The atomic number tells you the number of protons.
The mass number is the total number of protons + neutrons.
In this notation, the mass number goes at the top left and the atomic number at the bottom left.
Protons = atomic number
Neutrons = mass number − atomic number
Electrons in a neutral atom = protons
Atomic number = 11. Mass number = 23.
Check: 11 protons + 12 neutrons = mass number 23.
Atomic number: protons.
Mass number: protons + neutrons.
Neutral atom: protons = electrons.
Read the numbers. Count the particles.
Mass number at the top; atomic number below.
One point for each answer you get right first time.
No timer. Take your time and use a clue whenever you need one.