1. Bohr model of a helium atom
Atomic Structure
Bohr model of a helium atom
-An atom consists of a nucleus made of protons and neutrons that is orbited by electrons

2. Atomic Structure
-The number of protons, not electrons or neutrons, determines the unique properties of an element
-The number of protons is called the element’s atomic number
-Most of the time, the number of protons will be the same as the number of electrons

3. Atomic Structure
-The size of a nucleus is very small (10,000 to 100,000 times smaller than the atom), but the nucleus contains almost all the mass (protons + neutrons).
-The electrons occupy a large area around the tiny nucleus, and this is what determines the size of an atom.
If the nucleus (1 proton) of a hydrogen atom were as large as the width of a human thumb, the electron would be on the average about a little more than half a mile away with only empty space in between

4. Atomic Structure

5. Atomic Structure Subatomic Particles p+ e- n0 proton electron neutron
Symbol p+ e- n0
Charge +1 -1
Mass 1
1/1837

6. Elements on the Periodic Table
atomic number
element symbol
element name
atomic weight
Label the four parts of this element.