1. ATOMS AND ATOMIC STRUCTURE Atom Nucleus Proton Neutron Electron

2. WHAT IS AN ATOM? The smallest unit of an element.
Consists of a nucleus surrounded by one or more electrons.

3. How small is an atom?

5. WHAT IS THE NUCLEUS? Central part of an atom.
Made up of protons and neutrons.
Contains most of an atom's mass.

6. WHAT IS A PROTON? Positively charged particle.
Found in atom’s nucleus.
Subatomic particle that defines the element.
Same as the atomic #!

7. WHAT IS A NEUTRON? Uncharged particle. Found within an atomic nucleus.
Mass number – atomic number = number of neutrons!

8. WHAT IS AN ELECTRON? Negatively charged particle.
Located in shells that surround an atom's nucleus.
Equal to the number of protons in a neutral atom.

9. Electron Cloud
They are constantly in motion, so their exact location at any time is hard to determine!

10. Valence Electrons Electrons in the outermost energy level of an atom!
Responsible for atom’s behavior/bonding!

11. Build an Atom

12. Ion Atoms that are no longer neutral! Have lost or gained electrons!
So…
# of protons and # of electrons are NOT equal

13. Isotopes Atoms of the same element with different numbers of neutrons.
May be stable or unstable!