Question

choose the appropriate atomic number, mass, or property for each description. (p = # of protons; n = # of neutrons)

1. valance electrons in carbon (p = 6, n = 6) (click to select)
2. atomic number of hydrogen (p = 1, n = 1) (click to select)
3. valance electrons in chlorine (p = 17, n = 18) (click to select)
4. atomic mass of carbon (p = 6; n = 6) (click to select)
5. atomic mass of aluminum (p = 13, n = 14) (click to select)
6. atomic number of aluminum (p = 13, n = 14) (click to select)
7. atomic number of zinc (p = 30, n = 35) (click to select)
8. electrons in neon (p = 10, n = 10) (click to select)

Explanation:

Step1: Recall electron - configuration rules for valence electrons

The number of valence electrons can be determined from the group number in the periodic table for main - group elements. Carbon is in group 4A, so it has 4 valence electrons.

Step2: Recall atomic number definition

The atomic number is equal to the number of protons. For hydrogen, with $P = 1$, the atomic number is 1.

Step3: Determine valence electrons of chlorine

Chlorine is in group 7A, so it has 7 valence electrons.

Step4: Calculate atomic mass formula

Atomic mass ($A$) is the sum of the number of protons ($P$) and neutrons ($N$). For carbon with $P = 6$ and $N = 6$, $A=P + N=6 + 6 = 12$.

Step5: Calculate atomic mass of aluminum

For aluminum with $P = 13$ and $N = 14$, $A=P + N=13+14 = 27$.

Step6: Recall atomic number concept

The atomic number of aluminum is equal to the number of protons. Since $P = 13$ for aluminum, the atomic number is 13.

Step7: Recall atomic number concept for zinc

The atomic number of zinc is equal to the number of protons. Since $P = 30$ for zinc, the atomic number is 30.

Step8: Recall electron - proton relationship in neutral atoms

In a neutral atom, the number of electrons is equal to the number of protons. For neon with $P = 10$, the number of electrons is 10.

Answer:

1. 4
2. 1
3. 7
4. 12
5. 27
6. 13
7. 30
8. 10