Applying the Bohr Theory, which of the following represents the electron composition of the main energy levels (MEL) for aluminum? (Main energy level is equivalent in terminology to main shell.) MEL 1 – 2 electrons; MEL 2 – 8 electrons; Mel 3 – 8 electrons MEL 1 – 2 electrons; MEL 2 – 8 electrons; Mel 3 – 13 electrons MEL 1 – 2 electrons; MEL 2 – 8 electrons; Mel 3 – 3 electrons 2 points QUESTION 2 The ancient Greek philosophers were most likely the first to study the behavior of matter in an organized way. What is the major distinction between the study of matter by “Greek philosophers” and the “modern scientific study of matter?” Observation Experimentation Hypotheses Logic 2 points QUESTION 3 The known density of a specific type of steel is 8.10 g/cm3. What is the mass of a 1.26 L volume of this type of steel? 10.206 g 102.06 g None of these 10,206 g
The Correct Answer and Explanation is:
Question 1:
Correct Answer:
MEL 1 – 2 electrons; MEL 2 – 8 electrons; MEL 3 – 3 electrons
Question 2:
Correct Answer:
Experimentation
Question 3:
Correct Answer:
10,206 g
Explanation:
Question 1: Bohr Theory and Aluminum’s Electron Configuration
Bohr’s model of the atom describes electrons as occupying fixed energy levels (also called main energy levels or shells) around the nucleus. These levels are labeled as MEL 1 (K), MEL 2 (L), MEL 3 (M), and so on. Each level has a maximum number of electrons it can hold: MEL 1 can hold up to 2, MEL 2 up to 8, and MEL 3 up to 18, but elements fill these levels based on energy stability and electron configuration rules.
Aluminum (Al) has an atomic number of 13, meaning it has 13 electrons. According to Bohr’s theory and the Aufbau principle:
- MEL 1 holds 2 electrons,
- MEL 2 holds 8 electrons,
- MEL 3 holds the remaining 3 electrons.
So, the electron configuration across main energy levels is:
2, 8, 3.
Question 2: Greek Philosophers vs. Modern Scientists
Ancient Greek philosophers such as Democritus and Aristotle were among the first to contemplate the nature of matter. However, their approach was primarily based on logic and reasoning without conducting actual experiments. In contrast, modern science relies on a structured process called the scientific method, which includes observation, forming hypotheses, and most importantly, experimentation to test those hypotheses.
This major distinction—the use of experimentation—is what separates modern scientific study from ancient philosophical speculation.
Question 3: Mass from Density and Volume
To calculate mass from density and volume, use the formula:Mass=Density×Volume\text{Mass} = \text{Density} \times \text{Volume}Mass=Density×Volume
Given:
- Density = 8.10 g/cm³
- Volume = 1.26 L = 1260 cm³ (since 1 L = 1000 cm³)
Mass=8.10 g/cm3×1260 cm3=10,206 g\text{Mass} = 8.10 \, \text{g/cm}^3 \times 1260 \, \text{cm}^3 = 10,206 \, \text{g}Mass=8.10g/cm3×1260cm3=10,206g
So the correct mass is 10,206 grams.
