Honors: Atomic Structure

Atom

When the number of protons and electrons are equal

Atom

Basic unit of matter

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Proton

Identifies an element

Proton

Subatomic particle that never changes for a given element

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Electron

A subatomic particle that has a negative charge

Electron

Subatomic particle found in a cloud around the nucleus

Ion

A charged particle that results from a change in the number of electrons in an atom

Cation

A positively charged ion (has more protons than electrons)

Anion

A negatively charged ion (has more electrons than protons)

Nucleus

the center of an atom, which is positively charged, since it contains the protons and neutrons

Isotope

Alternate forms of an element

Isotope

Atoms of the same element that have different numbers of neutrons and therefore different mass numbers from that on the periodic table

Isotope

When the number of protons and electrons are equal, but the mass number is different from that on the periodic table

Atomic Number

Represents the number of protons in a chemical symbol

Mass Number

A whole number, rounded value, determined by adding the number of protons and neutrons

Atomic Mass

The weighted average mass of all the naturally occurring isotopes of an element

Atomic Mass

A full decimal number determined by adding the number of protons and neutrons (it includes all of the decimal places on the periodic table)

Polyatomic ion

An ion made of different elements bonded together

Quark

very small particles of matter that make up protons and neutrons

Ground state

the lowest energy state of electrons in an atom

Excited state

when an atom absorbs energy, its electrons move to a higher energy level (this is a highly unstable state)

Wavelength

The distance from peak of one wave to the peak of the next wave (or the trough of one wave to the trough of the next wave)

Frequency

The number of waves that pass through a given area over a set time

Electron cloud

area around the nucleus of an atom where the atom's electrons are most likely to be found

Valence electrons

Electrons in the outermost energy level of an atom that are involved in chemical reactions

Cation

An ion that is formed when an element loses electrons

Anion

An ion that is formed when an element gains electrons

Electron cloud

This makes up most of the volume of the atom

Ion

When the number of protons does not equal the number of electrons

Valence electrons

the s and p electrons from the highest energy level

Magnetic (m)

the quantum number that shows the spatial orientation of the orbitals around the nucleus

Magnetic (m)

the quantum number that explains that each sublevel consists of orbitals

Magnetic (m)

the quantum number that provides the maximum number of orbitals in each sublevel

Energy Level

a region surrounding the atom where electrons can be found, there are 7 main levels, the lower the number the closer the electrons are to the nucleus

Sublevel

made up of orbitals, there are 4 different sublevels (s, p, d and f) each has its own shape and each holds a different maximum number of electrons in quantum theory

Orbital

makes up the sublevels in quantum theory

Priniciple (n)

the quantum number that indicates the main energy level

Orbital (l)

the quantum number that shows the maximum number of electrons in each sublevel

Orbital (l)

the quantum number that provides the shape of each orbital

Orbital (l)

the quantum number that indicates there are 4 sublevels

Spin (s)

the quantum number that indicates the spin value of an electron

Spin (s)

the quantum number that demonstrates that a single orbital can hold a maximum of 2 electrons, each with an opposite spin

Electron cloud

the general area where electrons are located in the atom today

Nuclear Fission

A nuclear reaction in which a large atomic nucleus splits into smaller atomic nuclei with a simultaneous release of energy.

Nuclear Fusion

A nuclear reaction in which two or more small atomic nuclei fuse to form a larger atomic nucleus with the simultaneous release of energy.

Alpha Decay

A nuclear reaction in which an atom emits an alpha particle (helium nucleus) and transforms into a smaller atomic nucleus.

Alpha Decay

A type of decay that reduces the atomic number by 2 and the mass number by 4, changing the original element present.

Beta Decay

A nuclear reaction in which an atom emits a beta particle creating an atom where a proton becomes a neutron or a neutron becomes a proton.

Beta Decay

A type of decay in which the mass number (protons + neutrons) stays the same but the atomic number (protons) increases or decreases by 1, changing the original element present.

Gamma Decay

A nuclear reaction in which high-energy gamma-ray photons are emitted from an unstable nucleus. The number of protons and neutrons remains the same.

Radioactive Decay

A spontaneous process in which an unstable atomic nucleus loses energy by emitting radiation. Three of the most common types of radioactive decay are alpha, beta and gamma decay.

Half-Life

The length of time required for half of the radioactive atoms in a sample to decay.

Hund's Rule

States that each orbital must contain one electron before pairing occurs.

Aufbau Principle

States an electron occupies the lowest energy orbital that can receive it