WAEC - Chemistry (2014 - No. 9)
An atom W has 17 electrons and 18 neutrons. Which of the following representations of the atom is correct?
1718W
1817W
3517W
3518W
Wyjaśnienie
The superscript is the atomic mass = 35
(The mass number also called atomic mass number or nucleon number, is the total number of protons and neutrons)
The subscript is the atomic or proton number = 17
The number of electrons in a neutral atom is equal to the number of protons.