Threshold Knowledge revision 1

Atom

The smallest particle of an element that retains its chemical properties.

Dalton's Atomic Theory

A theory that proposed that matter is composed of small particles called atoms, which are indivisible.

Isotope

Atoms of the same element that differ in mass due to differing numbers of neutrons.

Electron

A negatively charged subatomic particle with a very small mass, approximately 1/1833 of a proton.

Nucleus

The small, dense center of an atom containing protons and neutrons.

Proton

A positively charged subatomic particle found in the nucleus of an atom.

Neutron

An uncharged subatomic particle located in the nucleus of an atom.

Atomic Number (Z)

The number of protons in an atom, which defines the element.

Mass Number (A)

The total number of protons and neutrons in an atom.

Charge of an Atom

The difference between the number of protons and electrons; determines if the atom is neutral or an ion.

Chemical Symbol

An abbreviation used to represent elements, typically consisting of one or two letters.

Nuclear Notation

A way to represent isotopes, indicating mass number, element symbol, and sometimes atomic number.

Mass Defect

The difference between the mass of an atom and the total mass of its individual components (protons and neutrons).

Average Atomic Mass

The weighted average mass of an element's isotopes, accounting for their relative abundances.

Coulomb

The unit of electric charge; the charge of one electron is approximately -1.6 × 10^-19 Coulombs.

Atomic Mass Unit (amu)

A unit of mass used to express atomic and molecular weights; defined as one-twelfth the mass of a carbon-12 atom.