VOCABULARY SHEET
Vocabulary
Electron
Nucleus
Proton
Neutron
Isotope
Atomic number
Mass number
Atomic mass
Thomson’s model
Rutherford’s model
Bohr’s model
Principle energy
level
Orbital
Aufbau principle
Pauli exclusion
principle
Hund’s rule
Electron
configuration
Ground state
Exited state
Valence electron
Electron shielding
Ionization energy
Atomic radius
Ionic radius
Electronegativity
Definition
An electron is a negatively charged component of an atom. Electrons
exist outside of and surrounding the atom nucleus. Each electron carries
one unit of negative charge and has a very small mass as compared with
that of a neutron or proton
Nucleus means center and it’s a very tiny, dense region in the center of
an atom. In chemistry, nucleus refers to the positively charged center of
the atom containing protons and neutrons.
A proton is a component of an atomic nucleus with a mass defined as 1
amu and a charge of +1
The neutron is the particle in the atomic nucleus with a mass = 1 amu and
charge = 0.
Isotopes are an atoms with the same number of protons, but differing
numbers of neutrons.
The number of protons in an atom
An integer equal to the sum of the number of protons and neutrons of an
atomic nucleus.
Atomic mass is the average mass of atoms of an element, calculated
using the relative abundance of isotopes in a naturally-occurring element.
His investigation of cathode rays led to the discovery of the electron and
his 'plum pudding' model where the atom is made up of electrons
scattered throughout a cloud of massless positive charge.
His gold foil experiment helped describe the atom as having a central
positive nucleus surrounded by negative orbiting electrons.
It is a modification of the earlier Rutherford Model. It explains the
Rydberg formula for the spectral emission lines of atomic hydrogen.
The main energy level occupied by the electrons
A region in an atom where there is a high probability of finding electrons
Electrons fill orbitals that have the lowest energy first
No more than two electrons can occupy a single orbital
Orbitals at the same sub-level are each occupied by one electron before
any paring occurs
The arrangement of electrons in an atom
The lowest allowed energy state of an atom
It’s a state in which an atom picks up outside energy, causing an electron
to move into a higher-energy orbital.
The electrons in the outermost energy level of an atom
The inner electrons shield the outermost electrons from the full attractive
force of the nucleus
The energy that is supplied to remove an electron
Half the distance between the nuclei of two bonded atoms
The size of an ion, which is formed by either losing or gaining electrons
A numerical value that reflects how much an atom in a molecule attracts
electrons