chapter 3

4 characteristics of electrons that were determined by experiences by thomas and millikan?

1. Cathode rays are composed of identicslly negatively charged particles, electrons. 2. atoms must contain a positive charge to balance the negative electrons 3. electrons are so small so the atom must have other particles for account of most of the mass 4. electrons have a large charge to mass ratio

Summarize Rutherford's model of an atom, and explain how he developed this model based on the results of his famous gold-foil experiment.

Rutherford shot alpha particles at gold foil. If Thompson was right, the atoms would bounce off the foil. But that did not happen, in fact the particles went straight through.

how are isotopes of a particular element alike? Different?

The isoptopes of a particular element still have the same number of protons and electrons, the only thing that changes is the neutrons. They are different because there number of neutrons are different

What is the molar mass of an element?

The mass of one mole of a pure substance

What is the mass number of an isotope?

The number of protons and neutrons

What is the atomic number of an element?

The number of protons in that element.

What is a nucleotide?

The term for a specific isotope of an element

What are isotopes?

atoms of the same elements that have different masses

2 regions that make up all atoms?

electron cloud and nucleus

What is an atom?

smallest particle of an element

What is a mole?

the amount of a substance that contains as many particles as there are atoms in exactly 12g of carbon-12

What number uniquely identifies an element?

the atomic number