In 1911, Ernest Rutherford gave a model of the atom in which a central nucleus held most of the atom's mass and a positive charge which, in units of the electron's charge, was to be approximately equal to half of the atom's atomic weight, expressed in numbers of hydrogen atoms.
ɪn nˈaɪntiːnhˈʌndɹɪd ɪlˈɛvən, ˈɜːnɪst ɹˈʌðɚfɚd ɡˈeɪv ɐ mˈɑːdəl ʌvðɪ ˈæɾəm ɪnwˌɪtʃ ɐ sˈɛntɹəl nˈuːklɪəs hˈɛld mˈoʊst əv ðɪ ˈæɾəmz mˈæs ænd ɐ pˈɑːzᵻtˌɪv tʃˈɑːɹdʒ wˈɪtʃ, ɪn jˈuːnɪts ʌvðɪ ᵻlˈɛktɹɑːnz tʃˈɑːɹdʒ, wʌz təbi ɐpɹˈɑːksɪmətli ˈiːkwəl tə hˈæf ʌvðɪ ˈæɾəmz ɐtˈɑːmɪk wˈeɪt, ɛkspɹˈɛst ɪn nˈʌmbɚz ʌv hˈaɪdɹədʒən ˈæɾəmz.