Atoms and Nuclear Decay

Smallest particle of an element that retains the properties of the element

The number of electrons

A negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atoms nucleus

A subatomic particle carrying a charge equal to but opposite that of an electron

A subatomic particle that has a mass nearly equal to that of a proton but carries no electric charge

Matter is composed of extremely small particles called atoms

A model that consisted of a spherically shaped atom composed of a uniformly distributed positive charge in which the individual negatively charged electrons recited

And Adam consisted mostly of empty space through which the electrons move; almost all of the items positive charge and almost all of its mass were contained in an atom; the negatively charged electrons are held within the atom by their attraction to the positively charged nucleus

Nucleus

James Chadwick

Nucleus

Niels Bohr

Atoms with the same number of protons but different number of neutrons

Some of the atomic number or protons and neutrons

Atomic number on bottom

The atomic number is the same as the proton number

+1

Mass number minus proton or electron number

0

Number of electrons equals the number of protons or atomic number

-1

Can be observed without chemically changing matter

Describe how a substance interacts with other substances

Definite shape and definite volume; particles packed together

In definite shape and definite volume; particles have a room to move

Indefinite shape and in definite volume; particles far apart

No change an identity of a substance

One or more new substances produced

Physical change

Intensive or extensive

Positive

He said atoms were the smallest particles of matter. He said atoms cannot be destroyed or divided. He thought atoms were hard spheres that were the same throughout. His model was similar to a marble.

This scientist discovered the electron. His model of the atom was a sphere of positive charge with negatively charged particles spread evenly throughout.

He discovered the nucleus of the atom. He also determine that the nucleus was small and dense. It made up most of the mass of the atom. He propose that most of the atom was made up of empty space (he experimented with alpha particles and gold foil)

This 20th century scientist worked on a theory to explain how electrons are arranged in the atom. He proposed the idea that energy levels or shells housed the electrons which he thought moved around the nucleus much the way is planet orbits the sun.

He worked with Ernest Rutherford and was credited for discovering the neutron. The neutron was proposed one Rutherford's model could not explain why the nucleus was two times the mass of the number of protons

This is the most current model. It states that electrons are in constant motion around the nucleus. This motion is unpredictable and can't be described by an orbit. The new model simply defines a region where the electrons are most likely to be found.

Two protons and two neutrons

It goes down by 4

It goes down by 2

It is the element that is created after nuclear decay

Helium

It changes from a neutron to a proton and an electron

It is emitted after being transformed from a neutron

Means that an atom has a tendency to undergo spontaneous nuclear decay

The mass number stays the same

The atomic number of an atom will go up by 1

A type of antimatter equivalent to an electron

A proton is transformed into a neutron and a positron

The mass stays the same

The atomic number goes down by 1

An electron is absorbed into the nucleus which causes a proton to transform into a neutron

It stays the same

It goes down by 1

A proton is changed into an neutron in both types of decay