Overview
This lecture explains how to use the periodic table to determine the number of protons, electrons, and neutrons in a bromine atom.
Identifying Atomic Structure Using the Periodic Table
- The atomic number (top number) of bromine (Br) is 35, which equals the number of protons.
- In a neutral atom, the number of protons equals the number of electrons.
- Therefore, a bromine atom has 35 electrons to balance its 35 protons.
Calculating Neutrons in Bromine
- The atomic mass (mass number) of bromine is rounded to 80 for calculation.
- Mass number equals the sum of protons and neutrons.
- Subtracting the atomic number from the mass number gives the number of neutrons: 80 - 35 = 45.
- Therefore, bromine has 45 neutrons.
Key Terms & Definitions
- Atomic Number — Number of protons in the nucleus of an atom.
- Atomic Mass (Mass Number) — Total number of protons and neutrons in an atom's nucleus.
- Neutron — A neutral particle in the nucleus; number calculated by mass number minus atomic number.
- Proton — A positively charged particle in the nucleus.
- Electron — A negatively charged particle surrounding the nucleus.
Action Items / Next Steps
- Practice using the periodic table to find protons, electrons, and neutrons for other elements.
- Complete the assigned homework question related to bromine’s atomic structure.