Question

9ps
atomic number, mass number, isotopes, and stuff
1 complete the following questions. assume all atoms are neutral.
$_2^4he$
element: ____

protons: ____

neutrons: ____

$_ {26}^{56}fe$
element: ____
atomic #: ____
mass #: ____
$_{13}^{27}al$
element: ____

protons: ____

electrons: ____

$_{20}^{40}ca$
element: ____

protons: ____

neutrons: ____

electrons: ____

$_{10}^{20}ne$
element: ____
atomic #: ____

electrons: ____

atomic mass: ____
$_6^{14}c$
element: ____

protons: ____

electrons: ____

neutrons: ____

$_9^{19}f$
element: ____
atomic #: ____
mass #: ____

electrons: ____

$_1^1h$
element: ____
atomic #: ____

electrons: ____

neutrons: ____

$_1^2h$
element: ____

protons: ____

electrons: ____

neutrons: ____

1. write the symbol for the isotope...

a. with 8 protons and 8 neutrons
b. with 28 protons and 30 neutrons
c. with atomic # 11 and mass # of 23
d. with 92 protons and mass # 238
how many neutrons are in this isotope?

Explanation:

Step1: Recall atomic - related concepts

The atomic number ($Z$) is equal to the number of protons. For a neutral atom, the number of electrons is equal to the number of protons. The mass number ($A$) is the sum of the number of protons and neutrons ($A = p + n$), so the number of neutrons $n=A - p$.

Step2: Analyze $\ce{_2^4He}$

• Element: Helium
• # protons: 2 (from the sub - script)
• # neutrons: $4 - 2=2$ (mass number 4 minus proton number 2)

Step3: Analyze $\ce{_{26}^{56}Fe}$

• Element: Iron
• Atomic # (same as # protons): 26
• Mass #: 56

Step4: Analyze $\ce{_{13}^{27}Al}$

• Element: Aluminum
• # protons: 13
• # electrons: 13 (since it's neutral)

Step5: Analyze $\ce{_{20}^{40}Ca}$

• Element: Calcium
• # protons: 20
• # neutrons: $40 - 20 = 20$
• # electrons: 20

Step6: Analyze $\ce{_{10}^{20}Ne}$

• Element: Neon
• Atomic #: 10
• # electrons: 10
• Atomic mass (same as mass number here): 20

Step7: Analyze $\ce{_{6}^{14}C}$

• Element: Carbon
• # protons: 6
• # electrons: 6
• # neutrons: $14 - 6=8$

Step8: Analyze $\ce{_{9}^{19}F}$

• Element: Fluorine
• Atomic #: 9
• Mass #: 19
• # electrons: 9

Step9: Analyze $\ce{_1^1H}$

• Element: Hydrogen
• Atomic #: 1
• # electrons: 1
• # neutrons: $1 - 1 = 0$

Step10: Analyze $\ce{_1^2H}$

• Element: Hydrogen (isotope called deuterium)
• # protons: 1
• # electrons: 1
• # neutrons: $2 - 1=1$

Step11: Write isotope symbols for part 2

• a. With 8 protons and 8 neutrons, atomic number $Z = 8$ (oxygen), mass number $A=8 + 8=16$. Symbol: $\ce{_8^{16}O}$
• b. With 28 protons and 30 neutrons, atomic number $Z = 28$ (nickel), mass number $A=28+30 = 58$. Symbol: $\ce{_{28}^{58}Ni}$
• c. With atomic # 11 (sodium) and mass # 23, symbol: $\ce{_{11}^{23}Na}$
• d. With 92 protons (uranium) and mass # 238, symbol: $\ce{_{92}^{238}U}$

Answer:

$\ce{_2^4He}$:

• element: Helium
• # protons: 2
• # neutrons: 2

$\ce{_{26}^{56}Fe}$:

• element: Iron
• atomic #: 26
• mass #: 56

$\ce{_{13}^{27}Al}$:

• element: Aluminum
• # protons: 13
• # electrons: 13

$\ce{_{20}^{40}Ca}$:

• element: Calcium
• # protons: 20
• # neutrons: 20
• # electrons: 20

$\ce{_{10}^{20}Ne}$:

• element: Neon
• atomic #: 10
• # electrons: 10
• atomic mass: 20

$\ce{_{6}^{14}C}$:

• element: Carbon
• # protons: 6
• # electrons: 6
• # neutrons: 8

$\ce{_{9}^{19}F}$:

• element: Fluorine
• atomic #: 9
• mass #: 19
• # electrons: 9

$\ce{_1^1H}$:

• element: Hydrogen
• atomic #: 1
• # electrons: 1
• # neutrons: 0

$\ce{_1^2H}$:

• element: Hydrogen
• # protons: 1
• # electrons: 1
• # neutrons: 1

2.

• a. $\ce{_8^{16}O}$
• b. $\ce{_{28}^{58}Ni}$
• c. $\ce{_{11}^{23}Na}$
• d. $\ce{_{92}^{238}U}$