Vocabulary

1. Vocabulary Bohr model Energy level (shell) Valence electrons

2. Bohr Model • Electrons orbit the nucleus of an atom in set energy levels P = 20 N = 20

3. Energy Level • The specific energies an electron in an atom can have • In the Bohr model used to describe the different orbits or shells that the electrons travel in around the nucleus

4. Valence Electrons • The electrons in the highest or outermost energy level

5. Bohr Models are NOT Boring! How to Draw Bohr Diagrams

6. Bohr models-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.

7. Bohr Diagrams • Find the 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.

8. Bohr Diagrams • Find out which period (row) your element is in. 1 2 3 4 5 6 7 • Elements in the 1st period have one energy level. • Elements in the 2nd period have two energy levels, and so on. www.chem4kids.com

9. The electron energy levels or shells surrounding the nucleus each hold a particular number of electrons. Energy levels or shells are represented by n= period number: n=1 max 2 electrons n=2 max 8 electrons n=3 max 18 electrons n=4 max 32 electrons Remember: The outer shell of an atom (no matter what letter) can only hold 8 electrons!

10. Max Electrons in each Energy Levels2 electrons in 1st, 8 electrons in 2nd, 18 electrons in the 3rd, 32 electrons in the 4th 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 P = N = 2 e 8 e 18 e 32 e

11. Max rule (2,8,18,32)Fill rule (2,8,8,2 then rest in 3rd)

12. Bohr Diagrams • Draw a nucleus. Write the number of Protons and Neutrons the element has inside the nucleus. P = 6 N = 6 Note: Round mass to nearest 1 when figuring neutrons.

13. Bohr Diagrams P = 6 N = 6 Carbon is in the 2nd period, so it has two energy levels, or shells. Draw the shells around the nucleus.

14. Bohr Diagrams • Add the electrons. Carbon has 6 electrons. The first shell can only hold 2 electrons. The second shell put the remaining 4 electrons P= 6 N = 6

15. Bohr Diagrams Try Hydrogen: Atomic Mass: Atomic Number: Protons: Electrons: Neutrons: Shells: Valence electrons: H P+ = N0 =

16. Bohr Diagrams Try Hydrogen: Atomic Mass: 1.008 Atomic Number: 1 Protons: 1 Electrons: 1 Neutrons: 0 Shells: 1 Valence electrons: 1 H P = 1 N = 0

17. Bohr Diagrams Check Yourself. H (1) P= 1 N= 0

18. Bohr Diagrams Try Helium Try Helium: Atomic Mass: Atomic Number: Protons: Electrons: Neutrons: Shells: Valence electrons: He P= N=

19. Bohr Diagrams Try Helium Try Helium: Atomic Mass: 4.003 Atomic Number: 2 Protons: 2 Electrons: 2 Neutrons: 2 Shells: 1 Valence electrons: 2 He P= 2 N= 2

20. Bohr Diagrams Check Yourself! He (2) P= 2 N= 2

21. Bohr Diagrams Try Oxygen: Atomic Mass: Atomic Number: Protons: Electrons: Neutrons: Shells: Valence electrons: O P+= N0=

22. Bohr Diagrams Try Oxygen: Atomic Mass: 15.999 Atomic Number: 8 Protons: 8 Electrons: 8 Neutrons: 8 Shells: 2 Valence electrons: 6 P= 8 N= 8

23. Bohr Diagrams Check Yourslef! O (2,6) P= 8 N= 8

24. Bohr Diagrams Try Aluminum: Atomic Mass: 26.982 Atomic Number: 13 Protons:13 Electrons:13 Neutrons:14 Shells:3 Valence electrons:3 P= 13 N= 14

25. Bohr Diagrams Check Yourself! Al (2,8,3) P= 13 N= 14

26. Bohr Diagrams Try Aluminum: Atomic Mass: 26.982 Atomic Number: 13 Protons:13 Electrons:13 Neutrons:14 Shells:3 Valence electrons:3 P= 13 N= 14

27. Bohr Diagrams Try Titanium (Ti) : Atomic Mass: 47.88 Atomic Number: 22 Protons: 22 Electrons: 22 Neutrons: 26 Shells: 4 Valence electrons: 2 P= 22 N= 26

28. Bohr Diagrams Check Yourself! Ti (2,8,10,2) P= 22 N= 26