Bromine has an atomic number of 35 and a mass number of 80. Match the number of protons, neutrons, and electrons in a bromide ion with a -1 charge. (Remember that an ion has an unequal number of protons and electrons. Positive ions have lost electrons. Negative ions have gained electrons.)

Question

80 -1
35 Br

How many protons does the Br-1 ion have? (The atomic number tells you the number of protons)

How many electrons does the Br-1 ion have? (Remember: if the ion is negative, it has gained electrons. To find the number of electrons, take the atomic number and add the charge of the ion.)

How many neutrons does the Br-1 ion have? (Remember: mass number - atomic number = # neutrons)

Choices: 16, 34, 36, 115, 45, 35

choose the correct answers

Answer 1

To determine the number of protons, neutrons, and electrons in a bromide ion (Br⁻) with an atomic number of 35 and a mass number of 80, we can break it down as follows:

1. Protons:

   • The atomic number (35) indicates the number of protons.
   • Protons in Br⁻ = 35

2. Electrons:

   • The bromide ion has a -1 charge, which means it has gained one additional electron.
   • Therefore, the number of electrons is the atomic number plus the charge:
   • Electrons in Br⁻ = 35 (atomic number) + 1 (charge) = 36

3. Neutrons:

   • To find the number of neutrons, we subtract the atomic number from the mass number:
   • Neutrons = Mass number - Atomic number = 80 - 35 = 45

In summary:

• Number of protons in Br⁻: 35
• Number of electrons in Br⁻: 36
• Number of neutrons in Br⁻: 45

The correct answers are:

• Protons: 35
• Electrons: 36
• Neutrons: 45