Explain why human being is regarded as a complex machine.

Well a human bein is a complex organism with pain and emotion.

There is a very very complex brain that recives and sends sis also faster than the eye can see.

Thats why when you touch a hot surface a lighting fast signal is sent from the hand to the brain and the brain sends a signal back to the hand to tell it what to do and this all happens a faster than a second.

A human is made out of millions, billions, trillions, and quadrillions if cells working together to perform special tasks like eating, walking, and talking.

Humans are the only known species that are able to think as complexly as we do. For example, animals are not able to have thoughts about their thoughts. Animals are not able to ponder the existence of our universe, develop calculus, chemical solutions, etc. There are many other intelligent species- like chimpanzees and octopi. However, both of those species are limited in the type of communication, emotion, and complex thinking skills that they possess compared to human beings.

Explanation:

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.