Behind closed doors with the experts who study the end of the world—and what they know about humanity’s capacity for survival ...

Chlorine is more reactive than the iodine in potassium iodide solution: When a Group 7 element reacts, it gains one electron to form a negative ion with a stable electronic configuration – a full ...

When an object, such as a spring, is stretched, the increased length is called its extension. Key fact Hooke's law: The extension of a spring is directly proportional to the force applied, provided ...