Question

8.give the symbol and number of electrons in a neutral atom of:
uranium _____________ chlorine _____________
boron ______________ iodine ______________
antimony _____________xenon ______________

9.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 num
your calculations.

barium _____________bismuth _____________
carbon _____________hydrogen _____________
fluorine _____________magnesium _____________
europium _____________mercury _____________

10.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 ________________

11 .if you know only the following information can you always determine wha
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

Step 1: Recall atomic number (protons = electrons in neutral atom)

For Uranium: Atomic number (Z) = 92, so symbol U, electrons = 92.
For Chlorine: Z = 17, symbol Cl, electrons = 17.
For Boron: Z = 5, symbol B, electrons = 5.
For Iodine: Z = 53, symbol I, electrons = 53.
For Antimony: Z = 51, symbol Sb, electrons = 51.
For Xenon: Z = 54, symbol Xe, electrons = 54.

Step 1: Mass number (A) = round(atomic mass), Neutrons (N) = A - Z

• Barium: Z = 56, Atomic mass ≈ 137.33 → A = 137, N = 137 - 56 = 81, symbol Ba.
• Bismuth: Z = 83, Atomic mass ≈ 208.98 → A = 209, N = 209 - 83 = 126, symbol Bi.
• Carbon: Z = 6, Atomic mass ≈ 12.01 → A = 12, N = 12 - 6 = 6, symbol C.
• Hydrogen: Z = 1, Atomic mass ≈ 1.008 → A = 1, N = 1 - 1 = 0, symbol H.
• Fluorine: Z = 9, Atomic mass ≈ 18.998 → A = 19, N = 19 - 9 = 10, symbol F.
• Magnesium: Z = 12, Atomic mass ≈ 24.305 → A = 24, N = 24 - 12 = 12, symbol Mg.
• Europium: Z = 63, Atomic mass ≈ 151.96 → A = 152, N = 152 - 63 = 89, symbol Eu.
• Mercury: Z = 80, Atomic mass ≈ 200.59 → A = 201, N = 201 - 80 = 121, symbol Hg.

Step 1: Element is determined by protons (atomic number Z)

a. Protons = 26 → Z = 26 → Iron (Fe).
b. Protons = 53 → Z = 53 → Iodine (I).
c. Neutral atom: electrons = protons = 2 → Z = 2 → Helium (He).
d. Protons = 20 → Z = 20 → Calcium (Ca).
e. Protons = 82 → Z = 82 → Lead (Pb); charged (electrons = 86 > protons = 82 → anion, but element is Pb).
f. Neutrons = 0, protons = 1 (only H has 0 neutrons) → Hydrogen (H).

Answer:

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

Question 9