Question

Draw a simple Bohr model (no subshells) for an oxygen atom. How many electrons are in the valence shell? How many more electrons can be put into the valence shell?

Short answer

The simple Bohr model of an oxygen atom consists of a nucleus with the symbol 'O', and two electron shells. The first shell (n=1) has 2 electrons, while the second shell (n=2) has 6 electrons. Oxygen has 6 valence electrons (in the outermost shell) and can accommodate 2 more electrons in its valence shell.

Step-by-step solution

Identify Oxygen's atomic number and electron configuration

Oxygen has an atomic number of 8, which means it has 8 electrons. The electron configuration for a neutral oxygen atom in a simple Bohr model is 2-6, where the first shell has 2 electrons, and the second shell has 6 electrons.

Draw the simple Bohr model

To draw the simple Bohr model of an oxygen atom, follow these steps: 1. Draw a small circle in the center of your paper. This represents the nucleus, which contains the protons and neutrons. 2. Write the symbol 'O' for oxygen inside the nucleus. 3. Draw the first energy level/shell (n=1) as a circle around the nucleus. 4. Place two electrons (represented as small dots or crosses) on the first energy level/shell (n=1) to represent the two electrons that occupy this shell. 5. Draw the second energy level/shell (n=2) as a larger circle around the first shell. 6. Place six electrons (represented as small dots or crosses) on the second energy level/shell (n=2), distributed evenly to represent the six electrons that occupy this shell. Now you have a simple Bohr model of an oxygen atom.

Determine the valence electrons

Valence electrons are the electrons in the outermost shell of an atom. In the simple Bohr model we drew, the outermost shell is the second shell (n=2), which contains 6 electrons. Therefore, oxygen has 6 valence electrons.

Calculate available spots for additional electrons

To find how many more electrons can be put into the valence shell, we need to subtract the current number of valence electrons (6) from the maximum capacity of the shell. The second shell (n=2) can hold a maximum of 2(2^2) = 8 electrons. Therefore, oxygen's valence shell can accommodate 8 - 6 = 2 more electrons.

Key concepts

Atomic Number

Understanding the atomic number is crucial when studying atoms and elements. The atomic number is what defines an element and its position on the periodic table. For instance, oxygen has an atomic number of 8. This tells us that a neutral oxygen atom possesses 8 protons in its nucleus. Furthermore, because atoms are electrically neutral, the number of protons (positive charges) is equal to the number of electrons (negative charges).As such, an oxygen atom also contains 8 electrons. These electrons are arranged in distinct orbits or energy levels around the nucleus. Knowing the atomic number allows one to determine the electron configuration of an element, which is critical in predicting how it will interact with other atoms.

Electron Configuration

The electron configuration of an atom describes how electrons are distributed in its energy levels and subshells. Referring to the oxygen atom, with its atomic number of 8, its electrons are placed according to certain rules. In a simplified Bohr model, the first energy level can hold up to 2 electrons, and subsequent levels can hold more according to the formula 2n^2.

In the case of oxygen, the electron configuration is expressed as 2-6, meaning there are two electrons in the first energy level and six in the second. It's important to note that this simplification does not take into account electron subshells, which are considered in the more comprehensive quantum mechanical model of the atom.

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom. These are the electrons that are involved in forming chemical bonds, as they are the most loosely held and free to interact with other atoms. The number of valence electrons plays a key role in determining an element's chemical properties and reactivity.

For oxygen, the valence electrons can be determined based on its electron configuration (2-6). The six electrons in the second energy level are the valence electrons for an oxygen atom. This means that in chemical reactions, oxygen tends to gain or share two electrons to achieve a full valence shell, which would mimic the stable electronic configuration of neon, the next noble gas in the periodic table.

Energy Levels

Energy levels, sometimes called electron shells, are fixed distances from the nucleus of an atom where electrons are likely to be found. According to the Bohr model, an atom has several energy levels that can each hold a certain number of electrons. The first level holds a maximum of 2 electrons, while the second level can carry up to 8, following 2n^2 rule where n is the level number.

For oxygen, with its electron configuration of 2-6, its electrons completely fill the first energy level and partially fill the second. The fact that the second energy level is not filled means that oxygen can hold more electrons. In fact, it can accommodate 2 more, as it only holds 6 of the possible 8 electrons at that level. This is crucial for understanding oxygen's tendency to form compounds by gaining or sharing electrons to fill its valence shell.