1. The Atom - Atomic Structure: Subatomic Particles
Dr. Chin Chu
River Dell Regional High School

2. F. The Quantum Atom Theory
1. The atom is mostly empty
space
2. Two regions:
a. Nucleus- protons and neutrons
b. Electron cloud- region where you have a 90% chance of finding an electron

3. Subatomic Particles Electron Proton Neutron Name Symbol Charge
Comparing Particles
Electron
Proton
Neutron
Name
Symbol
Charge
Relative
mass
Actual
mass (g) e- -1
9.11 x 10-28 p+ +1
1amu
x 10-24 n0
1amu
x 10-24

4. Subatomic Particles B. Atomic Number and Mass Number
1. the number of protons in the nucleus of an atom
a. identifies the element
b. no two elements have the same atomic number
Ex. C is 6, N is 7 and O is 8
carbon nitrogen oxygen

5. Subatomic Particles B. Atomic Number and Mass Number
3. Since the atoms are neutral, the number of protons must equal to that of electrons.
atomic number = # of protons = # electrons
Ex. # of electrons in C is 6, in N is 7 and in O is 8

6. B. Atomic Number and Mass Number
a. the number of protons plus neutrons in the nucleus of an atom
b. mass number is very close to the mass of an atom in amu (atomic mass units)
c. two atoms with the same atomic number but different mass number are called isotopes
1) (mass #) – (atomic #) = #n 0

7. D. Changing Number of Particles
1. You can never change the number of
protons and have the same element
2. If you change the number of neutrons in an atom, you get an isotope
3. If you change the number of electrons in an atom, you get an ion

8. E. Nuclear Notation
Nuclear Notation is one method for depicting isotopes of an element
contains the symbol of the element, the mass number, and the atomic number
Mass number X
Atomic number

9. How many protons?
How many neutrons?
How many electrons? 23 Na 11

10. a. Fluorine-19 F. Hyphened Notation 1. Element symbol or name – mass #
2. EXAMPLES
a. Fluorine-19
b. C-14
c. U-238