Be respectful no electronics please Announcements n n

Be respectful – no electronics please! Announcements n n Pre/post lecture assignments due as usual Tuesdays & Thursdays at 8: 00 am Textbook homework due Friday

Take Homes: Atomic Structure A brief progression: Dalton Bohr Thomson & Thompson Rutherford

Clicker #1 How many of the following statements about atomic theory are still believed to be true? I. All atoms of the same element are identical. II. Negatively charged particles are embedded in a positively charged cloud throughout the atom. III. As verified by Rutherford, only positively charged particles called protons are found inside the nucleus. IV. J. J. Thomson provided the first experimental support for the atom. A) 0 B) 1 C) 2 D) 3 E) 4

Niels Bohr Model http: //abyss. uoregon. edu/~js/cosmo/lectures/lec 08. html

Take Homes: Niels Bohr Model n Electrons: n n Organized in discrete, quantized energy levels positioned outside the nucleus of the atom. Naturally positioned as close to the nucleus of the atom as possible (ground state. ) Can move from one energy level to a higher level with the addition of energy, but are never located between levels. The positioning of energy levels and the number of electrons in unique for each element.

Take Homes: Niels Bohr Model n n n Adding energy to an electron excites it, making it move further from the nucleus of the atom. To regain stability, an electron releases energy (often in the form of light) to return it to a lower energy level. Electrons orbit the nucleus of the atom in fixed paths.

What do you need to soak a cucumber in to make a pickle? 1. 2. 3. 4. 5. Na+ Cu+ K+ Li+ Be+2

Electrons n n Electrons are most likely to be found near the nucleus Electrons could be anywhere (very far even) We do not know how the electron moves ORBITALS = regions of 90% probability

Clicker #2 How many electrons can fit in a set of d orbitals in the third energy level? How many electrons can fit in a set of f orbitals in the fourth energy level? A) 1; 1 B) 2; 2 C) 5; 7 D) 10; 14 E) 15; 28

Electron Configurations and the Periodic Table n=1 H n=2 Li Be He B C

Clicker #3 Why is diagram #1 preferred over diagram #2? diagram #1 A) B) C) D) diagram #2 Because spreading out between orbitals of equal energy will minimize electron-electron repulsions. Because each orbital “wants” an electron and this way two of the orbitals will be “happy”. Because this way there are fewer electrons in the element so the nucleus can have a greater positively charged pull overall. Because this arrangement allows us to better predict the wavelength (and thus color) of light that will be emitted to return to its ground state.

Electron Configurations and the Periodic Table n=3 Na

Electron Configurations and the Periodic Table n=4 K

Electron Configurations and the Periodic Table S Mn

Clicker #4 - Sulfur 1. 2. 3. Give the complete ground state electron configuration for sulfur. Use the noble gas shorthand method to give the electron configuration for sulfur. Determine the number of unpaired electrons an energy diagram of sulfur is likely to contain. A) 0 B) 1 C) 2 D) 3 E) 6

Valence Electrons n Highest or outermost energy level electrons n n n Where the chemistry happens! Look at principal quantum level n Sulfur: 1 s 22 p 63 s 23 p 4 n n Valence electrons are in n = 3 level Valence electrons = 2 + 4 = 6 electrons

Cat Video and Alkali Metals http: //www. youtube. com/watch? v=fzzjg. BAa. WZw https: //www. youtube. com/watch? v=uixx. Jt. JPVXk (minute 1: 00)