"The mass number (symbol A, from the German word: Atomgewicht, 'atomic weight')...is the total number of protons and neutrons...in an atomic nucleus."
Defines mass number as the sum of the number of protons and neutrons in an atom's nucleus and distinguishes it from atomic mass.
Atomic Mass: The average mass of an atom, taking into account the different isotopes and their relative abundance.
Isotopes: Different forms of an element with the same atomic number but different mass numbers due to varying numbers of neutrons.
Nucleus: The center of an atom which contains protons and neutrons.
Protons: Positively charged particles found in the nucleus of an atom.
Neutrons: Neutral particles found in the nucleus of an atom.
Electrons: Negatively charged particles that orbit the nucleus in shells.
Atomic Number: The number of protons in an atom's nucleus.
Mass Number: The total number of protons and neutrons in an atom's nucleus.
Atomic Structure: The arrangement of electrons, protons and neutrons in an atom.
Electron Configuration: The arrangement of electrons in an atom's shells.
Ionization Energy: The energy required to remove an electron from an atom.
Radioactivity: The emission of particles or radiation from unstable atomic nuclei.
Nuclear Fission: The splitting of atomic nuclei to create energy.
Nuclear Fusion: The joining of atomic nuclei to create energy.
Half-Life: The time it takes for half of a radioactive substance to decay.
Quantum Mechanics: The branch of physics that studies the behavior of matter and energy at the atomic and subatomic level.
Bohr's Model: The model of the atom that shows electrons orbiting the nucleus in discrete energy levels.
Schrödinger's Equation: The equation that describes the wave-like behavior of electrons and their probability of being in a particular location.
Subatomic Particles: Particles that make up atoms, including protons, neutrons, and electrons.
Nuclear Forces: The strong and weak forces that hold the nucleus together.
"It is approximately equal to the atomic (also known as isotopic) mass of the atom expressed in atomic mass units."
"The mass number A is identical with the baryon number B of the nucleus... The mass number is different for each isotope...and the difference between the mass number and the atomic number Z gives the number of neutrons (N) in the nucleus: N = A − Z."
"The mass number is written either after the element name or as a superscript to the left of an element's symbol."
"For example, the most common isotope of carbon is carbon-12, or 12C, which has 6 protons and 6 neutrons."
"The full isotope symbol would also have the atomic number (Z) as a subscript to the left of the element symbol directly below the mass number: 126C."
"[The mass number is]...the total number of protons and neutrons (together known as nucleons) in an atomic nucleus."
"The mass number (symbol A, from the German word: Atomgewicht, 'atomic weight'), also called atomic mass number or nucleon number..."
"It is approximately equal to the atomic (also known as isotopic) mass of the atom expressed in atomic mass units."
"Since protons and neutrons are both baryons..."
"The difference between the mass number and the atomic number Z gives the number of neutrons (N) in the nucleus: N = A − Z."
"The mass number is different for each isotope of a given chemical element..."
"The mass number A is identical with the baryon number B of the nucleus (and also of the whole atom or ion)."
"The mass number is written either after the element name or as a superscript..."
"The full isotope symbol would also have the atomic number (Z) as a subscript to the left of the element symbol directly below the mass number..."
"The most common isotope of carbon is carbon-12, or 12C, which has 6 protons and 6 neutrons."
"The mass number is different for each isotope of a given chemical element..."
"The full isotope symbol would also have the atomic number (Z) as a subscript to the left of the element symbol directly below the mass number: 126C."
"The difference between the mass number and the atomic number Z gives the number of neutrons (N) in the nucleus: N = A − Z."
"The mass number is different for each isotope of a given chemical element..."