Atom

atom

smallest particle of a chemical e

Particles within the Nucleus | Proton

positively charged subatomic particle forming part of the nucleus of an atom and determining the atomic number of an element

Particles within the Nucleus | Neutron

subatomic particle found in the nucleus of atoms that differs from the other subatomic particles in the nucleus of atoms because neutrons have no charge

electron

stable particle, negative charge

allotrope

elements that exists in two or more different forms in the same physical state

• have different chemical and physical properties due to the different ways in which the atoms bond together to create each allotrope

isotope

same element with same number of protons, different numbers of neutrons

isobars

same mass number, different atomic number

atomic number

number of protons in the nucleus

mass number

protons + neutrons

ion

carries an electric charge

anion

number of electrons > number of protons

cation

number of protons > number of electrons

covalent radius

radius of an atom when covalently bonded to other atoms

metallic radius

½ of the distance between nuclei of two atoms in crystal or between two adjacent metal ions in the metallic lattice

ionization energy

energy needed to remove an electron from an atom or molecule to infinity

electron affinity

energy given off when a neutral atom in the gas phase gains an extra electron to form a negatively charged ion

electronegativity

tendency of an atom or a functional group to attract electrons towards itself

• increases from left to right