answers:
2. valence electrons
3. a bond formed when atoms share one or more pairs of electrons.
4. chemical formula
5. a. calcium - 2
b. carbon - 4
c. sulfur - 6
6. a. electrons
7. the elements that make up water can't be split into a simpler form, but water can. water is a liquid at room temperature, oxygen and hydrogen are gases at room temperature.
8. because it is made of oxygen and hydrogen and one is partially negative and one is partially positive.
explanation: you’re welcome.