Question

The incorrect statement among the following is (1) The mass of one mole of electron is \(0.55 \mathrm{mg}\). (2) Positive charge in an atom is concentrated in the nucleus. (3) Combination of a \(\alpha\) -particle with a nuclide results in the formation of a new nuclide that has higher atomic number. (4) Atoms of all elements should contain equal number of protons and neutrons.

Short answer

Statement (4) is incorrect.

Step-by-step solution

Review each statement

Start by analyzing each statement: (1) The mass of one mole of electron is \(0.55 \mathrm{mg}\). (2) Positive charge in an atom is concentrated in the nucleus. (3) Combination of an \(\alpha\)-particle with a nuclide results in the formation of a new nuclide that has higher atomic number. (4) Atoms of all elements should contain equal number of protons and neutrons.

Check the mass of one mole of electrons

Recall that the mass of one electron is approximately \(9.11 \times 10^{-31}\) kg. Therefore, the mass of one mole (Avogadro’s number, \(6.022 \times 10^{23}\)) of electrons is: \[(9.11 \times 10^{-31} \text{kg}) (6.022 \times 10^{23}) \approx 5.48 \times 10^{-7} \text{kg} \approx 0.55 \text{mg}\] Thus, statement (1) is correct.

Verify the positive charge in an atom

Positive charge in an atom is found in the nucleus, which contains protons and neutrons. Statement (2) is correct.

Analyze the combination of an \(\alpha\)-particle with a nuclide

\(\alpha\)-particles have 2 protons and 2 neutrons. When combined with a nuclide, the atomic number (number of protons) of the new nuclide indeed increases by 2. Statement (3) is correct.

Evaluate the composition of atoms

Not all elements have equal numbers of protons and neutrons. For example, the common isotope of hydrogen has 1 proton and no neutron. Thus, statement (4) is incorrect.

Key concepts

Mole Concept

The mole concept is an essential principle in chemistry that helps us understand the amount of substance. One mole of any substance contains exactly Avogadro’s number of particles, which is approximately \( 6.022 \times 10^{23} \) particles. This can be atoms, molecules, or ions. The mass of one mole of electrons, calculated from the mass of a single electron (\( 9.11 \times 10^{-31} \) kg), equates to approximately 0.55 mg. Understanding the mole concept is crucial as it allows chemists to quantify substances on a macroscopic scale based on microscopic properties.

Alpha Particles

Alpha particles are subatomic particles consisting of 2 protons and 2 neutrons. They are emitted during radioactive decay processes. When an \( \alpha \)-particle combines with another nuclide, the resulting new nuclide has an increased atomic number by two and mass number by four. This is because the \( \alpha \)-particle essentially adds two protons and two neutrons to the nuclide. This concept is fundamental in nuclear chemistry and plays a significant role in understanding nuclear reactions and stability.

Protons and Neutrons

Protons and neutrons are subatomic particles found in the nucleus of an atom. Protons carry a positive charge, while neutrons have no charge. The number of protons in the nucleus determines the element's identity and is known as the atomic number. Neutrons contribute to the mass of the atom but do not affect its chemical properties.
It's important to note that different elements and even different isotopes of the same element do not necessarily have an equal number of protons and neutrons. For instance, the most common isotope of hydrogen (protium) has 1 proton and no neutrons, whereas deuterium, another hydrogen isotope, has 1 proton and 1 neutron. This discrepancy in proton and neutron count profoundly affects the properties and stability of the atoms.