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Atoms and Elements
The periodic table
Periodic Trends
Nuclear Stability
Nuclear Radiation
100

The basic unit of matter.

Atom

100
This measurement determines the placement of an element on the periodic table.

Atomic number (number of protons)

100

This Russian chemist created the first periodic table based on observable properties. 

Dmitri Mendeleev

100
These particles are released through radioactive decay.

Radiation

100

When a parent nuclide divides into more stable daughter nuclides, often releasing excess neutrons. 

Nuclear fission

200

Elements are categorized into three main groups. Metals, nonmetals, and ____.

Metalloids

200

One or more atoms of the same element that have different numbers of neutrons.

Isotopes

200

One-half the distance between nuclei of identical atoms that are bonded together.

Atomic radius

200

All elements heavier than this are radioactive. 

Lead

200

This particle is released during alpha decay as a high energy helium nucleus. 

Alpha particle

300

While many elements undergo chemical changes to fill their valence electrons, this group of elements does not.

Noble gases

300

The measurement of both neutrons and protons.

Mass number

300
The amount of energy required to remove an electron from an atom. 
Ionization Energy
300

Oppositely charged particles are attracted through this force. 

Electrostatic force

300

This type of decay releases a charged particle when a neutron or proton are converted into the other. 

Beta Decay

400

The Gold Foil experiment proved the existence of what within the atom?

The nucleus

400

1/12th the mass of an atom of Carbon-12. The unit of mass for atoms.

Unified mass units (u)

400
The lessening of attractive power between the positive nucleus and the negative electrons with increased distance or higher energy shells.

Shielding Effect

400

This force holds together the nucleus of atoms. 

Strong nuclear force

400

The energy wave released through Gamma decay

Photon

500
The measure of how readily an element undergoes a chemical reaction. 

Reactivity

500

The tendency of repeating elemental properties on the periodic table. 

Periodicity

500
The measurement of relative attraction that an atom has for electrons it shares. 

Electronegativity 

500

The difference of mass between an atom and its subatomic particles.

Mass defect

500

A positively charged particle with the same mass as an electron. 

Positron