Question

1. give the symbol and number of electrons in a neutral atom of:

uranium __________ chlorine __________
boron ____________ iodine ___________
antimony. ___________ xenon ___________

1. give the symbol and number of neutrons in one atom of:

(to get “mass number”, you must round the “atomic mass” to the nearest whole number)) show your calculations.

barium ___________ bismuth ___________
carbon ____________ hydrogen ___________
fluorine ___________ magnesium ___________
europium ___________ mercury ___________

1. name the element which has the following numbers of particles:

a.26 electrons,29 neutrons,26 protons _____________

b.53 protons,74 neutrons _____________

c.2 electrons (neutral atoms)_____________

d.20 protons _____________

e.86 electrons,125 neutrons,82 protons (charged atom
_____________

f.0 neutrons _____________

1. if you know only the following information can you always determine what the element is? (yes/no).

a. number of protons ________

b.number of neutrons________

c.number of electrons in a neutral atom________

d.number of electrons________

Explanation:

Question 8

To solve for the symbol and number of electrons in a neutral atom, we use the fact that in a neutral atom, the number of electrons equals the number of protons (atomic number).

• Uranium: Symbol is $U$, atomic number is 92, so electrons = 92.
• Chlorine: Symbol is $Cl$, atomic number is 17, so electrons = 17.
• Boron: Symbol is $B$, atomic number is 5, so electrons = 5.
• Iodine: Symbol is $I$, atomic number is 53, so electrons = 53.
• Antimony: Symbol is $Sb$, atomic number is 51, so electrons = 51.
• Xenon: Symbol is $Xe$, atomic number is 54, so electrons = 54.

Question 9

To find neutrons, use the formula: $\text{Neutrons} = \text{Mass Number} - \text{Atomic Number}$. Mass number is rounded atomic mass.

• Barium: Symbol $Ba$, atomic number 56, atomic mass ~137.33 (round to 137). Neutrons = $137 - 56 = 81$.
• Bismuth: Symbol $Bi$, atomic number 83, atomic mass ~208.98 (round to 209). Neutrons = $209 - 83 = 126$.
• Carbon: Symbol $C$, atomic number 6, atomic mass ~12.01 (round to 12). Neutrons = $12 - 6 = 6$.
• Hydrogen: Symbol $H$, atomic number 1, atomic mass ~1.01 (round to 1). Neutrons = $1 - 1 = 0$.
• Fluorine: Symbol $F$, atomic number 9, atomic mass ~18.998 (round to 19). Neutrons = $19 - 9 = 10$.
• Magnesium: Symbol $Mg$, atomic number 12, atomic mass ~24.305 (round to 24). Neutrons = $24 - 12 = 12$.
• Europium: Symbol $Eu$, atomic number 63, atomic mass ~151.96 (round to 152). Neutrons = $152 - 63 = 89$.
• Mercury: Symbol $Hg$, atomic number 80, atomic mass ~200.59 (round to 201). Neutrons = $201 - 80 = 121$.

Question 10

The element is determined by the number of protons (atomic number).

• a. 26 protons: Element is Iron ($Fe$).
• b. 53 protons: Element is Iodine ($I$).
• c. 2 electrons (neutral): Protons = 2, element is Helium ($He$).
• d. 20 protons: Element is Calcium ($Ca$).
• e. 82 protons: Element is Lead ($Pb$) (charged, but protons determine element).
• f. 0 neutrons, 1 proton (implied, as 0 neutrons + 1 proton = mass 1): Element is Hydrogen ($H$).

Question 11

• a. Number of protons: Yes (protons = atomic number, unique to each element).
• b. Number of neutrons: No (isotopes have same protons, different neutrons).
• c. Electrons in neutral atom: Yes (electrons = protons = atomic number).
• d. Number of electrons: No (ions have different electrons, same element can have different charges).

