Atomic mass

The atomic mass (m_a) is the mass of an atomic particle, sub-atomic particle, or molecule. It is commonly expressed in unified atomic mass units (u) where by international agreement, 1 unified atomic mass unit is defined as 1/12 of the mass of a single carbon-12 atom (at rest). For atoms, the protons and neutrons of the nucleus account for almost all of the mass, and the atomic mass measured in u has nearly the same value as the mass number.

When divided by unified atomic mass units or daltons to form a pure number ratio, the atomic mass of an atom becomes a dimensionless number called the relative isotopic mass (see section below). Thus, the atomic mass of a carbon-12 atom is 12 u or 12 daltons (Da), but the relative isotopic mass of a carbon-12 atom is simply 12.

Atomic Mass (band)

Atomic Mass was an English hard rock/heavy metal band from Sheffield, who formed in 1977 as part of the New Wave of British Heavy Metal movement. The group's core members along with newly recruited singer Joe Elliott later became Def Leppard, eventually becoming one of the UK's top-selling hard rock bands.

History

Formation

Rick Savage, Nick Mackley, Tony Kenning, and Pete Doubleday, all students in the same year at Tapton School in Sheffield, formed Atomic Mass in 1977. Pete Willis, a year ahead of the members of the band at Tapton and who played guitar, heard of the band and asked to audition. He brought along a friend of his, Paul Hampshire, who also played the guitar. They performed a few songs with Rick and Tony and earned their places in the band, Pete replacing Doubleday, who had been on holiday in France at the time. Paul Holland briefly replaced Mackley, who had departed shortly after Doubleday was replaced. During this time, Atomic Mass played their only public show in Tapton's gymnasium. Their setlist included songs such as Led Zeppelin's Whole Lotta Love and The Who's Boris The Spider. Holland and Nicholas were soon gone and the band found itself without a singer or bass player. Following a chance meeting with Willis after missing a bus, 18-year-old Joe Elliott, who had been in attendance at Atomic Mass's show at Tapton, auditioned for the band as a guitarist. During his audition, however, it was decided that he was better suited to be lead vocalist. Rick Savage also switched to bass as it was deemed that Pete Willis was a more solid guitarist.