Final answer:
Valence electrons are determined by an element's group number: Oxygen (O) and Sulfur (S) both have 6 valence electrons, Bromine (Br) has 7 valence electrons, and Rubidium (Rb) has 1 valence electron. These electrons play a key role in chemical bonding and the octet rule.
Step-by-step explanation:
The number of valence electrons for each element is based on their position in the periodic table, particularly their group number. Here's a list of the valence electrons for the given elements:
- Oxygen (O) is in group 16 and therefore has 6 valence electrons.
- Sulfur (S) is also in group 16 and has 6 valence electrons.
- Bromine (Br) is a halogen in group 17 and has 7 valence electrons.
- Rubidium (Rb) is an alkali metal in group 1 and has 1 valence electron.
These valence electrons are important in determining how atoms will bond with each other to form compounds, following the octet rule where atoms tend to have eight electrons in their valence shell to achieve stability, similar to noble gases.