Jean Piaget was the one who came up with the <span>four stages of intellectual (or cognitive) development and these are sensorimotor, pre operational, concrete operational and formal operational. The state in which a child has developed object permanence by the end of the sensorimotor stage. Hope this answers your question.</span>
The atomic number is defined by the number of protons in an element. An element is defined by the number of protons the nucleus contains and doesn't have anything to do with how many isotopes the element has. Carbon always has an atomic number of 6 and uranium always has an atomic number of 92. I GOTCHU BROOOO GET THATS A BUDDY
