Chemical bonding happens when two or more atoms join together to form a molecule. It is a general principle in science that all systems will try to reach their lowest energy level, and chemical bonding will only take place when a molecule can form that has less energy than its uncombined atoms.hemical bonding happens when two or more atoms join together to form a molecule. It is a general principle in science that all systems will try to reach their lowest energy level, and chemical bonding will only take place when a molecule can form that has less energy than its uncombined atoms.
Human beings were able to create tools around 2.5 million years ago-but we first made bows and arrows 64,000 years ago. The invention of the weapons was a huge leap for our ancestors, enabling them to hunt far more effectively.
The use of the bow and arrow for hunting and for war dates back to the Paleolithic period in Africa, Asia, and Europe. It was widely used in ancient Egypt, Mesopotamia, Persia, the Americas, and Europe until the introduction of gunpowder.Arrowheads were first made of burnt wood, then stone or bone, and then metals. recurved bow consists of three partsâtwo flexible limbs extending from opposite ends of a rigid riser. The bow's total length may be 50-70 in (125-175 cm). The riser, which is about 20 in (50 cm) long, provides a comfortable handgrip and a ledge on which the arrow rests prior to release.