To understand this process we must first understand a little bit about the atoms themselves and how they get their names.
Most carbon atoms have six positively charged protons and six uncharged neutrons.
This is calculated through careful measurement of the residual activity (per gram C) remaining in a sample whose age is Unknown, compared with the activity present in Modern and Background samples. Thus 1950, is year 0 BP by convention in radiocarbon dating and is deemed to be the 'present'.
You can get an idea of the relationship between C14 and age at the Carbon Dating calculator page. 1950 was chosen for no particular reason other than to honour the publication of the first radiocarbon dates calculated in December 1949 (Taylor, 19).
This tendency to decay, called radioactivity, is what gives radiocarbon the name radiocarbon.
However, cosmic radiation constantly collides with atoms in the upper atmosphere.Part of the result of these collisions is the production of radiocarbon (C, pronounced "c fourteen"), carbon atoms which are chemically the same as stable carbon, but have two extra neutrons.Radiocarbon is not stable; over time radiocarbon atoms decay into nitrogen atoms. Ninety-five percent of the activity of Oxalic Acid from the year 1950 is equal to the measured activity of the absolute radiocarbon standard which is 1890 wood. This is the International Radiocarbon Dating Standard.The Oxalic acid standard was made from a crop of 1955 sugar beet. The isotopic ratio of HOx I is -19.3 per mille with respect to (wrt) the PBD standard belemnite (Mann, 1983). T designation SRM 4990 C) was made from a crop of 1977 French beet molasses.