Chapter 2 Homework Answer Key
All odd-numbered exercises are in the back of the textbook.
2.10 In order for the atom to be electrically neutral, the number of electrons must equal the number of protons. Therefore this atom has 16 protons. The atomic number is defined as the number of protons, so this atom must have an atomic number of 16. Thus it is sulfur.
2.12
|
Protons |
Neutrons |
Electrons |
Mass (amu) |
Element |
|
19 |
20 |
19 |
39 |
K |
|
34 |
45 |
34 |
79 |
Se |
|
20 |
20 |
20 |
40 |
Ca |
|
11 |
12 |
11 |
23 |
Na |
2.26 Group I
2.28 Group II
2.30 True. Atomic spectra consist of emission of light at frequencies that correspond to energy differences between the ground and the excited atomic states of an atom.
2.34 Two
2.36 Six. A p subshell has 3 orbitals which can each hold 2 electrons.
2.38 Each p orbital has two pear-shaped lobes along an axis. The three p orbitals are perpendicular to each other.
2.56 Atoms want to acquire a valence shell like that of a noble gas. This is eight electrons.
2.58 12C and 13C both contain 6 protons and 6 electrons, but 12C has 6 neutrons and a mass of 12 amu while 13C contains 7 neutrons and thus has a mass of 13 amu. Therefore, their chemical properties are the same, but they have different masses.
2.60 No. The emission spectra of an atom will contain only those wavelengths of light corresponding to transitions between allowed energy levels.
2.66 Yes. Observing the spectral lines when body fluid is incinerated in a flame would be one method of detecting various elements.
2.70 a. This is an excited state of Boron, ground state is 1s2 2s2
b. This is ground state Neon 1s2 2s2 2p6
c. This is excited state Fluorine, ground state is [Ar] 4s2 3d5