6 2.1 Atoms: The Building Blocks of Everything

Practice questions

Multiple choice questions (There is/ are one or more correct answer(s) for each question).

1. Which of the following are statements of modern atomic theory?
   1. All matter is composed of atoms.
   2. All matter consists of energy.
   3. Atoms of the same element are the same; atoms of different elements are different.
   4. Atoms combine in whole-number ratios to form compounds.
   5. Energy and matter can be transformed into one another.
2. Which subatomic particle is larger?
   1. A proton
   2. An electron
3. Which subatomic particle is larger?
   1. A neutron
   2. An electron
4. Where is most of the mass of an atom located?
   1. Protons
   2. Electrons
   3. Neutron
   4. Nucleus

Short-answer questions

1. What are the charges for each of the three subatomic particles?
   1. Protons
   2. Electrons
   3. Neutrons
2. Calculate the number of protons, electrons and neutrons present in the atom Argon, whose atomic number is 18 and the mass number is 40.
3. The atomic number of Lithium is 3, and its mass number is 7. Calculate the total number of nucleons present in the atom.

Solutions

Multiple choice questions (There are one or more correct answer(s) for each question)

1. a, c, d
2. a
3. a
4. d

Short-answer questions

1. 1. Protons – Positive
   2. Neutrons – no charge
   3. Electrons – Negative
2. 1. Number of protons=Atomic number Z=Number of electrons =18
   2. Number of neutrons = Mass number − Number of protons
   3. Number of neutrons = 40 − 18
   4. Number of neutrons = 22
3. 1. Protons and neutrons are nucleons.
   2. Total number of nucleons = Number of protons + Number of neutrons
   3. Mass number = Number of protons + Number of neutrons
   4. Therefore, the total number of nucleons is equal to the Mass number, which is 7.