Atom to the positively charged nucleus by the attraction created from opposite electric charges. If an atom has more or fewer electrons than its atomic number, then it becomes respectively negatively or positively charged as a whole; a charged atom is called an ion. Electrons have been known since the late 19th century, mostly thanks to J.J. Thomson; see history of subatomic physics for details. Protons have a positive charge and a mass 1,836 times that of the electron, at . The number of protons in an atom is called its atomic number. Ernest Rutherford (1919) observed that nitrogen under alpha-particle
Atom (time) Atom (time) An Atom of time or "a-tom" (“indivisible” in Greek), refers to the smallest possible unit of time. One of the earliest occurrences of the word “atom” to mean the smallest possible unit of measuring time is found in the Greek text of the New Testament in Paul's . The text compares the length of time of the “atom” to the time needed for “the twinkling of an eye.” The text reads: “en atomo, en repe ophthamou” – the word "atom" is usually translated "a moment" - “In a moment, in the twinkling of an eye”. With that meaning