Question

If a species has 11 protons, 12 neutrons and 10 electrons then

1. what is its atomic number and mass number? 
2. is it neutral, a cation or an anion? Explain. 
3. write its electronic configuration. 
4. name the species.

Answer 1

1. Atomic number = 11 (number of protons); mass number = $$11 + 12 = 23$$.
2. It is a cation because it has 11 protons but only 10 electrons, giving it a net charge of +1.
3. Electronic configuration of the ion: $$2, 8$$.
4. The species is the sodium ion, $$\mathrm{Na}^{+}$$ (sodium-23 cation).