helium (He)
The element with a mass of less than 30 and is a noble gas is Neon (Ne). Neon has an atomic mass of around 20.18 and is a colorless, odorless gas commonly used in neon signs due to its bright red-orange glow when electrified.
Atomic mass increases from top to bottom and left to right on the periodic table. In each row, the noble gasses have the highest atomic mass. As you travel down that column, also called a group or family, the noble gasses increase in atomic mass. The naturally occurring noble gas with the highest atomic mass is Radon (Rn; atomic mass = 211.4 amu). In 2002, the unstable element Ununoctium was synthesized, and although it is a member of group 18, it was later determined to be a solid at room temperature, so it is not classified as a noble gas.
The element with a mass of 30 and is a noble gas, other than neon, is krypton (Kr). With an atomic number of 36, krypton has 36 protons in its nucleus and typically has 44 neutrons in its most common isotope, giving it an atomic mass near 84.
Atomic number is the number of protons. Atomic mass is (mostly) the sum of the masses of the protons and neutrons (more or less).
Magnesium is a meta element. Atomic mass of it is 24.
Radon
The element with a mass of less than 30 and is a noble gas is Neon (Ne). Neon has an atomic mass of around 20.18 and is a colorless, odorless gas commonly used in neon signs due to its bright red-orange glow when electrified.
Element 34, Selenium, has an atomic mass of about 78.96.
No element can have those features; the mass can never be less than the atomic number in any element.
Atomic mass increases from top to bottom and left to right on the periodic table. In each row, the noble gasses have the highest atomic mass. As you travel down that column, also called a group or family, the noble gasses increase in atomic mass. The naturally occurring noble gas with the highest atomic mass is Radon (Rn; atomic mass = 211.4 amu). In 2002, the unstable element Ununoctium was synthesized, and although it is a member of group 18, it was later determined to be a solid at room temperature, so it is not classified as a noble gas.
The noble gas with 48 neutrons and a mass of less than 100 is Krypton. It has an atomic number of 36, which means it has 36 protons in its nucleus. The total mass of Krypton is slightly less than 100 atomic mass units.
The element with a mass of 30 and is a noble gas, other than neon, is krypton (Kr). With an atomic number of 36, krypton has 36 protons in its nucleus and typically has 44 neutrons in its most common isotope, giving it an atomic mass near 84.
Atomic number is the number of protons. Atomic mass is (mostly) the sum of the masses of the protons and neutrons (more or less).
Magnesium is a meta element. Atomic mass of it is 24.
The element is Iodine (I). It has an atomic mass of about 126.9.
The element with the highest atomic mass is Oganesson.
Element A has a greater atomic mass than element B if the atomic mass value of A is higher. The atomic mass represents the average mass of an element’s isotopes based on their abundance in nature.