Atomic Models & Subatomic Particles — Drills · Grade 11 Science

What these drills covers

By the end of Atomic Models & Subatomic Particles you should be able to:

I can trace how the model of the atom changed from Dalton through Thomson, Rutherford, Bohr, and the quantum-mechanical picture, and explain what experiment forced each revision.
I can state the charge, relative mass, and location of protons, neutrons, and electrons.
I can use atomic number and mass number (including isotope notation) to find the numbers of protons, neutrons, and electrons in an atom or ion.

6 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: atom, proton, neutron, electron, nucleus, atomic number (Z), mass number (A), ion, atomic mass unit (amu).

Problem 1

Which scientist proposed the 'plum-pudding' model, with electrons scattered through a ball of positive charge?

John Dalton
J.J. Thomson
Ernest Rutherford
Niels Bohr

Answer and explanation

J.J. Thomson

Thomson discovered the electron and proposed the plum-pudding model; Rutherford later replaced it with the nuclear atom.

Problem 2

A nitrogen atom has atomic number 7 and mass number 14. How many neutrons does it have?

Answer and explanation

Neutrons = A − Z = 14 − 7 = 7.

Problem 3

A neutral arsenic atom has atomic number 33 and mass number 75. How many neutrons does it have?

Answer and explanation

Neutrons = A − Z = 75 − 33 = 42.

Problem 4

Which quantity determines the identity of an element?

the size of the nucleus
the number of neutrons
the number of protons
the number of electrons

Answer and explanation

the number of protons

The proton count (atomic number) fixes the element; changing it changes the element entirely.

Problem 5

Put these models in order and name the discovery that drove each revision: Dalton, Thomson, Rutherford.

Answer and explanation

Dalton's solid-sphere atom came first. Thomson's discovery of the electron showed atoms have internal parts, giving the plum-pudding model. Rutherford's gold-foil experiment then showed a tiny dense nucleus, replacing the pudding with the nuclear atom.

Problem 6

An oxide ion, O with a 2− charge, has 8 protons and 8 neutrons. How many electrons does it have?

Answer and explanation

A 2− ion has gained 2 electrons: electrons = protons + 2 = 8 + 2 = 10.

Browse all courses