1. The Atom Unit 4 Chemistry

2. DO NOW 11/16/15  Answer the following questions  What do you know about the atom (ex: what is it made of?)  How big is the atom?  How would you represent an atom on paper? Draw an atom:

3. Video  https://youtu.be/yQP4UJhNn0I https://youtu.be/yQP4UJhNn0I

4. The Atom  The atom is the smallest particle of an element that retains the chemical properties of that element.  Consist of smaller particles and their number and arrangement of these particles within the atom determine it’s chemical property  Consists of 2 regions

5. Atoms 2 regions 1) Nucleus: very small, located near the center of an atom 2) Electrons: surrounds the nucleus 1) Large region compared to nucleus Nucleus Electron shells

6. Subatomic particles  3 subatomic particles 1. Protons: positive charge Within nucleus 2. Neutrons: neutral charge 3. Electrons: negative charge

7. Atomic Anatomy The gas of an atomWhat they look like “Subatomic Particles”# e - = # p + (for neutral atoms) Particle (symbol) MassChargeLocation Proton P + 1+1nucleus Neutron n 0 10nucleus Electron e- 0Outside, orbiting the nucleus

8. Chemical Symbol Atomic # Symbol 1 st Letter 2 nd letter Name Average Atomic Mass # of p + + # n 0 # n 0 = mass –atomic # (round mass) 8 O Oxygen 15.999

9. Practice finding # e -, p + and n 0 7 N Nitrogen 14.01 11 Na Sodium 22.99 15 P Phosphorus 10.97

10. So how do we draw the atoms? Ex: Li – Three protons (atomic number) 3 Li Lithium 6.941 P+

11. Four neutron. (mass – atomic number n0n0 n0n0 n0n0 n0n0 p+

12. Three electrons, in two electron shells n0n0 n0n0 e- p+ e- ____p + ____n 0

13. Positions of electrons Shell ## of e- 12Go in as a pair 281 in each of 4 places then pair up 38 (sort of - more to come)1 in each of 4 places then pair up 48 (sort of – more to come)1 in each of 4 places then pair up

14. DO NOW 11/17/19  Draw a Bohr model of sodium 11 Na Sodium 22.990