1. Topic: Structure of an Atom
Essential Questions
What makes up an atom?
What is inside the atom?

2. What Is an Atom? Atom  building blocks of matter.
 have a nucleus surrounded by an
electron cloud
Atoms are composed of smaller subatomic particles
A.) proton
B.) neutron
C.) electron.
Each element is composed of one type of atom and can not be broken down into a simpler substance

3. Structure of an atom

4. Inner Structure of an Atom
Nucleus - Small, dense, positively charged center of the atom which contains most of the atom’s mass
The nucleus contains subatomic particles have certain characteristics:
Protons - positively charged particles in the nucleus of the atom +
Neutrons - particles in the nucleus that have no charge but contribute to the atom’s mass NEUTRAL 0

5. Outer Structure of an Atom
Electron cloud - an area encircling the nucleus where electrons are likely to be found
The cloud contains energy levels (electron shells)
electrons are negatively charged particles located in specific energy levels

6. Outer Structure of an Atom
Energy levels completely surround the nucleus
Maximum of 2 electrons
Nucleus
Maximum of 8 electrons
Maximum of 18 electrons
Maximum of 32 electrons
Maximum of 50 electrons

7. Outer Structure of an Atom
Valence electrons  are found in the outermost energy level (LAST SHELL)
 involved in Chemical bonding
valence is the number of bonds an
atom can form
an atom is most stable when its outermost energy level is full =8 electrons

8. Atom Characteristics
Atomic Number  the number of protons in the nucleus of that atom.
Neutral atom the number of protons (+) equals the number of electrons (-)
Atomic mass is the mass of the protons plus the mass of the neutrons

9. Decoding Atom Information
carbon 6
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# of protons
Atom’s
symbol
Atom’s name
Atomic
mass

10. Decoding Atom Information cont:
# of protons = # of electrons 6 C
carbon
Atomic mass = # of protons plus the # of neutrons
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