Chemistry--Unit 4: Atomic Structures

Dalton’s Experiment

Atomic Theory:

1) Elements consist of invisible particles called atoms.

2) Atoms of the same element are identical.

3) Law of Conservation of Mass: Atoms cannot be created nor destoyed.

4) Law of Multiple Proportions: Atoms combine in whole number ratios: compounds.

Dalton’s model of the atom

Dalton’s Experiment

Atomic Theory:

1) Elements consist of invisible particles called atoms.

2) Atoms of the same element are identical.

3) Law of Conservation of Mass: Atoms cannot be created nor destoyed.

4) Law of Multiple Proportions: Atoms combine in whole number ratios: compounds.

Dalton’s model of the atom

Thompson’s Experiment

Discovered electrons through his cathode ray tube test

1) Beam must contain negative charges since it’s repelled by the negative end of the magnent

2) If an atom has negative particles, it should also have positive particles

3) All matter is made up of positive and negative particles—he tested multiple samples and found similar results

Thompson’s model of the atom

Rutherford’s experiment

Discovered the nucleus through his gold foil test

1) Accurately predicted that most particles would pass through the foil, concluding that most of the atom is empty space

2) Small percentage bonced back, so the atom must have a small, positive center, since positive charges repelled one another

Rutherford’s model of the atom

Millikan’s experiment

Oil drop experiment

1) Found the charge and mass of a single electron

2) Charge is greater than mass

Bohr’s experiment

Discovered electron energy levels

1) Worked with hydrogen emission spectors, and modeled the atom

2) Found out that electrons would jump between energy levels based on whether it gains or loses energy

Bohr’s model of the atom

Schrödinger’s experiment

Discovered a quantum model

1) Found a mathematical equation for predicting an electron’s position

2) Created an orbital shape for electrons

Schrödinger’s model of the atom

What is a proton?

A positively charged particle in the nucleus

What is a neutron?

A neutral atom particle in the nucleus

What is an electron?

A negative particle found outside of the nucleus

What is the atomic number?

The number that represents the number of protons in an element and determines its identity

What is atomic mass?

The number at the bottom of the box that represents the average mass of all isotopes of that element

What is an element symbol?

A 1 or 2 letter symbol representing the element’s name

What is an ion?

A charged particle that has either gained or lost electrons

What is a cation?

A charged particle that has lost electrons. Positvely charged

What is an anion?

A charged particle that has gained electrons. Negatively charged

What is an isotope?

An atom that has more or less neutrons, which changes its mass

What notation is this represented in?

Isotope notation

What notation is ‘Hydrogen—3’ represented in?

Hyphen notation

What is the difference between mass number and atomic number?

The mass number is the total number of protons and neutrons.

The atomic number is the amount of protons.

What is the average atomic mass?

The weighted mass

The average mass of all isotopes of an element

What is the formula for average atomic mass (AAM?)

What is the equatio to find the percentage of abundance of an element?