Atomic Structure

Updating Dalton’s Model of the Atom

In the years after Dalton’s model was accepted, two important discoveries about atoms were made:

1.  Atoms CAN be broken down into smaller particles called ______

2.  There is a mass concentrated in the center of each atom, which is called the ______

Rutherford’s gold foil experiment (1911)

Rutherford now believed that atoms were made of:

1.  a tiny positive core

2.  surrounded by a large cloud of tiny, randomly orbiting, negative electrons.

Finally, in 1913, Niels Bohr used quantum physics to modify Rutherfords model

by explaining specifically where electrons fit into the atomic model.

Bohr was able to show that electrons were found in fixed ______, which could each hold a specific number of electrons.

Later work showed that the very dense nucleus of atoms was made up of two sub-atomic particles:

______and ______.

Most of the mass of the atom is found in the nucleus.

Summary of Sub-Atomic Particles:

Proton / Neutron / Electron
Relative mass
Relative charge

How many Subatomic Particles in each Element?

Using the Periodic Table we can determine exactly how many protons, neutron and electrons are found in each element.

Number of Protons = Atomic Number

Number of Electrons = # of Protons (overall neutral charge)

Number of Neutrons = Atomic Mass – Atomic Number

Example: Carbon (C)

Carbon has ______protons, ______electrons, and ______neutrons

Chlorine / Nitrogen / Sodium / Oxygen

Standard atomic notation: Try some:

Bohr-Rutherford Diagrams

All of this information can be shown visually in the form of a Bohr-Rutherford Diagram.

Let’s draw the Bohr Rutherford Diagram for Carbon

1
Atomic Notation:
Protons:
Electrons:
Neutrons: / 2
Atomic Notation:
Protons:
Electrons:
Neutrons: / 3
Atomic Notation:
Protons:
Electrons:
Neutrons: / 4
Atomic Notation:
Protons:
Electrons:
Neutrons: / 5
Atomic Notation:
Protons:
Electrons:
Neutrons:
6
Atomic Notation:
Protons:
Electrons:
Neutrons: / 7
Atomic Notation:
Protons:
Electrons:
Neutrons: / 8
Atomic Notation:
Protons:
Electrons:
Neutrons: / 9
Atomic Notation:
Protons:
Electrons:
Neutrons: / 10
Atomic Notation:
Protons:
Electrons:
Neutrons:

Bohr-Rutherford Diagrams

11
Atomic Notation:
Protons:
Electrons:
Neutrons: / 12
Atomic Notation:
Protons:
Electrons:
Neutrons: / 13
Atomic Notation:
Protons:
Electrons:
Neutrons: / 14
Atomic Notation:
Protons:
Electrons:
Neutrons: / 15
Atomic Notation:
Protons:
Electrons:
Neutrons:
16
Atomic Notation:
Protons:
Electrons:
Neutrons: / 17
Atomic Notation:
Protons:
Electrons:
Neutrons: / 18
Atomic Notation:
Protons:
Electrons:
Neutrons: / 19
Atomic Notation:
Protons:
Electrons:
Neutrons: / 20
Atomic Notation:
Protons:
Electrons:
Neutrons: