Atomic Theory

Who discovered the Neutron?

James Chadwick

Who discovered the electron?

J.J Thomson

Who discovered the nucleus? 

Ernest Rutherford

Who determined that matter is made up of particles so small and indestructible that they cannot be divided into anything smaller

John Dalton

a. All matter is made of atoms. Atoms are indivisible and indestructible.

b. All atoms of a given element are identical in mass and properties.

c. Atoms of different elements have different properties.

d. Compounds are composed of atoms of more than one element. The atoms of a given compound are combined in a fixed numerical ration.

e. A chemical reaction involves the separation, combination, or rearrangement of atoms; it does NOT result in their creation or destruction.

Choose the two that are not true 

A: Atoms CAN be divided into subatomic particles (ex: Neutrons, Protons)

B: Isotopes can have different mass in a given element

What experiment did JJ Thomson use to make his observations and what conclusions did he make from his observations?

He used the Cathode Ray Tube Experiment to discover the electron

Briefly describe the gold foil experiment used by Ernest Rutherford.

He shot Alpha particles at a thin sheet of gold foil. Most of the particles passed through the foil, while some were deflected.

Describe why we no longer  use the Bohr model of the atom.

Electrons do not move in fixed planetary orbits around the nucleus and it only works with the hydrogen atom.

What is the electron probability cloud?

A region where electrons are most likely to be found (90% of the time)

Dalton and Democritus

No name for this model with no subatomic particles. No experiment and the first model.

J.J Thomson

Plum pudding model. Electrons randomly in a positive sphere. Cathode Ray Tube experiment. 2nd model.

Ernest Rutherford

Rutherford model/Nuclear model. Electrons surrounding a small dense nucleolus. Gold foil experiment. 3rd model.

Niels Bohr and James Chadwick.

Bohr/ Planetary model. Electrons travel in orbits around a nucleus that has protons and neutrons. No experiment. 4th model.

Many Scientists

Electron cloud/ Quantum model. Electrons are in a cloud surrounding a nucleus that contains Protons and Neutrons. No experiments. Final model we use today.

Atomic Number

Number of protons

Neutron

Atomic mass - number of protons

Mass number

Protons + Neutrons

Electrons

Equal to number of protons

Protons

Atomic Number

How are isotopes of the same element alike?

Same number of protons and same atomic number

How are isotopes of different elements alike.

Different mass number and different number of neutrons

How to find Average Atomic Mass

AMU * Abundance (But move the decimal point two places to the left and if the abundance is like 8.823 it becomes 0.0823) Then add all them up to find the average atomic mass.

How to find Half Life

The time required for half of the radioactive atoms in a sample to decay. It is a characteristic property of each radioactive isotope.

Alpha Decay

The emission of a helium atom out of/from the nucleus of another atom.

When it is element → Alpha Decay then you minus. BUT if it is element + Alpha Decay then you add to find original element.

To find alpha decay first minus 4 from the mass number and 2 from the atomic number of the element.

Beta Decay

Transformation of a neutron in the nucleolus into a proton and electron and the electron gets ejected from the atom

To start you minus NOTHING from the atomic mass but add one to the atomic number even though it says -1. Same thing with alpha decay in matters of placement of arrow.

Gamma Decay

Emission of large amounts of energy (Photons)

nothing changes.