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 oldest bows in China and Sub-Saharan Africa date from approximately 3000 years ago. The bow and arrow appeared in North America, roughly 2,500 years ago, it replaced the atlatl (spear thrower) and dart. The bow eventually spread to Mesoamerica by around 100 AD, and to South America by 300 AD.