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October 29th, 2015
• Start Atomic Structure & Periodic Table
Bell Ringer
•Get homework out on your desk.
Today’s Purpose:
1. Describe the present model of the atom.
Matter and atoms
Matter:
• Anything that has mass and takes up space.
• All matter is made up of atoms.
Matter and atoms
Atom:
•Basic building block of matter
•Cannot be broken down further without changing the properties of that element
•The smallest unit of an element
Different types of atoms are called elements.
All matter is made of the atoms of approximately 118
elements.
Iron 5%
Earth’s Crust
Oxygen47%
Silicon28%
Aluminum 8 %
Other12%
Humans
Other 3%
Nit rogen 3%
SOURCE: CRC H andbook of Chemistr y and Physics
Oxygen61%
Carbon23%
Hydrogen 10%
Atom Concentrations by Mass
Chemical symbols
A chemical symbol is an abbreviated way to write the name of an element.
For example:
C =
H =
Fe = Iron
Hydrogen
Carbon
Chemical symbols
Chemical symbols always consist of one capital letter or a capital letter plus one or two
small letters.
C Cl CSCs
neutron
electron cloud
nucleus proton
Atoms are made of protons, neutrons, and electrons.
Nucleus – the central region of an atom where most of the atom’s mass is found in protons and neutrons.
Atoms are mostly empty space.
The radius of a atom is about 100,000 times larger than the radius of its nucleus.
If a basketball represented a nucleus…that atom would have a radius of 7.5 miles!
Protons: Positive (+) charge, mass = 1, indicates identity of atom
Neutrons: Neutral (0) charge, mass = 1
Electrons: Negative (-)charge, mass = 1/2000
Found inside
nucleus
Found outside nucleus
B5
Boron
Atomic Number = Number of protons
Boron has 5 protons
Mass Number = Protons + Neutrons
Protons = 7
+ Electrons = ?
N+3
7
+3
4
Charge = +3
Protons = 35
+ Electrons = ?
Br-1
35
36
Charge = -1
Protons = 25
+ Electrons = ?
Mn25
25
Charge = 0
Matter and atoms
Nucleus (+ charge)
Electrons (- charge)
- “orbit” the nucleus
Proton (+)
Neutron (No charge)
Models of the atom
Assignments
• Book reading chapter.
• Atomic Structure (ws)
• Quiz on elements Wednesday, November 4th