Why are chemical changes considered unseen?

What part of the ear is names after tools, such as the hammer and the anvil?

An atom that has gained or lost electrons is called an _

The amount of heat required to change liquid water to vapor at its boiling temperature is 2256 kj/kg. the amount of heat required to change liquid mercury to its vapor state at its boiling temperature is 295 kj/kg. one kg of each substance is currently at its boiling point. how will the amount of thermal energy required to change each substance from a liquid to a gas differ?