What is the next atomic orbital in the series below? 1s, 2s, 2p, 3s, 3p, 4s, a. 3d b. 4d c. 4p d. 5s

3d is the correct option

A) 3d

Explanation:

To know how to fill atomic orbitals, you have to use the Aufbau Principle. Aufbau Principle, which is also called Building-up Principle, states that electrons fill orbitals in order of increasing energy.

Madelung´s Rule also helps us to determine the energy level of each orbital and besides, the order to filling them. It claims that:

The energy of an atomic orbital increases with the n+l value. For identicals values of n+l, energy increases with increasing n.

The first number of each orbital is n, the principal quantum number. Then l takes values of 0, 1, 2 and 3, according to the orbital letter:

l=0 for s orbitalsl=1 for p orbitalsl=2 for d orbitalsl=3 for f orbitals

Let´s calculate n+l values in this exercise:

1s > n=1 and l=0, so n+l=12s > n=2 and l=0, so n+l=22p > n=2 and l=1, so n+l=33s > n=3 and l=0, so n+l=33p > n=3 and l=1, so n+l=4

As 2p and 3s have both n+l=3, we use the second statement of Madelung´s Rule to determine the orbital which fills first (that with lower energy), and so, 2p fills before 3s as it has lower n value.

Now, let´s calculate n+l values for the possible answers:

A) 3d > n=3 and l=2, so n+l=5B) 4d > n=4 and l=2, so n+l=6C) 4p > n=4 and l=1, so n+l=5D) 5s > n=5 and l=0, so n+l=5

Answer B) isn´t correct because 4d is the orbital with the highest n+l value, so the highest energy level and the last orbital in the answers that must be filled.

For answers A), C) and D), as they have identical n+l values, it´s necessary to use the second statement of Madelung´s Rule again. Increasing in n shows the order of increasing energy and the correct order of filling orbitals. So, 3d orbital (answer A) must be filled first than 4p and 5s, as well; and of course, as we said before, 3d orbital must be also filled before 4d.

The correct answer is A) 3d.

1. and 2. question: in which equation? or i don't understand you, 3. a), 4. c), 5. c), 6. b), 7. d), 8. d) if small number is underlined(behind symbol) , b) if big number is underlined(in front of symbol)9. what is underlined there? 10. c)

False, as a substance changes from a solid to a liquid and from a liquid to a gas the molecules get farther apart from each other