Pupil sheet · Inside the atom

Inside the atom — final check

Name ______________________ Date ____________

Work alone, with the lesson closed. Answer every question; there are no hints.

1. deduce / explain

The symbol shows an atom of argon. (a) Deduce the numbers of protons, neutrons and electrons in the argon atom. (b) A different particle has 19 protons, 20 neutrons and 18 electrons. State its mass number and its charge, and name the element. (The elements with proton numbers 17 to 20 are chlorine, argon, potassium and calcium.) (c) Both particles have 18 electrons. Explain why they are not the same element.

The symbol Ar with mass number 40 at the top left and proton number 18 at the bottom left.

(a) Protons, neutrons and electrons in the argon atom

(b) Mass number, charge and element of the other particle

2. state / deduce / explain

(a) Write the electronic configurations of nitrogen (proton number 7) and argon (proton number 18). (b) State the Group and the Period of each element and explain how its configuration shows them. (c) Aluminium has proton number 13. Write the electronic configuration of an aluminium ion, Al³⁺.

(a) Configurations of nitrogen and argon

(b) Group and Period of each, and how you know