1. Topic: Atomic Concepts Aim: What is the structure of an atom
Topic: Atomic Concepts Aim: What is the structure of an atom? Do Now: (from the August 2007 Regents)
HW:

2. Subatomic Particles Every atom has Protons Neutrons Electrons
Nucleus overall positive charge
surrounded by electrons  negative charge
Protons
Neutrons
Electrons

3. Subatomic Particles Location Charge Symbol Mass Proton Nucleus + p+
1 amu
Neutron
neutral n0
Electron
Electron cloud – e-
1/1840 amu

4. Determining the # of p, n, & e from the Periodic Table
Average Atomic Mass (round for Mass #)
Mass # = # p+ + # n0
Atomic Symbol
Atomic # = # of protons (in nucleus)
Also # of electrons (in a neutral atom)
# of + protons = # of – electrons

5. Example
Now, answer the same 3 questions for Lithium, Nitrogen, and Potassium.
An atom has 15 protons & 16 neutrons. What is its atomic number? What is its mass number? What element is this?
How many protons?
How many electrons?
How many neutrons?

6. Complete Symbols
How many protons? Electrons? Neutrons?

7. Examples

8. How many p, n, & e?
Pu-244
Am-241
Ac-227
Cs-133
Ir-193
Mn-56

9. Complete the chart… Name Symbol Atomic # Mass # Neutrons Sodium 11 23
Nitrogen
157N
13656Ba
Lithium 6
Boron 5

10. Practice Problem (August 2007)
The_Atom.asf (5 min)

11. June 2009
1 Which subatomic particle is negatively charged? (1) electron (3) positron (2) neutron (4) proton 3 What is the mass number of a carbon atom that contains six protons, eight neutrons, and six electrons? (1) 6 (3) 14 (2) 8 (4) 20