Using the periodic table entry below, match the phrases with their corresponding values.

1. number of protons

8

2. atomic mass

19

3. number of electrons in the n = 1 shell

2

4. number of electrons in the n = 3 shell

20

5. number of neutrons

39

Atomic mass = 39

number of neutrons = 20

Number of protons = 19

Electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

The number of electron in first shell = 2

number of electrons in n=3 shell = 8

Atomic mass means the summation of total number of protons and neutrons present in an atom.

The given phrases shows that highest number is 39 and it is known that number of neutrons is generally greater than number of protons.

But if there is a large difference in the number of protons and neutrons then it means that the atom is unstable.

Therefore, if number of protons is 19 and number of neutrons is 20 then atomic mass of the atom will be 19 + 20 = 39.

Also, for a neutral atom number of protons equal number of electrons. Hence, electronic distribution for an atom with 19 electrons will be 2, 8, 8, 1.

It means that there are 2 electrons in n = 1, 8 electrons in each n = 2 and n = 3 shell and 1 electron in n = 4 shell.

Thus, we can conclude that the phrases with their corresponding values are matched as follows.

1. number of protons : 19

2. atomic mass : 39

3. number of electrons in the n = 1 shell : 2

4. number of electrons in the n = 3 shell : 8

5. number of neutrons : 20