Atomic Structure Vocabulary

Flashcards for Regents Chemistry Unit 1 Vocabulary

Anion

Negatively charged atom; an atom that gains an electron

Atom

The basic unit of structure for all matter; can’t be broken down any further by chemical means; neutrally charged (have the same number of protons + and electrons -)

Atomic Mass

The average mass of all naturally occurring isotopes for an element

Atomic Mass Unit (a.m.u.)

1/12th the mass of a carbon-12 atom; the mass of one proton or neutron

Atomic Number

The number of protons in an atom of a given element

Bohr Model

Atomic model constructed by Neils Bohr that proposes all electrons can be found in orbitals or paths; electrons must gain or lose energy to jump from one orbital to another

Cation

Positively charged atom; an atom that loses an electron

Electron

Virtually MASSLESS (very tiny!), NEGATIVELY charged (-1) particle found OUTSIDE the nucleus

Electron Configuration

The arrangement of electrons in an atom or molecule

Element

Particles that all have the same number of protons in the nucleus

Excited State

When an atom absorbs energy and one or more of its electrons “jump” to an orbital further from the nucleus

Ground State

When all electrons within an atom fill the lowest energy orbitals; when the electrons are where they would “normally” be

Ion

A charged atom; an atom that gains or loses an electron

Isotope

An atom of an element with the same number of protons (atomic #) but a different number of neutrons

Mass Number

The mass of a given isotope of an element; the sum of the masses of protons and neutrons

Neutron

Subatomic particle with a MASS of 1 amu (atomic mass unit), and a CHARGE of zero found WITHIN THE NUCLEUS; NEUTRAL

Nuclear Charge

Electric charge within the nucleus of an atom; equal to the # of protons (always positive!)