Unit 3 key terms: Atomic structure, periodic table, and Elements

Group

A set of elements occupying a column in the periodic table and having broadly similar properties arising from their similar electronic structure.

Nucleus

A small positively charged center of an atom, contains protons and neutrons.

Bohr Model

An atom consisting of a small, postively charged nucleus orbited by negatively charged electrons.

Noble Gas

Any of the gaseous elements helium,neon,argon,krypton,xenon, and radon, occupying group 0(18) of the periodic table.

Isotopes

Atoms of the same element that have different numbers of neutrons.

Ion

Charged particle that has either more or fewer electrons than protons.

Neutron

Electrically neural particle inside the nucleus of an atom

Metalloids

Element that shares some properties with metals and some with nonmetals.

Valence Electron

Elements in the same group have the same number of electrons in their outermost levels.

Metals

Elements that are shiny,malleable,ductile, and good conductors of heat and electricity.

Nonmetals

Elements that are usually gases or solids at room temperature.

Period

Horizontal row in the periodic table; the amount of time it takes one wavelength to pass a fixed point; is expressed in seconds.

Superscript

Number on the top right of element symbol that is its mass number.

Subscript

Number that is written below the element that lets you know how many molecules of that element are present.

Proton

Particle in the nucleus with an electric charge of 1+

Electron

Particle with an electric charge of 1-, surrounds the nucleus of an atom.

Fission

Process of splitting an atomic nucleus into two or more nuclei with smaller masses, releasing large amounts of energy.

Fusion

Reaction in which two or more atomic nuclei form a nucleus with a larger mass, releasing large amounts of energy.

Atom

Smallest particle of an element that retains the element's properties.

Mass number

Sum of the number of protons and the number of neutrons in the nucleus of an atom.

Atomic Mass

The mass of an atom of a chemical element expressed in atomic mass units. (Equivalent to the # of the protons and neutrons in the atom)

Atomic Number

The number of protons in an atom's nucleus.