you are left with a sample of 2.3 g, how much was originally there?

Electrons Pg. 37

Electrons as a wave Scientists say an electron acts as a wave and as a particle. A wave has a frequency, wavelength, and amplitude. Lower frequency= longer wavelength (less energy) The electromagnetic spectrum contains all frequencies of electromagnetic radiation.

Electrons as a particle Wave model doesn’t explain the different wavelengths of light at different temperatures. Max Planck discovered that that matter can gain or lose energy only in small specific amounts called quanta. Quantum- the minimum amount of energy that can be gained or lost by an atom.

Equations about electrons de Broglie equation– predicts that all moving particles have wave characteristics Heisenberg uncertainty principle- cant know both the velocity and position of an electron at the same time Schrodinger wave equation-treated the electron in a hydrogen atom as a wave

Electron Orbitals Even though an electrons exact location can not be determined, we can make a good guess. Electrons exist in orbitals that correspond with energy levels. Electrons that exist in the last energy level are called valence electrons

Types of orbitals There are four types of orbitals: s, p, d, and f

The s orbital Simplest orbital Spherical Can hold 2 electrons

The p orbital Shaped like a dumbbell Has 3 orientations Can hold 6 electrons

The d and f orbitals More complex d can hold 10 electrons f can hold 14 electrons

Orbitals and energy levels Each energy level can only hold a specific amount of electrons as determined by the orbital type Energy Level Orbital found in energy level Total number of electrons in energy level spdf 1 X 2 2 XX 8 3 XXX 18 4 xxxX 32

Electron Properties Pauli exclusion principle says that a maximum of 2 electrons may occupy a single atomic orbital but they must have opposite spins Hund’s rule- single electrons with same spin must occupy each equal-energy orbital before electrons with opposite spin can be added. Orbital diagram

Electron Configuration We can show the ground state electron arrangement for elements ▫Ground state: lowest state of energy for an electron

Electron Configuration First write a number (1-7) indicating the energy level Second write the orbital that corresponds with that energy level Third use superscripted numbers to indicate the number of electrons

1s 2 Energy level Orbital Number of Electrons

Electron configuration chart

Examples Electron configuration and orbital diagram for: ▫Magnesium, Sulfur, and Bromine ▫Elements: 3, 15, 26, 13, 36