Three groups
gases, metals, metalliods/nonmetals
Six protons, six electrons, and six neutrons. The atom you are looking for is Carbon. The mass number is 12.
Mass number = protons + neutrons
Answer:
In any ecosystem, organisms and populations with similar requirements for food, water, oxygen, or other resources may compete with each other for limited resources, access to which consequently constrains their growth and reproduction. Growth of organisms and population increases are limited by access to resources.