They aren’t just bohr-ring drawings! Bohr models They aren’t just bohr-ring drawings!

Bohr models are a simple way to draw an atom Bohr models are a way of showing the electrons in an atom. Electrons are arranged in energy levels. In actual atoms, those energy levels are clouds of crazy shapes where the electrons are likely to be found. Bohr models show the electron energy levels in nice, neat, easy to draw circles.

The Nucleus Draw a circle in the middle of your drawing to represent the nucleus. Write the number of protons and neutrons in the nucleus. _6_P _6_N # Protons = atomic # # Neutrons = mass – atomic # 12 - 6

Bohr Diagrams Find out which period (row) your element is in. Elements in the 1st period have one shell. Elements in the 2nd period have two shells, and so on. *The period (row) determines the # of rings. www.chem4kids.com

Bohr Diagrams Draw a nucleus showing the number of protons and neutrons. Carbon is in the 2nd period, so it has two energy levels, or shells. Draw the shells around the nucleus. 6P 6N

Bohr Diagrams *Find your element on the periodic table. Determine the number of electrons – look at the atomic number. *This is how many electrons you will draw.

1st energy level (2 electrons) Draw the first ring of electrons around the nucleus. Only 2 electrons can fit in this energy level 2 e ___P ___N

2nd energy level (8 electrons) Draw the second ring of electrons around the nucleus. Only 8 electrons can fit in this energy level ___P ___N 2 e 8 e

Bohr Diagrams 6P 6N Add the electrons. Carbon has 6 electrons. The first shell can only hold 2 electrons. 6P 6N

Bohr Diagrams 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. 6P 6N

3rd & 4th energy levels (18 electrons in the 3rd, 32 electrons in the 4th Draw the next 3rd and 4th ring of electrons around the nucleus. 18 electrons can fit in the 3rd energy level and 32 electrons can fit in the 4the energy level ___P ___N 2 e 8 e 18 e 32 e

Draw dots to represent electrons Figure out how many electrons are in the atom you want to draw. Put 2 dots on the 1st ring. Put up to 8 dots in the 2nd ring. Put up to 18 electrons in the 3rd ring. Things get a little crazy in the 3rd and 4th rings…8 go into the 3rd, then the next 2 go into the 4th, then the electrons go back and fill up the 3rd.

Bohr Practice Try the following elements on your own: H He O Al Ne C

Bohr Diagrams Try the following elements on your own: H – 1 electron Al Ne 1P 0N

Bohr Diagrams Try the following elements on your own: H He - 2 electrons O Al Ne 2P 2N

Bohr Diagrams Try the following elements on your own: H He O - 8 electrons Al Ne 8P 8N

Bohr Diagrams Try the following elements on your own: H He O Al - 13 electrons Ne 13P 14N

Bohr Diagrams Try the following elements on your own: H He O Al Ne - 10 electrons K 10P 10N

Bohr Diagrams Try the following elements on your own: H He O Al Ne K 19P 20N

Bohr Diagrams Try the following elements on your own: g) Be h) N i) P j) Cl k) Ca l) Kr (challenging!)

Bohr Diagrams 4P 5N Try the following elements on your own: g) Be - 3 electrons h) N i) P j) Cl k) Ca l) Kr 4P 5N

Bohr Diagrams 7P 7N Try the following elements on your own: g) Be h) N - 7 electrons i) P j) Cl k) Ca l) Kr 7P 7N

Bohr Diagrams 15P 16N Try the following elements on your own: g) Be h) N i) P - 15 electrons j) Cl k) Ca l) Kr 15P 16N

Bohr Diagrams 17P 18N Try the following elements on your own: g) Be h) N i) P j) Cl - 17 electrons k) Ca l) Kr 17P 18N

Bohr Diagrams 20P 20N Try the following elements on your own: g) Be h) N i) P j) Cl k) Ca - 20 electrons l) Kr 20P 20N

Bohr Diagrams 36P 48N Try the following elements on your own: g) Be h) N i) P j) Cl k) Ca l) Kr – 36 electrons (2-8-18-8) 36P 48N

Bohr Diagrams You should be familiar enough with these diagrams to draw a Bohr model for the first 20 elements.

Magnesium Bohr Model *Put 2 dots on the 1st ring. *Magnesium has 12 electrons *Put 2 dots on the 1st ring. *Put 8 dots in the 2nd ring. *Put the rest of the electrons in the 3rd ring.

Draw Bohr models of the following elements: Bohr Model Practice Draw Bohr models of the following elements: 1. lithium 2. sodium 3. carbon 4. neon 5. chlorine 6. nitrogen