Warm-Up 11/6/13 Review: What are the outermost particles of an atom? How can you determine how many electrons an atom has? How many electrons do each of the noble gases (except He) have? What is the largest number that each of these values are divisible by?

The Bohr Model Wednesday 11/6/13

Dalton’s Atomic Model

Plum Pudding Model (Thomson)

The Bohr Model

Niels Bohr (Born in Denmark 1885-1962) Student of Rutherford

Niels Bohr’s Model (1913) Electrons orbit the nucleus in circular paths of fixed energy (energy levels).

Niels Bohr’s Atom Cont’d Electrons can jump from energy level to energy level. Electrons absorb or emit light energy when they jump from one energy level to another.

Quantum A quantum of energy is the amount of energy required to move an electron from one energy level to another.

Drawing Bohr Diagrams Find your element on the periodic table. Determine the number of electrons – it is the same as the atomic number. This is how many electrons you will draw.

Bohr Diagrams Find out which period (row) your element is in. Elements in the 1st period have one energy level. Elements in the 2nd period have two energy levels, and so on. www.chem4kids.com

C Bohr Diagram--Carbon Draw a nucleus with the element symbol inside. Carbon is in the 2nd period, so it has two energy levels, or shells. Draw the shells around the nucleus. C

C Bohr Diagram--Carbon Add the electrons. Carbon has 6 electrons. The first shell can only hold 2 electrons. C

Bohr Diagrams--Carbon Since you have 2 electrons already drawn, you need to add 4 more. These go in the 2nd shell. Add one at a time -starting on the right side and going counter clock-wise. C

C Bohr Diagrams Check your work. You should have 6 total electrons for Carbon. Only two electrons can fit in the 1st shell. The 2nd shell can hold up to 8 electrons. The 3rd shell and up can hold 18, but the elements in the first few periods only use 8 electrons. C

Your Job Complete the Bohr Model Worksheet for tomorrow. Use the same format for drawing the Bohr Diagrams as you saw in the notes (symbol in the middle, draw the shells, and add dots for electrons)