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Science 404
September 10th, 2012
Atom Structure
Textbook Chapter 1
(Pages 10-17)
Atom Structure
The atom is the basic building block of matter. It is the smallest unit of a chemical
matter and it is composed of three elementary particles: _________________,
_______________, ____________________
The protons and neutrons form the core of an atom called the nucleus, while the
electrons exist outside of the nucleus and in the orbitals.
Here is a basic summary of the subatomic particles (neutrons, protons and electrons)
Subatomic Particle
Location
Electron
Electron Orbitals
Proton
+1
Electrons
• Electrons are negatively charged particles
• Electrons are located in a region of space that is outside the nucleus called orbitals.
•
The valence electrons are farthest from the nucleus
• They were discovered by J.J. Thomson
Neutrons
• Neutrons are electrically neutral (no charge) particles that are located in the nucleus
Protons
• Protons are positively charged particles located in the nucleus
Atomic Number
• Atomic Number (Z): __________ of ____________ in the nucleus of each atom of
a given element
•
In a neutral atom:
Atomic number will also indicate the number of _____________
Atomic Weights
Atomic Weight represents the ________ of an atom.
• It is the weight in grams of one mole (mol) of the mass of a given element
•
It is expressed in terms of ___ /____
How to calculate protons, electrons, neutrons in a
neutral atom?
Protons are = atomic number
Electrons are = number of protons
neutrons are = atomic mass – atomic number
Example for Helium
Protons = 2
Electrons = 2
neutrons = 2
Questions?
How many protons, electrons and neutrons does carbon have?
How many protons, electrons and neutrons does nitrogen have?
How many protons, electrons and neutrons does oxygen have?
How many protons, electrons and neutrons does silicon have?
How many protons, electrons and neutrons does phosphorous have?
How many protons, electrons and neutrons does sulfur have?