Question

guided practice problems
answer the following questions about practice problem 10.
use table 4.2 to express the compositions of carbon - 12, fluorine - 19, and beryllium - 9
in shorthand form.
carbon - 12
analyze
step 1. the number of protons in an atom is called its__________number.
the number of protons in an atom of carbon - 12 is__________.
calculate
step 2. the number of protons plus the number of neutrons in an atom is called its
________number. for carbon - 12, this number is________.
step 3. the shorthand notation for carbon - 12 is:
mass number →
c
atomic number →
evaluate
step 4. except for hydrogen - 1, the mass number of an isotope is always greater than its
atomic number. is the mass number reasonable?__________

Explanation:

Step1: Analyze the first part

The number of protons in an atom is called its atomic number. Carbon has an atomic number of 6.

Step2: Analyze the second part

The number of protons plus the number of neutrons in an atom is called its mass number. For carbon - 12, the mass number is 12.

Step3: Determine the shorthand notation

The shorthand notation for an element is \(_{Z}^{A}X\), where \(A\) is the mass number and \(Z\) is the atomic number. For carbon - 12 (\(X = C\)), \(A=12\) and \(Z = 6\).

Step4: Evaluate the mass number

Since \(12>6\), the mass number is reasonable.

Answer:

• Step 1: atomic; 6
• Step 2: mass; 12
• Step 3: \(_{6}^{12}C\) (top box: 12, bottom box: 6)
• Step 4: Yes