Unit Test: Atomic Structure / History and Structure of the Atom

What does the atomic mass of an element represent?

The atomic mass describes a chemical element, protons, and neutrons.

What does the atomic number of an element represent? What does the mass number of an atom represent?

The atomic # represents the distinct identity of an element and number of protons The mass # represents the sum of protons and neutrons

State the 4 major ideas of Dalton's Atomic Theory

1. Matter is made up with atoms that are invisible and indestructible 2. All atoms of an element are identical 3. Atoms of different elements have different weights and different chemical properties. 4. Atoms of different elements combine in simple whole numbers to form compounds.

Describe the experiment that led to the discover of the electron. Who discovered it?

Experimented with Crookes, cathode ray, and a tube. The experiment showed that cathode rays were negatively charged. Joseph John "J.J." Thomson in 1897.

What are isotopes? How are they similar to each other? How are they different?

Isotopes are always, with the same number of protons but different number of neutrons. - they have the same number of protons - they have the different number of neutrons

Who discovered the Neutron.

James Chadwick

When was the idea of an atom first developed?

John Dalton, 1803.

What are the 3 subatomic Particles?

Proton, Neutron, and Electron.

Of protons, neutrons, and electrons, which of these can never change in atom during an ordinary chemical or physical change? Explain Why.

Protons, because if you change the amount of protons you would be changing the element.

Who determined the charge of the electron and during what experiment.

Robert A. Millikan during the Oil Drop Experiment.

Describe Rutherford's gold foil experiment. What did this experiment tell us about the structure of the atom?

Rutherford shot a beam of alpha particles at a sheet of gold foil. He concluded that a tiny, dense nucleus was causing the deflections.

Describe the Electron Cloud Model of the Atom. What are the smallest parts of an atom we know today?

The electron cloud model includes an electron cloud around the nucleus which contains neutrons and protons. 1. electrons 2. protons 3. neutrons

What is an ion? What are the two ways in which an ion can be made?

an atom with an electrical charge due to the loss or gain of electron. 1. the loss of an electron 2. the gain of an electron