Question

section 5.2 continued
in your textbook, read about the heisenberg uncertainty principle.
for each item in column a, write the letter of the matching item in column b.
column a

1. the modern model of the atom that treats electrons as waves
2. states that it is impossible to know both the velocity and the position of a particle at the same time
3. a three - dimensional region around the nucleus representing the probability of finding an electron
4. originally applied to the hydrogen atom, it led to the quantum mechanical model of the atom

answer the following question.

1. how do the bohr model and the quantum mechanical model of the atom differ in how they describe electrons?

in your textbook, read about hydrogens atomic orbitals.
in the space at the left, write the term in parentheses that correctly completes the statement.

1. atomic orbitals (do, do not) have an exactly defined size.
2. each orbital may contain at most (two, four) electrons.
3. all s orbitals are (spherically shaped, dumbbell shaped).
4. a principal energy has (n, n²) energy sublevels.
5. the maximum number of (electrons, orbitals) related to each principal energy level equals 2n².
6. there are (three, five) equal energy p orbitals.
7. hydrogens principal energy level 2 consists of (2s and 3s, 2s and 2p) orbitals.
8. hydrogens principal energy level 3 consists of (nine, three) orbitals.

column b
a. heisenberg uncertainty principle
b. schrödinger wave equation
c. quantum mechanical model of the atom
d. atomic orbital

Explanation:

1. The quantum - mechanical model of the atom treats electrons as waves.
2. The Heisenberg uncertainty principle states that it is impossible to know both the velocity and the position of a particle at the same time.
3. An atomic orbital is a three - dimensional region around the nucleus representing the probability of finding an electron.
4. The Schrödinger wave equation, originally applied to the hydrogen atom, led to the quantum mechanical model of the atom.
5. The Bohr model describes electrons as moving in fixed orbits around the nucleus, while the quantum mechanical model describes electrons as existing in probability clouds (orbitals) around the nucleus.
6. Atomic orbitals do not have an exactly defined size as the probability of finding an electron extends to infinity, though the probability is very low at large distances.
7. Each orbital may contain at most two electrons according to the Pauli exclusion principle.
8. All s orbitals are spherically shaped.
9. A principal energy level has $n^{2}$ energy sublevels.
10. The maximum number of electrons related to each principal energy level equals $2n^{2}$.
11. There are three equal - energy p orbitals.
12. Hydrogen's principal energy level 2 consists of 2s and 2p orbitals.
13. Hydrogen's principal energy level 3 consists of nine orbitals ($n^{2}=3^{2} = 9$).

Answer:

1. c. quantum mechanical model of the atom
2. a. Heisenberg uncertainty principle
3. d. atomic orbital
4. b. Schrödinger wave equation
5. The Bohr model describes electrons in fixed orbits; the quantum - mechanical model describes electrons in probability clouds (orbitals).
6. do not
7. two
8. spherically shaped
9. $n^{2}$
10. electrons
11. three
12. 2s and 2p
13. nine