Final Answers (Key Points)

Q8

• Uranium: $U$, 92 electrons
• Chlorine: $Cl$, 17 electrons
• Boron: $B$, 5 electrons
• Iodine: $I$, 53 electrons
• Antimony: $Sb$, 51 electrons
• Xenon: $Xe$, 54 electrons

Q9

• Barium: $Ba$, 81 neutrons
• Bismuth: $Bi$, 126 neutrons
• Carbon: $C$, 6 neutrons
• Hydrogen: $H$, 0 neutrons
• Fluorine: $F$, 10 neutrons
• Magnesium: $Mg$, 12 neutrons
• Europium: $Eu$, 89 neutrons
• Mercury: $Hg$, 121 neutrons

Q10

• a. Iron ($Fe$)
• b. Iodine ($I$)
• c. Helium ($He$)
• d. Calcium ($Ca$)
• e. Lead ($Pb$)
• f. Hydrogen ($H$)

Q11

• a. Yes
• b. No
• c. Yes
• d. No

Answer:

Question 8

To solve for the symbol and number of electrons in a neutral atom, we use the fact that in a neutral atom, the number of electrons equals the number of protons (atomic number).

• Uranium: Symbol is $U$, atomic number is 92, so electrons = 92.
• Chlorine: Symbol is $Cl$, atomic number is 17, so electrons = 17.
• Boron: Symbol is $B$, atomic number is 5, so electrons = 5.
• Iodine: Symbol is $I$, atomic number is 53, so electrons = 53.
• Antimony: Symbol is $Sb$, atomic number is 51, so electrons = 51.
• Xenon: Symbol is $Xe$, atomic number is 54, so electrons = 54.

Question 9

To find neutrons, use the formula: $\text{Neutrons} = \text{Mass Number} - \text{Atomic Number}$. Mass number is rounded atomic mass.

• Barium: Symbol $Ba$, atomic number 56, atomic mass ~137.33 (round to 137). Neutrons = $137 - 56 = 81$.
• Bismuth: Symbol $Bi$, atomic number 83, atomic mass ~208.98 (round to 209). Neutrons = $209 - 83 = 126$.
• Carbon: Symbol $C$, atomic number 6, atomic mass ~12.01 (round to 12). Neutrons = $12 - 6 = 6$.
• Hydrogen: Symbol $H$, atomic number 1, atomic mass ~1.01 (round to 1). Neutrons = $1 - 1 = 0$.
• Fluorine: Symbol $F$, atomic number 9, atomic mass ~18.998 (round to 19). Neutrons = $19 - 9 = 10$.
• Magnesium: Symbol $Mg$, atomic number 12, atomic mass ~24.305 (round to 24). Neutrons = $24 - 12 = 12$.
• Europium: Symbol $Eu$, atomic number 63, atomic mass ~151.96 (round to 152). Neutrons = $152 - 63 = 89$.
• Mercury: Symbol $Hg$, atomic number 80, atomic mass ~200.59 (round to 201). Neutrons = $201 - 80 = 121$.

Question 10

The element is determined by the number of protons (atomic number).

• a. 26 protons: Element is Iron ($Fe$).
• b. 53 protons: Element is Iodine ($I$).
• c. 2 electrons (neutral): Protons = 2, element is Helium ($He$).
• d. 20 protons: Element is Calcium ($Ca$).
• e. 82 protons: Element is Lead ($Pb$) (charged, but protons determine element).
• f. 0 neutrons, 1 proton (implied, as 0 neutrons + 1 proton = mass 1): Element is Hydrogen ($H$).

Question 11

• a. Number of protons: Yes (protons = atomic number, unique to each element).
• b. Number of neutrons: No (isotopes have same protons, different neutrons).
• c. Electrons in neutral atom: Yes (electrons = protons = atomic number).
• d. Number of electrons: No (ions have different electrons, same element can have different charges).

Final Answers (Key Points)

Q8

• Uranium: $U$, 92 electrons
• Chlorine: $Cl$, 17 electrons
• Boron: $B$, 5 electrons
• Iodine: $I$, 53 electrons
• Antimony: $Sb$, 51 electrons
• Xenon: $Xe$, 54 electrons

Q9

• Barium: $Ba$, 81 neutrons
• Bismuth: $Bi$, 126 neutrons
• Carbon: $C$, 6 neutrons
• Hydrogen: $H$, 0 neutrons
• Fluorine: $F$, 10 neutrons
• Magnesium: $Mg$, 12 neutrons
• Europium: $Eu$, 89 neutrons
• Mercury: $Hg$, 121 neutrons

Q10

• a. Iron ($Fe$)
• b. Iodine ($I$)
• c. Helium ($He$)
• d. Calcium ($Ca$)
• e. Lead ($Pb$)
• f. Hydrogen ($H$)

Q11

• a. Yes
• b. No
• c. Yes
• d. No