Question

review

1. list the charge, location, and mass of a proton, a neutron, and an electron.
2. determine the number of protons, neutrons, and electrons in an atom of aluminum-27.
3. doing calculations the metal thallium occurs naturally as 30 percent thallium-203 and 70 percent thallium-205. calculate the atomic mass of thallium.

Explanation:

Question 1

This question is about the properties of subatomic particles (proton, neutron, electron) which falls under Chemistry (a subfield of Natural Science).

• Proton: Charge is $+1$ (or $+1e$, where $e$ is elementary charge), located in the nucleus, mass is approximately $1.6726\times10^{-27}\ \text{kg}$ (or $1\ \text{amu}$).
• Neutron: Charge is $0$, located in the nucleus, mass is approximately $1.6749\times10^{-27}\ \text{kg}$ (or $\approx1\ \text{amu}$).
• Electron: Charge is $-1$ (or $-1e$), located in electron cloud (outside nucleus), mass is approximately $9.1094\times10^{-31}\ \text{kg}$ (or $\approx\frac{1}{1836}\ \text{amu}$).

Aluminum has an atomic number (Z) of 13 (from periodic table). For a neutral atom:

• Protons: Atomic number = number of protons, so 13.
• Electrons: In neutral atom, electrons = protons, so 13.
• Neutrons: Mass number (A) = 27 (from aluminum - 27). Neutrons = A - Z = $27 - 13 = 14$.

Step 1: Recall atomic mass formula

Atomic mass = (fraction of isotope 1 × mass of isotope 1) + (fraction of isotope 2 × mass of isotope 2)

Step 2: Identify values

• Fraction of thallium - 203: $0.30$ (30%), mass = $203\ \text{amu}$
• Fraction of thallium - 205: $0.70$ (70%), mass = $205\ \text{amu}$

Step 3: Calculate contribution of each isotope

• Contribution of Tl - 203: $0.30\times203 = 60.9$
• Contribution of Tl - 205: $0.70\times205 = 143.5$

Step 4: Sum contributions

Atomic mass = $60.9 + 143.5 = 204.4$

Answer:

• Proton: Charge = $+1$, Location = Nucleus, Mass ≈ $1.6726\times10^{-27}\ \text{kg}$ (or $1\ \text{amu}$)
• Neutron: Charge = $0$, Location = Nucleus, Mass ≈ $1.6749\times10^{-27}\ \text{kg}$ (or $\approx1\ \text{amu}$)
• Electron: Charge = $-1$, Location = Electron cloud, Mass ≈ $9.1094\times10^{-31}\ \text{kg}$ (or $\approx\frac{1}{1836}\ \text{amu}$)

Question 2