Chemistry

Democritus

Democritus

Proposed matter was not infinitely divisible Atoms move through empty space Coined the term ATOMOS

ATOMOS

indivisible

Aristotle

Rejected Democritus' idea Believed atoms were made of elements Wrong, but theory held for 2000 years

John Dalton

School Teacher of England Made an Atomic theory

Dalton's atomic theory

Matter is made of small particles called atoms Atoms are indivisible and indestructible Atoms of the same element are identical In reactions, atoms are separated, rearranged, and combined

Atom

The smallest particle of an element that retains the property of the element

JJ Thompson

Discovers electrons

Millikan

Determines the charge of the electron

Rutherford

Determined that Atoms are mostly empty space Discovered the existence of a nucleus Discovers the existence of a proton

Who made the Plum Model?

JJ Thompson

Who made the model involving Gold?

Rutherford

Chadwick

Discovers the Neutron

Niels Boh

Publishes theory of atomic structure Concluded that electrons must orbit the nucleus, protons, and neutrons.

Schrodinger

Quantum Mechanical Model of the Atom

Qualities of the Proton

In the Nucleus +1 charge 1 amu in mass symbol p+

Qualities of the Neutron

In the Nucleus 0 charge 1 amu in mass symbol n0

Qualities of the Electron

Outside the Nucleus in the Electron Cloud -1 Charge 0 amu in mass symbol e-

Amu

Atomic mass unit

Isotopes

Unique types of an element with different numbers of neutrons, but the same number of protons and electrons

Example of an Isotope

Carbon 12: 6 protons, 6 neutrons, 6 electrons Carbon 13: 6 protons, 7 neutrons, 6 electrons

Atomic number

Is equal to the number of protons of an element Is the identifying number on the periodic table

Atomic Mass

Is the weighted average of the mass of the isotopes for an element Is the decimal number on the periodic table

Why is atomic mass a weighted average?

This is because different isotopes have different masses

Mass Number

The protons plus the neutrons of an atom

What are the two ways isotopes are displayed?

Name-Mass number AZE Notation

AZE notation

A- Mass number Z- Atomic number E- Chemical Symbol

Subatomic Counts

of protons- Atomic number

of electrons= #of protons

of neutrons+ # of electrons= Mass number

Two types of Nuclear Reactions

Fission Fusion

Nuclear Chemistry

The study of the changes that occur inside the nucleus of an atom

From the nuclei of radiation isotopes

Where do some elements release radiation?

Negatives of Radiation

Cam cause cancer and other illnesses

Positives of Radiation

Can kill parasites in food sources Can be used on food to extend food life Can be used as tracers in research

Nuclear Reaction

What happens when the nucleus of an atom undergoes a change?

When does the atomic number change?

Anytime a particle is absorbed or released for the nucleus of an atom

Qualities of the Alpha Particle

4 amu in mass +2 in charge Very Low Penetration No Biological Hazard unless inhaled Equivalent to a helium 4-nucleus Emitted during Radioactive decay

Qualities of the Beta Particle

0 amu in mass -1 Charge Low Penetration Biological Hazard to skin and eyes Very Fast Emitted during Radioactive Decay

Qualities of the Gamma Particle

0 Mass 0 Charge Very High Penetration Biological Hazard to whole body; causes mutations Accounts for most of the energy lost during radioactive decay Does not add or subtract to the number of protons, neutrons, and electrons.

What happens during Alpha decay?

A particle made of 2 protons and 2 neutrons is ejected from the nucleus. Essentially subtracts 2 protons and 2 neutrons form an element.

What happens during Beta Decay?

A neutron is broken down into a proton and a beta particle (which is essentially an electron) and the beta particle is ejected from the nucleus at high speeds. The original Neutron becomes a proton and changes the atomic number. Essentially subtracts a proton from an element.

What happens during Gamma Emission?

The nucleus has too much energy and releases them as electromagnetic waves.

What is Gamma?

A form of electromagnetic energy that has no mass

What determines stability in an atom?

The ratio of protons to neutrons.

Chemical Reaction

A process in which a new substance is created from an already existing substance

How is the atomic mass found?

Calculating the averages of the isotopes of an element.

What is the difference between a chemical reaction and a Nuclear reaction?

A chemical reaction involves the redistribution of electrons in an atom to create a new substance, as we know the electron is outside of the nucleus of an atom. A nuclear reaction is the change of the nucleus of an atom, involving protons and electrons.

Radioactivity

The process in which some substances spontaneously emit radiation

Radioactive Decay

A spontaneous process in which unstable nuclei lose energy by emitting radiation

Why are some atoms radioactive and others are not?

This is because Radioactive atoms emit radiation because their nuclei is unstable.