Answer
a. 1 proton, 1 neutron and 1 electron
b. 7 protons, 7 neutrons and 7 electrons
c. 14 protons, 12 neutrons and 14 electrons
d.30 protons, 40 neutrons and 30 electrons
Work Step by Step
To answer this question you must study topic 4.4 ' Atomic number and Mass number' on page 114 and topic 4.5 ' Isotopes and Atomic Mass' on page 117.
a. the number above the element is the mass (2) and the number below represents the atomic number (1 proton), since the number of electrons is the same as protons, helium has 1 electron. The number of neutrons is given by 'mass number - number of protons' (2-1=1 neutron).
