Question

Write the electron configuration for each of the following atoms. (Chapter 5) a. fluorine c. titanium b. aluminum d. radon

Short answer

a. Fluorine (F): F = \(1s^2 2s^2 2p^5\) b. Aluminum (Al): Al = \(1s^2 2s^2 2p^6 3s^2 3p^1\) c. Titanium (Ti): Ti = \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^2\) d. Radon (Rn): Rn = \(1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6 6s^2 4f^14 5d^10 6p^6\)

Step-by-step solution

1. Fluorine (F)

Fluorine has an atomic number of 9, so it has 9 electrons. We start filling the orbitals in the order of increasing energy: 1s → 2s → 2p → 3s → 3p → ... For fluorine, we have the electron configuration: F = 1s^2 2s^2 2p^5

2. Aluminum (Al)

Aluminum has an atomic number of 13, so it has 13 electrons. We follow the Aufbau principle to fill the orbitals: Al = 1s^2 2s^2 2p^6 3s^2 3p^1

3. Titanium (Ti)

Titanium has an atomic number of 22, so it has 22 electrons. Continuing to follow the Aufbau principle to fill the orbitals, we get: Ti = 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^2

4. Radon (Rn)

Radon has an atomic number of 86, so it has 86 electrons. Filling the orbitals according to the Aufbau principle, we get the electron configuration: Rn = 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6 6s^2 4f^14 5d^10 6p^6 So, the electron configurations for the given atoms are: a. Fluorine (F): F = 1s^2 2s^2 2p^5 b. Aluminum (Al): Al = 1s^2 2s^2 2p^6 3s^2 3p^1 c. Titanium (Ti): Ti = 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^2 d. Radon (Rn): Rn = 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6 6s^2 4f^14 5d^10 6p^6

Key concepts

Aufbau Principle

Imagine building a house from the ground up; in chemistry, the Aufbau principle works similarly for filling electrons in an atom's orbitals. According to this principle, electrons occupy orbitals starting from the lowest energy level and move to higher levels systematically.

The word 'Aufbau' is German for 'building up,' and it helps us predict the electron configurations of atoms. Since electrons are negatively charged, they want to stay as close as possible to the positively charged nucleus, which means they fill up the 'rooms' or orbitals that require the least energy first before moving on to those that need more energy.

The order in which these orbitals are filled is crucial and can be predicted using a specific sequence or an 'address' known as the orbital filling order. But just as you wouldn't skip laying the foundation of a house to start with the roof, electrons don't jump to higher energy orbitals before the lower ones are filled. This approach keeps the atom in its most stable, energetically favorable state.

Atomic Number

When it comes to understanding where an element stands in the periodic table and its chemical properties, the atomic number holds the key. The atomic number of an element, often denoted by the letter 'Z,' is the number of protons in the nucleus of an atom.

Every element has a unique atomic number, making it a sort of identifier, much like a personal ID number, distinguishing one element from another. For instance, hydrogen has an atomic number of 1, meaning it has one proton, while carbon has an atomic number of 6, with six protons.

In the context of electron configurations, the atomic number tells us exactly how many electrons an atom has when it is in its neutral state (not ionized). Since atoms are electrically neutral overall, the number of protons (atomic number) is equal to the number of electrons. Therefore, knowing the atomic number is essential for writing out the electron configuration of an atom.

Orbital Filling Order

Now let's delve into the 'address book' of where electrons live within an atom. The orbital filling order is essentially the map that guides electrons to their seats within an atom. This order is often remembered by the mnemonic or the diagram technique called an 'energy level diagram.'

Start by considering the different types of orbitals—s, p, d, and f. The orbitals have different shapes and can hold varying numbers of electrons: 's' can hold 2, 'p' can hold 6, 'd' can hold 10, and 'f' can hold 14. The actual order in which these get filled is not as simple as counting upwards, because the energy levels of these orbitals can overlap.

For example, even though the 4s orbital is part of the fourth level, it gets filled before the 3d orbital because it has lower energy. That's why titanium's electron configuration is written with the 4s orbitals filled before the 3d orbitals. Keeping this map in mind helps to correctly distribute the electrons and know when to 'hop' from one orbital to the next, which is key to writing accurate electron configurations.