# The Atom - Atomic Structure: Subatomic Particles

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

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

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

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

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

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

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

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

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

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